CA2246724C - Method and device for directional emission and reception of electromagnetic waves - Google Patents
Method and device for directional emission and reception of electromagnetic waves Download PDFInfo
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- CA2246724C CA2246724C CA002246724A CA2246724A CA2246724C CA 2246724 C CA2246724 C CA 2246724C CA 002246724 A CA002246724 A CA 002246724A CA 2246724 A CA2246724 A CA 2246724A CA 2246724 C CA2246724 C CA 2246724C
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
- H01Q13/02—Waveguide horns
- H01Q13/04—Biconical horns
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
- H01Q25/04—Multimode antennas
Abstract
The invention relates to a high-mode operating resonator, e.g. a coaxial wave-guide, wherein various oscillation modes of an electromagnetic field are coupled in and superimposed on each other. The mixed mode thus arising from the excitation field is used to excite an antenna, preferably a biconical antenna. The azimuthal emission characteristic of the electromagnetic wave emitted by the antenna has the same dependency as the azimuthal field distribution in the resonator. The emission characteristic has in particular, in the case of an azimuthal and anisotropic excitation field, privileged directions in the azimuthal emission. A change of direction of the maximum emission of the electromagnetic wave occurs through an additional change of the phase or amplitude relationships between the coupled electromagnetic field modes.
Description
METHOD AND DEVICE FOR DIRECTIONAL EMISSION
AND RECEPTION OF ELECTROMAGNETIC WAVE
Field of the Invention The invention relates to a method for the directionally selective transmission of electromagnetic waves, in particular for application in radio communications, as. well as to a device for carrying out said method.
Related Art Due to the propagation-properties of electromagnetic waves in the atmosphere, only a frequency band of between 30 Mfiz and 300D MHz is available for terrestrial radio communications covering large service areas. The growing importance of radio communications leads to the necessity of exploiting-~tfiis.
limited available range as efficiently as possible. Special so-called multiplex methods are employed in connection with existing radio communication systems for enhanced exploitation of the time and frequency ranges, as well as in the coding sector. Sawever,:only limited expansion of the capacity is, possible-in said ranges. Directionally selective transmission of information may offer as alternative.
AUG-14-1998 13~04 COLLARD & ROE - 516 365 9805 P.03i22 antennas with a directional effect are known, which, because of their special geometry, have an azimuthally anisotropic radiation characteristic (cf, e.g., LUEGER:
Zexikon der Technik, Elektrotechnik and Kerntechnik-Grundlagen [Lexicon of Technology; Fundamentals of Electrical and .Nuclear Engineeringl, Reinbek near Hamburg; ;9721.: In the frequency range specified above, predominantly so-called aperture antennas or group arrangements of a plurality of individual antennas Y
are used, which are controlled by means of an extensive supply network. If the main direction of transmission of a group of antennas~is to be variable, electronically controllable setting elements have to be employed in the supply network for the amplitude and/or phase. However, the use of such setting elements is costly and connected with capacity losses. For this reason, directionally selective transmission of electro-magnetic waves has hardly been used heretofore for capacity expansion purposes in the. sector of radio communications.
An approach for generating directional beams deviating from the above is specified in US.4,947,178. The object of this document is an antenna arrangement 'in which several circular disk-shaped individual antennas are arranged coaxially but equidistantly spaced from each other vertically, and excited independently of each other by separate feed lines. The individual antennas have different diameters, which are selected in such a way that a predetermined electromagnetic oscillation mode can be -2~
i AUG-14-1998 13~04 COLLARD & ROE ~ 516 365 9805 f resonantly coupled to each individual antenna. The fields emitted by the excited individual antennas superimpose one another, forming an overall field of radiation, the geometry of which corresponds with the geometry of a linear superposition of the coupled-in oscillation modes of the individual antennas.
However, the desired superposition of predetermined oscillation modes is only incomplete with said object because interference fields originate from an excited individual antenna that noticeably impair the development of the mode in adjacent individual antennas. Furthermore, as each of the individual antennas has to be provided with its own feed line as well as with amplitude and phase shifters, the structural expenditure..
of said arrangement is very high, and the total number of individual antennas which can be assembled for the antenna arrangement is at the same time hmited,'the consequence of which is that only a low number of different modes of oscillation can be combined with each other and the achievable directional effect is therefore quite unsatisfactory overall.
Therefore, the problem of the present invention is to create a possibility for the directionally selective transmitting and/or receiving of electromagnetic waves, in connection with which the directional characteristic can be selected and influenced in a simplified manner versus the state of the art.
Summary of the Invent~.on As opposed to-the directional antennas according to the state of the art, where the directional selectivity of the transmission is achieved through a special. geometry of the antenna or antexiz~.a arrangement, a directional selection is created in connection w~.th the invention already in the excitation ffield in the feed line serving far the excitation of the antenna. This is accomplished by superposing electro-magnetic oscillation modes, which are generated in a resonator as its natural modes, said resonator being operatable in excess mode. Each electromagnetic oscillation mode effects a characteristic local dependence of the electric or magnetic field vectors. By the linear superposition of suitable oscillation modes it is possible to achieve almost any desired dependence upon the az~;matt~.al angle of the resulting field.
If such a ffield is used for exciting an antenna, the emission from the antenna also can take place with only one aaimuthal directional characteristic conforming to the directional dependence of the exciting field. Such a method permits in connection With directional transmission the use of antennas .
without own directionally selective radiation characteristic.
AND RECEPTION OF ELECTROMAGNETIC WAVE
Field of the Invention The invention relates to a method for the directionally selective transmission of electromagnetic waves, in particular for application in radio communications, as. well as to a device for carrying out said method.
Related Art Due to the propagation-properties of electromagnetic waves in the atmosphere, only a frequency band of between 30 Mfiz and 300D MHz is available for terrestrial radio communications covering large service areas. The growing importance of radio communications leads to the necessity of exploiting-~tfiis.
limited available range as efficiently as possible. Special so-called multiplex methods are employed in connection with existing radio communication systems for enhanced exploitation of the time and frequency ranges, as well as in the coding sector. Sawever,:only limited expansion of the capacity is, possible-in said ranges. Directionally selective transmission of information may offer as alternative.
AUG-14-1998 13~04 COLLARD & ROE - 516 365 9805 P.03i22 antennas with a directional effect are known, which, because of their special geometry, have an azimuthally anisotropic radiation characteristic (cf, e.g., LUEGER:
Zexikon der Technik, Elektrotechnik and Kerntechnik-Grundlagen [Lexicon of Technology; Fundamentals of Electrical and .Nuclear Engineeringl, Reinbek near Hamburg; ;9721.: In the frequency range specified above, predominantly so-called aperture antennas or group arrangements of a plurality of individual antennas Y
are used, which are controlled by means of an extensive supply network. If the main direction of transmission of a group of antennas~is to be variable, electronically controllable setting elements have to be employed in the supply network for the amplitude and/or phase. However, the use of such setting elements is costly and connected with capacity losses. For this reason, directionally selective transmission of electro-magnetic waves has hardly been used heretofore for capacity expansion purposes in the. sector of radio communications.
An approach for generating directional beams deviating from the above is specified in US.4,947,178. The object of this document is an antenna arrangement 'in which several circular disk-shaped individual antennas are arranged coaxially but equidistantly spaced from each other vertically, and excited independently of each other by separate feed lines. The individual antennas have different diameters, which are selected in such a way that a predetermined electromagnetic oscillation mode can be -2~
i AUG-14-1998 13~04 COLLARD & ROE ~ 516 365 9805 f resonantly coupled to each individual antenna. The fields emitted by the excited individual antennas superimpose one another, forming an overall field of radiation, the geometry of which corresponds with the geometry of a linear superposition of the coupled-in oscillation modes of the individual antennas.
However, the desired superposition of predetermined oscillation modes is only incomplete with said object because interference fields originate from an excited individual antenna that noticeably impair the development of the mode in adjacent individual antennas. Furthermore, as each of the individual antennas has to be provided with its own feed line as well as with amplitude and phase shifters, the structural expenditure..
of said arrangement is very high, and the total number of individual antennas which can be assembled for the antenna arrangement is at the same time hmited,'the consequence of which is that only a low number of different modes of oscillation can be combined with each other and the achievable directional effect is therefore quite unsatisfactory overall.
Therefore, the problem of the present invention is to create a possibility for the directionally selective transmitting and/or receiving of electromagnetic waves, in connection with which the directional characteristic can be selected and influenced in a simplified manner versus the state of the art.
Summary of the Invent~.on As opposed to-the directional antennas according to the state of the art, where the directional selectivity of the transmission is achieved through a special. geometry of the antenna or antexiz~.a arrangement, a directional selection is created in connection w~.th the invention already in the excitation ffield in the feed line serving far the excitation of the antenna. This is accomplished by superposing electro-magnetic oscillation modes, which are generated in a resonator as its natural modes, said resonator being operatable in excess mode. Each electromagnetic oscillation mode effects a characteristic local dependence of the electric or magnetic field vectors. By the linear superposition of suitable oscillation modes it is possible to achieve almost any desired dependence upon the az~;matt~.al angle of the resulting field.
If such a ffield is used for exciting an antenna, the emission from the antenna also can take place with only one aaimuthal directional characteristic conforming to the directional dependence of the exciting field. Such a method permits in connection With directional transmission the use of antennas .
without own directionally selective radiation characteristic.
Therefore, as opposed to the object of US 4,947,178, no defined antenna geometry is required for promoting the development of individual electromagnetic field modes..The geometry of the exiter;field and thus also the radiation characteristic of the emitted electromagnetic field are variable in a very comprehensive and rapid manner by a change effected in the control of the resonator. This creates a highly efficient possibility for directionally selective transmission.
In order to obtain a predetermined directional characteristic, the individual oscillation modes are coupled into the resonator, with a preset amplitude and/or phase ratio. The directional characteristic is variable also in a predetermined manner by changing the length of the resonator.
The direction of radiation can be advantageously changed also by coupling the oscillation modes into the resonator from a predetermined but variable azimuthal direction.
In addition to the transverse electromagnetic basic mode, the so-called TEM--mode, one or several higher modes of the TES,-type are usefully generated in the resonator and super-posed on.the basic mode. In particular, by superposing the TEM-mode with the T~11-mode, an exciting field is created which effects the development of a unilateral radiation characteristic on the antenna. When a higher oscillation mode is superposed on the TEM basic mode with a predetermined amplitude and phase ratio, an anisotropic directional characteristic with a predetermined main direction of radiation of the emitted electromagnetic wave is effected according to the method of the invention. By changing the phase ratio between the higher mode of oseillat3on and the TEM basic mode in a targeted way, a change takes place in the preferred direction of emission that is adapted to the given requirements.
According to another~advantageous development of the invention, a directional characteristic is generated on the antenna which has at least two different main directions of radiation. Thus a so-called "point-to-multipoint" application is possible; i.e., communication of the antenna with a plurality of other transmitting and/or receiving antennas.
The method of the invention differs from the method according to claim 1 in that the antenna is used as a-receiving antenna, whereby the main direction of radiation of a aransmitting~ 'antenna' .. . . . i.~:
communicating with the receiving antenna is determined at regular intervals ana the directional: characteristic of the receiving antenna is adjusted according to the~direction of maximum receiving power. The variation of the main direction of radiation in the detection of~the direction of maximum receiving power and in the new adjustment of the main direction of radiation takes place in an entirely simple manner by accordingly changing the amplitude and/or the phase ratio and/or the direction of azimuthal coupling of the oscillation modes into the resonator actively connected to the receiving antenna. Thus the main direction of radiation is adjustable in each case by electronic weasures and consequently such adjustments~can be carried out rapidly. The method according to the invention is thus suitable especially for application in mobile radio communication installations.
In said device, a resonator is provided with at least one coupling connection far coupling-in an electromagnetic field.
The resoriatox has to be operatable in this connection in excess mode, i.e., so that also higher electromagnetic:
oscillation modes can be generated in addition to the TEM-mode.
With suitable excitation, a electric field consisting.of a mix of modes develops in the resonator, and said field is used for exciting an antenna: The electromagnetic wave.: emitted from the antenna has a directional characteristic cowforming to RUG-14-1998 13:05 COLLRRD & ROE . 516 365 9805 P.09 the mix of modes generated in the resonator.
According to an advantageous further development, a single-conical or a biconical antenna serves as the aerial. Such antennas are known, for example from US 4,851,859, and are characterized by a transmitting and receiving capability that is azimuthally uniform over 360 degrees. Such antennas have been used heretofore for vmnidirectional transmissions. By exciting such an antenna with a directionally selective field of excitation, the transmission, too, takes place with a corresponding directionally selective radiation characteristic.
The application of such an antenna is advantageous primarily for the reason that it permits transmission in almost any desired azimuthal direction with dependence only upon the geometry of the exciting field - which is variable by simple electronic measures ~ without having to change the antenna arrangement in any way. The two halves of the single-conical or biconical antenna also may have different radial diameters, or the inner angles of the two conical haves may be different.
According to another advantageous further development, the resonator in which the electromagnetic oscillation modes are generated can be designed in such a way that it can be tuned by changing its length. The ratio at which the individual oscillation modes develop in the resonator relative to each other _g_ faUG-14-1998 13 = 06 COLLfaRD & ROE - 516 3659805 f . 10122 is variable in this way,.
A particularly simple resonator, which is advantageous especially when cooperating with a single conical or biconial antenna, is make available by a coaxial wave conductor_cahich can be operated in excess mode far generating high electro-magnetic oscillation modes. Furthermore, the inner and outer conductors. of a coaxial wave conductor can be connected without any problem to the two cones of a biconical antenna.
For developing well-defined electromagnetic oscillation modes it is necessary that the coaxial wave conductor has a termination at its end opposing~.ithe connection to the antenna.
Said termination may either consist df a short circuit, for example in the form of a metallic plate electrically connecting both conductors, or such termination is produced by a completely reflection-free arrangement.
ladvantageously, the electromagnetic field is coupled in via at least one coupling connection, which is arranged radially on the ..coaxial wave conduc.tor-on the outside. Reliable coupling of the electromagnetic modes into the resonator is achieved in this way. It is par-ricularly advantageous if the arrangement comprises a plurality of coupling connections, which are arranged in the circumferential di_reation of the coaxial wave conductor _g~
with the same angular spacings. In such an arrangement, the radiation.characteristics each having a different main direction of radiation can be obtained in a simple manner without changing the arrangement of the resonator by addressing different coupling connections depending on the desired direction of emission.
Alternatively to the lateral coupling of the electromagnetic 'field into the resonator coupling takes place by means of a ' coupling connection arranged at the end of the resonator opposing the connection to the antenna. Axial coupling-in is effected in this way.
Coaxial sleeves are suitable as reliable and low-radiation coupling connections.
\~.The electromagnetic field is coupled in via capacitive~and/or inductive coupling elemenfs. Coupling pins or dead-end feeders can be considered in this connection as capaeitive coupling elements, and. coupling loops or coils as inductive coupling .elements. It is particularly advantageous.
if such coupling elements are etched as conducting paths on a conductor board or applied in some other~~aay, whereby the ,10-r pc board is arranged in the resonator in a suitable way.
As.an alternative or to complete the coupling of the electromagnetic wave into the resonator by means of capacitive and/or inductive coupling elements, coupling of the electro-magnetic field takes place by means of one or a plurality of~hollow conductors, which are connected to the resonator on coupling slits and/or coupling holes.
The, coupling connections provided for coupling the electro-magnetic wave into the resonator are usefully connected to a supply network, byWeans of which the amplitudes and/or phases of~the coupled-in oscillation modes can be controlled as well.
This is particularly advantageous because the field distribution of the mixed mode resulting from the superposition of the oscillation modes, and thus also the directional characteristic of the electromagnetic wave emitted by the antenna due to excitation by a field of said mixed mode are dependent with particular sensitivity upon the amplitude and phase ratio of~
the basic oscillation. modes. A great variation width of adjustable directional characteristics is thus available owing to the separate controllability of the amplitudes and~phases.of the tuning modes coupled in.
According to one embodiment of the invention, a single-conical and/or biconical antenna AUG-14-1998 13~06 COLLARD &, ROE - 516 365 9805 P.13i22 is connected to a coaxial wave conductor, which has coupling connections for coupling in electromagnetic oscillation modes both radially on the outside and at its end disposed opposite the connection to the antenna. The coupling connections are connected to a supply network, by means of which the oscillation modes coupled in each can be varied in their amplitudes and/or phases independently of each other. In this connection, a coupling connection arranged opposite the antenna connection preferably serves for coupling in a TEM basic mode, and the other coupling connections serve fox coupling in higher, azimuthally anisotropic oscillation modes. The superposition of the azimuthally anisotropic oscillation modes leads to a directional characteristic of the emitted electromagnetic field that.!.has.one or a plurality of well-defined main directions of radiation_ The main direction of radiation is variably adjustable particularly by changing the phase relation between the azimuthally anisotropic oscillation modes and the TEM basic mode.
The arrangement consisting of the antEnna and the resonator is suitable not only for transmitting but also for receiving electromagnetic waves.
In an advantageous further development, the resonator and the antenna are actively connected to a control electronics, by means of which it is possible to determine a direction of AUG-14-1998 13~0 COLLARD & ROE - 516 365 9805 P.14i22 maximum azimuthal receiving capacity and to ahen adjust the main direction of radiation of the directional characteristic of the maximum receiving capacity accordingly by suitably varying the amplitude and/or the phase ratios and/or the direction of the azimuthal coupling of the oscillation modes.
The direction of maximum receiving capacity can be determined in this connection, for example in such a way that the main direction of radiation of the directional characteristic of the antenna is varied at predetermined time intervals and the outputs received from different azimuthal directions are compared. Owing to the fact that the main direction of radiation can be adjusted by only electronic measures it is possible to newly adjust the main direction of radiation again in a very rapid way, which is advantageous especially in applications in mobile or partly mobile radio communication installations.
According to another advantageous further~::de~~lopment, the control electronics - by means of which the direction of maximum azimuthal receiving capacity is determined - is actively connected to an indicator device, by means of which the azimuthal directional dependence of the receiving capacity is representable by sound or visually. Such a device is particularly suitable for radiolocation.
RUG-14-1998 13~07 COLLRRD & ROE 516 365 9805 P.15i22 The device as defined by the invention is suitable in a particularly advantageous manner as a relay station in a radio communications network. By suitably adjustir_g different main directions of radiation of the directional characteristic it is possible to simultaneously receive signals of a , transmitter as well as to transmit signals to a receiver other than the transmitter. The transmitter and the receiver do not have to be stationary at all in this connection; the rapid Y
electronic adjustability of the principal direction of radiation of the relay station rather permits also the application of the device as defined by the invention in a radio communications network consisting of mobile units_ According to yet another further development, the device as defined by the invention is used in a diversity system for receiving particularly weak signals or signals strongly interfered with. Zn this connection., the diversity consists of a separation between two antennas in terms of space, on the one hand, and of an individually variable directional characteristic of such two antennas, on the other. The correlation of the two receive signals is dependent upon the local separation, on the one hand, and additionally also on the different directional characteristic. The receiving capacity of the arrangement is increased overall by suitably combining the receive signals of both antennas electronically.
~14-.
The solution of the problem as defined by the invention may be also implemented as a radio communication system.
The radio communication system consists of at least two transmitting and receiving units, which each have a resonator provided with at least one coupling connection for coupling in an electromagnetic field, such resonator being actively connected to an antenna. When used as intended, the antenna emits electromagnetic waves with a directional characteristic corresponding with the field dependence of the electromagnetic oscillation modes linearly superposed in the resonator, and at the same time has a predetermined directional characteristic.
A control electronics aligns the main directions of radiation - of a transmitting and receiving unit with the main direction of radiation of transmitting and receiving units each being in radio contact with transmitting and receiving unit.
According to an advantageous further development,, the radio communication system has at least three transmitting-and receiving units, of~which at least one unit is applicable at the same time as a relay point..Due to the rapid electronic.
adjustability.of the main directions,of radiation, the radio communication system is suitable to a particularly high degree for application in radio-communications between mobile subscribers between each other, or between stationary subscribers on the one side and mobile subsc=fibers on the other. The relay a station, for example, may be arranged in a vehicle or on board of a helicopter.
In a particularly advantageous application, the-radi.o communication system is used in a mobile radio communication network, for example in a mobile telephone system. The special advantage of the radio communication system as defined by the invention lies zn.that due to the efficient spatial bunching by means of the electronic adjustment of the main directions of radiation of the participating transmitting and receiving units, the required transmitting power is reduced and the safety against listening-in is enhanced.
Brief Description of the Drawings The invention is explained in greater detail in the following with the help of -the attached .drawing, in which the following is shown schematically:
FIG. 1 shows a biconical antenna connected to a coaxial wave conductor.
FTG. .2 is a longitudinal center section.through the arrangement according to FIG. 1.
FIG. 3 is a sketch illustrating the principle of the method as defined by the invention with the help of field lines and directional characteristics.
... CA 02246724 2004-02-16 FIG. 4 shows a biconical antenna. with a connected coaxial wave conductor in another embodiment.
FIG. S is a sketch illustrating the principle of determination o~ a direction of maximum receiving power in radio communications between two transmitting and receiving units.
FZG. 6 is a sketch illustrating the principle of radio communication between two transmitting and receiving units with interconnection of a relay station.
FIG. 7 is a sketch~illust'rating the principle of radio communication between a~transmitting unit and a plurality o~
r.epe~ving units; and FIG. 8 is a sketch of,the principhe for explaining how the devices as defined by the invention are applied in a local/
anghe diversity system.
Detailed Description of the Preferred Embodiments ~In arrangement 1 shown in'FZGS. 1 and 2, a biconical antenna 2 is mounted on a coaxial wave conductor 3. The two halves 4, 5 of biconical antenna. 2 are. arranged rad.$ally symmetrically relative to each other and with respwet to coaxial wave conductor 3, opposing one another,with their conical AUG-14-1998 13=08 COLLHRD & ROE - 516 365 9805 P.19i22 widenings, and are connected to conical wave conductor 3 in the manner described in the following.
The lower half 5 of biconical antenna 2, said half being disposed directly adjacent to conical wave conductor 3, has the approximate shape of a circular truncated cone, the height of which is selected in such a way that its smallest radius approximately corresponds with the radius of outer conductor 7 of coaxial wave conductor 3. The area of lower half 5 of bioonical antenna 2 is bent .inwardly at the end with the smallest radial expanse and changes into a cylinder-shaped inner section 8, the radius of which corresponds with the one of the outer conductor 7, said inner section being electrically connected to the latter.
Upper half 4 of coaxial wave conductor 3 ,of .Iiiconical~
antenna 2,..~said lia3:f being farther :reriloved;:from coaxial wave conductor 3, changes into the tubular inner conductor 6 of coaxial wave conductor 3 in the manner of a ~unnel_ At the end of coaxial wave conductor 3 opposing biconical antenna 2, outer conductor 7 feeds into a electrically conductive, circular termination plate 9, which is electrically connected also to inner conductor 6.
The short circuyt existing in this way between inner conductor 6 and outer conductor 7 permits the development of preset oscillation modes in coaxial wave conductor 3. In this .. -18-AUG-14-1998 13-08 COLLRRD & ROE 516 365 9805 P.20i22 arrangement, the electrical field vectors oscillating zn the coaxial wave conductor between inner conductor 6 and outer conductor 7 in the radial direction are transformed by the conical widenings of the two antenna halves 4, 5 into an.oscillation mode axis-parallel with conical wave conductor 3 without losing any azimuthal field dependence that may be present. The electromagnetic wave emitted by biconical antenna 2 thus°exhibits an azimuthal dependence which corresponds with the azimuthal directional dependence of the electric field in coaxial wave conductor 3.
For coupling electromagnetic fields into coaxial wave conductor 3, a total of eight connection sleeves 10 are arranged radialiy on outer conductor 7 on the outer side in the present exemplified embodimenty said connection sleeves being of the same type among each other and each having the same angular spacing. Between connection sleeves 10, a conductor board 11 - which itself is not conductive - extends radially through the entire coaxial wave conductor 3, with capacitive and/or.inductove coupling elements - not shown in the drawing - in the form of etched-in conductor paths being arranged on said conductor board.
An electromagnetic wave is induced in coaxial wave conductor 3 by means of the coupling elements arranged on AUG-14-1998 13~08 COLLARD & ROE . 516 365 9805 P.~li conductor board 11. Coaxial wave conductor 3 is operated in this connection in excess mode. Further, higher oscillation conditions are generated in addition to the TEr2 basic mode.
The different oscillation modes of coaxial wave conductor 3 lead to corresponding oscillation modes in biconical antenna 2, which is electrically connected to said modes, and lead to corresponding electromagnetic waves in said antenna for emission.
It is explained in the following with the help of FIG. 3 on the example of superposition of two electromagnetic oscillation modes, the TEM basic mode and the TE11-mode, how a directionally selective transmission is effected by the antenna in an arrangement according to FTG. 1 or FIG. 2_ The electric field distribution in coaxial wave conductor 3 is radially symmetric in the case of the TEM basic mode.
Azimuthal radiation characteristic 20, which corresponds with said form o~ oscillation, shows an isotropic curve accordingly_ On the other hand, excitation of a TE1.1-mode leads to an anisotropic azimuthal dependence 21 in coaxial wave conductor 3 as well as to an anisotropic azimuthal radiation characteristic 22, which is characterized by an axis of maximum radial electric field distribution in coaxial wave conductor 3 and by a main direction of radiation -20' RUG-14-1998 13~28 COLLRRD & ROE . 516 ~b5 ~bd5 r.bG~G4 in radiation characteristic 22, in the present example along lines 90° - 270°. The electric field vectors oscillate in the coaxial wave conductor along said axis on both sides of inner conductor 6 in phase opposition.
With linear superposition of a TEM-mode with a TElI-mode, the component o~ the electric field of the TEll-mode oscillating in-phase with the TEM-mode is therefore amplified in coaxial wave conductor 3, whereas the inphase-opposed component is weakened, as shown by ~ield distribution 23 of the TEM-TEll-mixed mode. Radiation characteristic 24 corresponding with said mixed mode shows a single preferred direction of maximum emission, in the example in the 270°
direction.
When arrangement 1 is applied as intended, emission is achieved in this way in a predetermined direction. By addressing one of connections 10 in a controlled manner it is possible in this connection to vary the direction in azimuthal angles corresponding with the angular spacings of the individual connections Z0, whereby each addressing of one of connections leads to a same type of supezposition of the oscillation modes as described above, however, in each case with anatherw preferred direction_ In the case of the eight connections of arrangement l, eight different preferred directions can b~
_~l_ RUG-14-1998 13=28 COLLRRD & ROE 516 365 9805 -F.03i24 achieved in this way in the transmission of the electro-magnetic wave on antenna 2.
Arrangement 30 shown in FIG. 4 has a structure modified as compared to arrangement 1. Biconical antenna 2 and the coaxial wave conductor 3 are structured in the same way as in arrangement 1. l3owever, instead of the eight lateral connections 10, arrangement 30 has only two radial connections 31, 32 arranged at an angle of 90° relative to each other, said conr~ections being arranged radially on outer conductor 7 on the outer side, as well as an axial connection 33 at the end of coaxial wave conductor 3 opposing the antenna. Connections 31, 32, 33 are connected to a supply network 35, which supplies the electria.energy reguired for coupling in predetermined electromagnetic oscillation modes.
Setting elements 36, 37 for controlling the amplitudes of the electromagnetic field modes coupled in on the lateral connections 31, 32, as well as a setting element 38 for varying the phase of the field modes coupled in via the axial connection 33 are integrated in supply network 35.
When arrangement 30 is applied as intended, an electro-magnetic wave of mode TE11 is coupled in via each of the faUG-14-1998 13: 28 COLLRRD & ROE ' alb .5b5 ~t~e~~ r: em~ c~
lateral connections 31, 32. The azimuthal directional characteristic of the associated mixed mode of type TEllx/TElly has approximately the shape of an "eight" (8) and has a preferred axis along a line corresponding with the angle bisector between connections 31 and 32, with maximum emission existing along said preferred axis. The TENt basic mode is addit~.onally fed in on axial connection 33, said basic mode being superposed with the field modes coupled in by the lateral connections 31,_32 to form a TEM-TE11/TEllx/TElly--mixed mode. with the same phase ratio between the TEll-field modes, which are coupled in on connections 31, 32, and the TENT-basic mode, which is coupled in on connection 33, said mixed mode has the same preferred axis of maximum field distribution or maximum emission as the aforementioned TE1~/TEZly-mode. The phase ratio is mutually adjustable on connections 31, 32 as well as on axial connection 33 by means of the phase setting element 38 in supply network 35. fihe change of said phase ratio also Leads to a change of the preferred axis of maximum field distribution or maximum emission. In arrangement 30, an electronically controlled swinging of the main direction of radiation of the electromagnetic wave emitted by antenna 2 is effected in this way in any desired azimuthal direction.
The transmitting and receiving unit 40 shown in FIG. 5 consists in the manner described above of a biconical RUG-14=1998 13-28 COLLRRD & ROE -. X16 sb5 ~6~5 r.~5~~4 a antenna 2 as well as a resonator 3 actively connected to the latter, with a plurality of coupling connections being arranged on said resonator in the circumferential direction for feeding in electromagnetic oscillation modes. Transmitting and receiving unit 40 is additionally equipped with an~
electronic control unit 41. Transmitting and receiving unit 40, which is stationary.in the present case, is in radio communication with a mobile transmitting and receiving unit 43.
The directional characteristic of antenna 2 of transmitting and receiving unit 40 is adapted to the direction of maximum receiving power with the help of electronic control,unit 41, in the present exemplified embodiment to the main radiation direction 44 of the mobile transmitting and receiving unit 43.
For said purpose, main radiation direction 46 of the directional characteristic of antenna 2 of transmitting and receiving unit 40 is swiveled at predetermined time intervals acxoss the entire azimuth range of 360°, as indicated by arrows 47. This is accomplished by either engaging the coupling connections 10 one after the.:other in a predetermined circumferential direction for feeding in the oscillation modes, or by suitably addressing the coupling connections 10, which leads to a change in the amplitude and/or phase ratio of the electromagnetic oscillation modes coupled into resonator 3_ The receiving power is measua:ed in -this connection at predetermined azimuthal angle spacings and the azimuthal dependence of the receiving power is determined based on said measurement, and the direction of maximum receiving power is in turn computed based on said dependence. By suitably adjusting the amplitude and/or phase ratios of the oscillation modes coupled into resonator 3 of transmitting and receiving unit 90, or by changing the direction,in which the oscillation modes are coupled into the resonator, the main radiation direction 46 is subsequently adjusted in the direction of maximum receiving power.
With said method, it is possible without problems to cause main radiation direction 45 to follow the main radiation direction 44 of a moving transmitting and receiving unit 43 and to thus assure a constantly good reception.
In the exemplified embodiment, control electronics 41 is connected to an indicating electronics 49 for representing the azi.muthal dependence of the receiving power by sound or visually. Transmitting and receiving unit 40 is therefore particularly suitab7.e,for radiolocation.
FIG. 6 illustrated the principle of radio communication c between two transmitter receivers 40, 40", having an obstacle 52 positioned in between. A relay station 40' is used to avoid obstacle 52. Transmitter receivers 40, 40' 40", may be either fixed or mobile units.
FIG. 7 shows the application. of transmitting and receiving unit 40 in a so-called "point-to-multipoint" connection, AUG-14-1998 13=29 COLLARD & ROE _ 516 365 985 r.e'~i~4 _ CA 02246724 1998-08-17 where transmitting and receiving unit AO is simultaneously in radio contact with a plurality of transmitting and receiving units 43. For this purpose it is necessary only to select those oscillation modes for coupling into the resonator whose linear superposition leads to a directional characteristic with three main directions of radiation.
In the mobile radio sector, sector base station antennas are often used according to the state of the art so as to be able to define the area of radio supply in a more targeted manner. The sectors S3. 53', 53 " , 53 "' selected according to the state of the art are predetermined by the base station antenna configuration and cannot be changed rapidly and in any desired way. According to the invention, however, a radio sector is defined in each. case by a predetermined main radiation direction 54, 54', 54 " . such main radiation directions 54, 54', 54 " can be changed in any desired way over the entire azimuth range and can be optimally adapted in this way to the actual volume of radio traffic and its distribution in terms of space.
Finally, the application of two biconical antennas for realizing a combined local/angle diversity system is shown in FIG_ 8.
RUG-14-1998 13=29 COLLARD & ROE 516 365 9805 P.e8i24 The two transmitting and receiving~units 40, 40' axe arranged spaced from each other and are actively connected to an electronic control 54. The two transmitting and receiving units are controllable independently of one another by means of electronic control 54.
Transmitting and receiving units 40, 40' are controlled by the electronic controller in such a way that different directional characteristics 56, 5&' develop on the two transmitting and receiving units 40, 40'_ In the exemplified embodiment, the two directional characteristics 56, 56' have two identical main radiation directions 57, 57'. However, directional characteristic 56 is developed stronger in main radiation direction S7' than in main radiation direction 57, whereas directional characteristic 56' is developed stronger in main radiation direction 57 than in main radiation direction 57'. The receive signals of both transmitting and receiving units 40, 40' are detected by electronic control 54 and correlated with each other. Both the spatial separation of transmitting and receiving unit 40 and the different directional characteristic lead to different receive signals, and the correlation of said signals leads to a substantially enhanced reception especially with weak signals.
AUG-14-1998 13:29 COLLARD & ROE - 516 365 9885 P.09i24 Instead of the two transmitting and receiving units 40 shown in FIG. 8 it is possible to use one single biconical antenna 2 in order to achieve an angular diversity across all azimuth directions by realizing two receiving channels each having a different antenna directional characteristic.
_28-
In order to obtain a predetermined directional characteristic, the individual oscillation modes are coupled into the resonator, with a preset amplitude and/or phase ratio. The directional characteristic is variable also in a predetermined manner by changing the length of the resonator.
The direction of radiation can be advantageously changed also by coupling the oscillation modes into the resonator from a predetermined but variable azimuthal direction.
In addition to the transverse electromagnetic basic mode, the so-called TEM--mode, one or several higher modes of the TES,-type are usefully generated in the resonator and super-posed on.the basic mode. In particular, by superposing the TEM-mode with the T~11-mode, an exciting field is created which effects the development of a unilateral radiation characteristic on the antenna. When a higher oscillation mode is superposed on the TEM basic mode with a predetermined amplitude and phase ratio, an anisotropic directional characteristic with a predetermined main direction of radiation of the emitted electromagnetic wave is effected according to the method of the invention. By changing the phase ratio between the higher mode of oseillat3on and the TEM basic mode in a targeted way, a change takes place in the preferred direction of emission that is adapted to the given requirements.
According to another~advantageous development of the invention, a directional characteristic is generated on the antenna which has at least two different main directions of radiation. Thus a so-called "point-to-multipoint" application is possible; i.e., communication of the antenna with a plurality of other transmitting and/or receiving antennas.
The method of the invention differs from the method according to claim 1 in that the antenna is used as a-receiving antenna, whereby the main direction of radiation of a aransmitting~ 'antenna' .. . . . i.~:
communicating with the receiving antenna is determined at regular intervals ana the directional: characteristic of the receiving antenna is adjusted according to the~direction of maximum receiving power. The variation of the main direction of radiation in the detection of~the direction of maximum receiving power and in the new adjustment of the main direction of radiation takes place in an entirely simple manner by accordingly changing the amplitude and/or the phase ratio and/or the direction of azimuthal coupling of the oscillation modes into the resonator actively connected to the receiving antenna. Thus the main direction of radiation is adjustable in each case by electronic weasures and consequently such adjustments~can be carried out rapidly. The method according to the invention is thus suitable especially for application in mobile radio communication installations.
In said device, a resonator is provided with at least one coupling connection far coupling-in an electromagnetic field.
The resoriatox has to be operatable in this connection in excess mode, i.e., so that also higher electromagnetic:
oscillation modes can be generated in addition to the TEM-mode.
With suitable excitation, a electric field consisting.of a mix of modes develops in the resonator, and said field is used for exciting an antenna: The electromagnetic wave.: emitted from the antenna has a directional characteristic cowforming to RUG-14-1998 13:05 COLLRRD & ROE . 516 365 9805 P.09 the mix of modes generated in the resonator.
According to an advantageous further development, a single-conical or a biconical antenna serves as the aerial. Such antennas are known, for example from US 4,851,859, and are characterized by a transmitting and receiving capability that is azimuthally uniform over 360 degrees. Such antennas have been used heretofore for vmnidirectional transmissions. By exciting such an antenna with a directionally selective field of excitation, the transmission, too, takes place with a corresponding directionally selective radiation characteristic.
The application of such an antenna is advantageous primarily for the reason that it permits transmission in almost any desired azimuthal direction with dependence only upon the geometry of the exciting field - which is variable by simple electronic measures ~ without having to change the antenna arrangement in any way. The two halves of the single-conical or biconical antenna also may have different radial diameters, or the inner angles of the two conical haves may be different.
According to another advantageous further development, the resonator in which the electromagnetic oscillation modes are generated can be designed in such a way that it can be tuned by changing its length. The ratio at which the individual oscillation modes develop in the resonator relative to each other _g_ faUG-14-1998 13 = 06 COLLfaRD & ROE - 516 3659805 f . 10122 is variable in this way,.
A particularly simple resonator, which is advantageous especially when cooperating with a single conical or biconial antenna, is make available by a coaxial wave conductor_cahich can be operated in excess mode far generating high electro-magnetic oscillation modes. Furthermore, the inner and outer conductors. of a coaxial wave conductor can be connected without any problem to the two cones of a biconical antenna.
For developing well-defined electromagnetic oscillation modes it is necessary that the coaxial wave conductor has a termination at its end opposing~.ithe connection to the antenna.
Said termination may either consist df a short circuit, for example in the form of a metallic plate electrically connecting both conductors, or such termination is produced by a completely reflection-free arrangement.
ladvantageously, the electromagnetic field is coupled in via at least one coupling connection, which is arranged radially on the ..coaxial wave conduc.tor-on the outside. Reliable coupling of the electromagnetic modes into the resonator is achieved in this way. It is par-ricularly advantageous if the arrangement comprises a plurality of coupling connections, which are arranged in the circumferential di_reation of the coaxial wave conductor _g~
with the same angular spacings. In such an arrangement, the radiation.characteristics each having a different main direction of radiation can be obtained in a simple manner without changing the arrangement of the resonator by addressing different coupling connections depending on the desired direction of emission.
Alternatively to the lateral coupling of the electromagnetic 'field into the resonator coupling takes place by means of a ' coupling connection arranged at the end of the resonator opposing the connection to the antenna. Axial coupling-in is effected in this way.
Coaxial sleeves are suitable as reliable and low-radiation coupling connections.
\~.The electromagnetic field is coupled in via capacitive~and/or inductive coupling elemenfs. Coupling pins or dead-end feeders can be considered in this connection as capaeitive coupling elements, and. coupling loops or coils as inductive coupling .elements. It is particularly advantageous.
if such coupling elements are etched as conducting paths on a conductor board or applied in some other~~aay, whereby the ,10-r pc board is arranged in the resonator in a suitable way.
As.an alternative or to complete the coupling of the electromagnetic wave into the resonator by means of capacitive and/or inductive coupling elements, coupling of the electro-magnetic field takes place by means of one or a plurality of~hollow conductors, which are connected to the resonator on coupling slits and/or coupling holes.
The, coupling connections provided for coupling the electro-magnetic wave into the resonator are usefully connected to a supply network, byWeans of which the amplitudes and/or phases of~the coupled-in oscillation modes can be controlled as well.
This is particularly advantageous because the field distribution of the mixed mode resulting from the superposition of the oscillation modes, and thus also the directional characteristic of the electromagnetic wave emitted by the antenna due to excitation by a field of said mixed mode are dependent with particular sensitivity upon the amplitude and phase ratio of~
the basic oscillation. modes. A great variation width of adjustable directional characteristics is thus available owing to the separate controllability of the amplitudes and~phases.of the tuning modes coupled in.
According to one embodiment of the invention, a single-conical and/or biconical antenna AUG-14-1998 13~06 COLLARD &, ROE - 516 365 9805 P.13i22 is connected to a coaxial wave conductor, which has coupling connections for coupling in electromagnetic oscillation modes both radially on the outside and at its end disposed opposite the connection to the antenna. The coupling connections are connected to a supply network, by means of which the oscillation modes coupled in each can be varied in their amplitudes and/or phases independently of each other. In this connection, a coupling connection arranged opposite the antenna connection preferably serves for coupling in a TEM basic mode, and the other coupling connections serve fox coupling in higher, azimuthally anisotropic oscillation modes. The superposition of the azimuthally anisotropic oscillation modes leads to a directional characteristic of the emitted electromagnetic field that.!.has.one or a plurality of well-defined main directions of radiation_ The main direction of radiation is variably adjustable particularly by changing the phase relation between the azimuthally anisotropic oscillation modes and the TEM basic mode.
The arrangement consisting of the antEnna and the resonator is suitable not only for transmitting but also for receiving electromagnetic waves.
In an advantageous further development, the resonator and the antenna are actively connected to a control electronics, by means of which it is possible to determine a direction of AUG-14-1998 13~0 COLLARD & ROE - 516 365 9805 P.14i22 maximum azimuthal receiving capacity and to ahen adjust the main direction of radiation of the directional characteristic of the maximum receiving capacity accordingly by suitably varying the amplitude and/or the phase ratios and/or the direction of the azimuthal coupling of the oscillation modes.
The direction of maximum receiving capacity can be determined in this connection, for example in such a way that the main direction of radiation of the directional characteristic of the antenna is varied at predetermined time intervals and the outputs received from different azimuthal directions are compared. Owing to the fact that the main direction of radiation can be adjusted by only electronic measures it is possible to newly adjust the main direction of radiation again in a very rapid way, which is advantageous especially in applications in mobile or partly mobile radio communication installations.
According to another advantageous further~::de~~lopment, the control electronics - by means of which the direction of maximum azimuthal receiving capacity is determined - is actively connected to an indicator device, by means of which the azimuthal directional dependence of the receiving capacity is representable by sound or visually. Such a device is particularly suitable for radiolocation.
RUG-14-1998 13~07 COLLRRD & ROE 516 365 9805 P.15i22 The device as defined by the invention is suitable in a particularly advantageous manner as a relay station in a radio communications network. By suitably adjustir_g different main directions of radiation of the directional characteristic it is possible to simultaneously receive signals of a , transmitter as well as to transmit signals to a receiver other than the transmitter. The transmitter and the receiver do not have to be stationary at all in this connection; the rapid Y
electronic adjustability of the principal direction of radiation of the relay station rather permits also the application of the device as defined by the invention in a radio communications network consisting of mobile units_ According to yet another further development, the device as defined by the invention is used in a diversity system for receiving particularly weak signals or signals strongly interfered with. Zn this connection., the diversity consists of a separation between two antennas in terms of space, on the one hand, and of an individually variable directional characteristic of such two antennas, on the other. The correlation of the two receive signals is dependent upon the local separation, on the one hand, and additionally also on the different directional characteristic. The receiving capacity of the arrangement is increased overall by suitably combining the receive signals of both antennas electronically.
~14-.
The solution of the problem as defined by the invention may be also implemented as a radio communication system.
The radio communication system consists of at least two transmitting and receiving units, which each have a resonator provided with at least one coupling connection for coupling in an electromagnetic field, such resonator being actively connected to an antenna. When used as intended, the antenna emits electromagnetic waves with a directional characteristic corresponding with the field dependence of the electromagnetic oscillation modes linearly superposed in the resonator, and at the same time has a predetermined directional characteristic.
A control electronics aligns the main directions of radiation - of a transmitting and receiving unit with the main direction of radiation of transmitting and receiving units each being in radio contact with transmitting and receiving unit.
According to an advantageous further development,, the radio communication system has at least three transmitting-and receiving units, of~which at least one unit is applicable at the same time as a relay point..Due to the rapid electronic.
adjustability.of the main directions,of radiation, the radio communication system is suitable to a particularly high degree for application in radio-communications between mobile subscribers between each other, or between stationary subscribers on the one side and mobile subsc=fibers on the other. The relay a station, for example, may be arranged in a vehicle or on board of a helicopter.
In a particularly advantageous application, the-radi.o communication system is used in a mobile radio communication network, for example in a mobile telephone system. The special advantage of the radio communication system as defined by the invention lies zn.that due to the efficient spatial bunching by means of the electronic adjustment of the main directions of radiation of the participating transmitting and receiving units, the required transmitting power is reduced and the safety against listening-in is enhanced.
Brief Description of the Drawings The invention is explained in greater detail in the following with the help of -the attached .drawing, in which the following is shown schematically:
FIG. 1 shows a biconical antenna connected to a coaxial wave conductor.
FTG. .2 is a longitudinal center section.through the arrangement according to FIG. 1.
FIG. 3 is a sketch illustrating the principle of the method as defined by the invention with the help of field lines and directional characteristics.
... CA 02246724 2004-02-16 FIG. 4 shows a biconical antenna. with a connected coaxial wave conductor in another embodiment.
FIG. S is a sketch illustrating the principle of determination o~ a direction of maximum receiving power in radio communications between two transmitting and receiving units.
FZG. 6 is a sketch illustrating the principle of radio communication between two transmitting and receiving units with interconnection of a relay station.
FIG. 7 is a sketch~illust'rating the principle of radio communication between a~transmitting unit and a plurality o~
r.epe~ving units; and FIG. 8 is a sketch of,the principhe for explaining how the devices as defined by the invention are applied in a local/
anghe diversity system.
Detailed Description of the Preferred Embodiments ~In arrangement 1 shown in'FZGS. 1 and 2, a biconical antenna 2 is mounted on a coaxial wave conductor 3. The two halves 4, 5 of biconical antenna. 2 are. arranged rad.$ally symmetrically relative to each other and with respwet to coaxial wave conductor 3, opposing one another,with their conical AUG-14-1998 13=08 COLLHRD & ROE - 516 365 9805 P.19i22 widenings, and are connected to conical wave conductor 3 in the manner described in the following.
The lower half 5 of biconical antenna 2, said half being disposed directly adjacent to conical wave conductor 3, has the approximate shape of a circular truncated cone, the height of which is selected in such a way that its smallest radius approximately corresponds with the radius of outer conductor 7 of coaxial wave conductor 3. The area of lower half 5 of bioonical antenna 2 is bent .inwardly at the end with the smallest radial expanse and changes into a cylinder-shaped inner section 8, the radius of which corresponds with the one of the outer conductor 7, said inner section being electrically connected to the latter.
Upper half 4 of coaxial wave conductor 3 ,of .Iiiconical~
antenna 2,..~said lia3:f being farther :reriloved;:from coaxial wave conductor 3, changes into the tubular inner conductor 6 of coaxial wave conductor 3 in the manner of a ~unnel_ At the end of coaxial wave conductor 3 opposing biconical antenna 2, outer conductor 7 feeds into a electrically conductive, circular termination plate 9, which is electrically connected also to inner conductor 6.
The short circuyt existing in this way between inner conductor 6 and outer conductor 7 permits the development of preset oscillation modes in coaxial wave conductor 3. In this .. -18-AUG-14-1998 13-08 COLLRRD & ROE 516 365 9805 P.20i22 arrangement, the electrical field vectors oscillating zn the coaxial wave conductor between inner conductor 6 and outer conductor 7 in the radial direction are transformed by the conical widenings of the two antenna halves 4, 5 into an.oscillation mode axis-parallel with conical wave conductor 3 without losing any azimuthal field dependence that may be present. The electromagnetic wave emitted by biconical antenna 2 thus°exhibits an azimuthal dependence which corresponds with the azimuthal directional dependence of the electric field in coaxial wave conductor 3.
For coupling electromagnetic fields into coaxial wave conductor 3, a total of eight connection sleeves 10 are arranged radialiy on outer conductor 7 on the outer side in the present exemplified embodimenty said connection sleeves being of the same type among each other and each having the same angular spacing. Between connection sleeves 10, a conductor board 11 - which itself is not conductive - extends radially through the entire coaxial wave conductor 3, with capacitive and/or.inductove coupling elements - not shown in the drawing - in the form of etched-in conductor paths being arranged on said conductor board.
An electromagnetic wave is induced in coaxial wave conductor 3 by means of the coupling elements arranged on AUG-14-1998 13~08 COLLARD & ROE . 516 365 9805 P.~li conductor board 11. Coaxial wave conductor 3 is operated in this connection in excess mode. Further, higher oscillation conditions are generated in addition to the TEr2 basic mode.
The different oscillation modes of coaxial wave conductor 3 lead to corresponding oscillation modes in biconical antenna 2, which is electrically connected to said modes, and lead to corresponding electromagnetic waves in said antenna for emission.
It is explained in the following with the help of FIG. 3 on the example of superposition of two electromagnetic oscillation modes, the TEM basic mode and the TE11-mode, how a directionally selective transmission is effected by the antenna in an arrangement according to FTG. 1 or FIG. 2_ The electric field distribution in coaxial wave conductor 3 is radially symmetric in the case of the TEM basic mode.
Azimuthal radiation characteristic 20, which corresponds with said form o~ oscillation, shows an isotropic curve accordingly_ On the other hand, excitation of a TE1.1-mode leads to an anisotropic azimuthal dependence 21 in coaxial wave conductor 3 as well as to an anisotropic azimuthal radiation characteristic 22, which is characterized by an axis of maximum radial electric field distribution in coaxial wave conductor 3 and by a main direction of radiation -20' RUG-14-1998 13~28 COLLRRD & ROE . 516 ~b5 ~bd5 r.bG~G4 in radiation characteristic 22, in the present example along lines 90° - 270°. The electric field vectors oscillate in the coaxial wave conductor along said axis on both sides of inner conductor 6 in phase opposition.
With linear superposition of a TEM-mode with a TElI-mode, the component o~ the electric field of the TEll-mode oscillating in-phase with the TEM-mode is therefore amplified in coaxial wave conductor 3, whereas the inphase-opposed component is weakened, as shown by ~ield distribution 23 of the TEM-TEll-mixed mode. Radiation characteristic 24 corresponding with said mixed mode shows a single preferred direction of maximum emission, in the example in the 270°
direction.
When arrangement 1 is applied as intended, emission is achieved in this way in a predetermined direction. By addressing one of connections 10 in a controlled manner it is possible in this connection to vary the direction in azimuthal angles corresponding with the angular spacings of the individual connections Z0, whereby each addressing of one of connections leads to a same type of supezposition of the oscillation modes as described above, however, in each case with anatherw preferred direction_ In the case of the eight connections of arrangement l, eight different preferred directions can b~
_~l_ RUG-14-1998 13=28 COLLRRD & ROE 516 365 9805 -F.03i24 achieved in this way in the transmission of the electro-magnetic wave on antenna 2.
Arrangement 30 shown in FIG. 4 has a structure modified as compared to arrangement 1. Biconical antenna 2 and the coaxial wave conductor 3 are structured in the same way as in arrangement 1. l3owever, instead of the eight lateral connections 10, arrangement 30 has only two radial connections 31, 32 arranged at an angle of 90° relative to each other, said conr~ections being arranged radially on outer conductor 7 on the outer side, as well as an axial connection 33 at the end of coaxial wave conductor 3 opposing the antenna. Connections 31, 32, 33 are connected to a supply network 35, which supplies the electria.energy reguired for coupling in predetermined electromagnetic oscillation modes.
Setting elements 36, 37 for controlling the amplitudes of the electromagnetic field modes coupled in on the lateral connections 31, 32, as well as a setting element 38 for varying the phase of the field modes coupled in via the axial connection 33 are integrated in supply network 35.
When arrangement 30 is applied as intended, an electro-magnetic wave of mode TE11 is coupled in via each of the faUG-14-1998 13: 28 COLLRRD & ROE ' alb .5b5 ~t~e~~ r: em~ c~
lateral connections 31, 32. The azimuthal directional characteristic of the associated mixed mode of type TEllx/TElly has approximately the shape of an "eight" (8) and has a preferred axis along a line corresponding with the angle bisector between connections 31 and 32, with maximum emission existing along said preferred axis. The TENt basic mode is addit~.onally fed in on axial connection 33, said basic mode being superposed with the field modes coupled in by the lateral connections 31,_32 to form a TEM-TE11/TEllx/TElly--mixed mode. with the same phase ratio between the TEll-field modes, which are coupled in on connections 31, 32, and the TENT-basic mode, which is coupled in on connection 33, said mixed mode has the same preferred axis of maximum field distribution or maximum emission as the aforementioned TE1~/TEZly-mode. The phase ratio is mutually adjustable on connections 31, 32 as well as on axial connection 33 by means of the phase setting element 38 in supply network 35. fihe change of said phase ratio also Leads to a change of the preferred axis of maximum field distribution or maximum emission. In arrangement 30, an electronically controlled swinging of the main direction of radiation of the electromagnetic wave emitted by antenna 2 is effected in this way in any desired azimuthal direction.
The transmitting and receiving unit 40 shown in FIG. 5 consists in the manner described above of a biconical RUG-14=1998 13-28 COLLRRD & ROE -. X16 sb5 ~6~5 r.~5~~4 a antenna 2 as well as a resonator 3 actively connected to the latter, with a plurality of coupling connections being arranged on said resonator in the circumferential direction for feeding in electromagnetic oscillation modes. Transmitting and receiving unit 40 is additionally equipped with an~
electronic control unit 41. Transmitting and receiving unit 40, which is stationary.in the present case, is in radio communication with a mobile transmitting and receiving unit 43.
The directional characteristic of antenna 2 of transmitting and receiving unit 40 is adapted to the direction of maximum receiving power with the help of electronic control,unit 41, in the present exemplified embodiment to the main radiation direction 44 of the mobile transmitting and receiving unit 43.
For said purpose, main radiation direction 46 of the directional characteristic of antenna 2 of transmitting and receiving unit 40 is swiveled at predetermined time intervals acxoss the entire azimuth range of 360°, as indicated by arrows 47. This is accomplished by either engaging the coupling connections 10 one after the.:other in a predetermined circumferential direction for feeding in the oscillation modes, or by suitably addressing the coupling connections 10, which leads to a change in the amplitude and/or phase ratio of the electromagnetic oscillation modes coupled into resonator 3_ The receiving power is measua:ed in -this connection at predetermined azimuthal angle spacings and the azimuthal dependence of the receiving power is determined based on said measurement, and the direction of maximum receiving power is in turn computed based on said dependence. By suitably adjusting the amplitude and/or phase ratios of the oscillation modes coupled into resonator 3 of transmitting and receiving unit 90, or by changing the direction,in which the oscillation modes are coupled into the resonator, the main radiation direction 46 is subsequently adjusted in the direction of maximum receiving power.
With said method, it is possible without problems to cause main radiation direction 45 to follow the main radiation direction 44 of a moving transmitting and receiving unit 43 and to thus assure a constantly good reception.
In the exemplified embodiment, control electronics 41 is connected to an indicating electronics 49 for representing the azi.muthal dependence of the receiving power by sound or visually. Transmitting and receiving unit 40 is therefore particularly suitab7.e,for radiolocation.
FIG. 6 illustrated the principle of radio communication c between two transmitter receivers 40, 40", having an obstacle 52 positioned in between. A relay station 40' is used to avoid obstacle 52. Transmitter receivers 40, 40' 40", may be either fixed or mobile units.
FIG. 7 shows the application. of transmitting and receiving unit 40 in a so-called "point-to-multipoint" connection, AUG-14-1998 13=29 COLLARD & ROE _ 516 365 985 r.e'~i~4 _ CA 02246724 1998-08-17 where transmitting and receiving unit AO is simultaneously in radio contact with a plurality of transmitting and receiving units 43. For this purpose it is necessary only to select those oscillation modes for coupling into the resonator whose linear superposition leads to a directional characteristic with three main directions of radiation.
In the mobile radio sector, sector base station antennas are often used according to the state of the art so as to be able to define the area of radio supply in a more targeted manner. The sectors S3. 53', 53 " , 53 "' selected according to the state of the art are predetermined by the base station antenna configuration and cannot be changed rapidly and in any desired way. According to the invention, however, a radio sector is defined in each. case by a predetermined main radiation direction 54, 54', 54 " . such main radiation directions 54, 54', 54 " can be changed in any desired way over the entire azimuth range and can be optimally adapted in this way to the actual volume of radio traffic and its distribution in terms of space.
Finally, the application of two biconical antennas for realizing a combined local/angle diversity system is shown in FIG_ 8.
RUG-14-1998 13=29 COLLARD & ROE 516 365 9805 P.e8i24 The two transmitting and receiving~units 40, 40' axe arranged spaced from each other and are actively connected to an electronic control 54. The two transmitting and receiving units are controllable independently of one another by means of electronic control 54.
Transmitting and receiving units 40, 40' are controlled by the electronic controller in such a way that different directional characteristics 56, 5&' develop on the two transmitting and receiving units 40, 40'_ In the exemplified embodiment, the two directional characteristics 56, 56' have two identical main radiation directions 57, 57'. However, directional characteristic 56 is developed stronger in main radiation direction S7' than in main radiation direction 57, whereas directional characteristic 56' is developed stronger in main radiation direction 57 than in main radiation direction 57'. The receive signals of both transmitting and receiving units 40, 40' are detected by electronic control 54 and correlated with each other. Both the spatial separation of transmitting and receiving unit 40 and the different directional characteristic lead to different receive signals, and the correlation of said signals leads to a substantially enhanced reception especially with weak signals.
AUG-14-1998 13:29 COLLARD & ROE - 516 365 9885 P.09i24 Instead of the two transmitting and receiving units 40 shown in FIG. 8 it is possible to use one single biconical antenna 2 in order to achieve an angular diversity across all azimuth directions by realizing two receiving channels each having a different antenna directional characteristic.
_28-
Claims (30)
1. A method for omnidirectional emission and reception of electromagnetic waves, comprising the steps of:
a) providing a resonator having a length and a plurality of naturally occurring oscillating modes including a transverse electromagnetic TEM basic mode and associated transverse electrical TEm1 higher modes, said TEM basic mode and each of said TEm1 higher modes having variable parameters;
b) operating said resonator in an excess mode for linearly superimposing said TEM
basic mode with at least one of said TEm1 higher modes and generating a mixed mode direction selective excites field having a geometry dependent on said variable parameters;
c) applying said excites field to a non-directional antenna to induce directional antenna characteristics including a maximum receiving power direction and a main direction of radiation; and d) controlling angular positions of said antenna characteristics based on said geometry of said excites field.
a) providing a resonator having a length and a plurality of naturally occurring oscillating modes including a transverse electromagnetic TEM basic mode and associated transverse electrical TEm1 higher modes, said TEM basic mode and each of said TEm1 higher modes having variable parameters;
b) operating said resonator in an excess mode for linearly superimposing said TEM
basic mode with at least one of said TEm1 higher modes and generating a mixed mode direction selective excites field having a geometry dependent on said variable parameters;
c) applying said excites field to a non-directional antenna to induce directional antenna characteristics including a maximum receiving power direction and a main direction of radiation; and d) controlling angular positions of said antenna characteristics based on said geometry of said excites field.
2. The method of claim 3, wherein said variable parameters can be independently adjusted and include one of a phase ratio between said basic mode and a higher mode, the directions of the azimuthal couplings of said basic mode and said higher mode, amplitudes of said basic mode and said higher mode, said length of said resonator, and combinations thereof.
3. The method of claim 1, wherein said transverse electric higher mode is TE11.
4. The method of claim 1, wherein said step of controlling is performed electronically.
5. The method of claim 1, wherein said naturally occurring oscillating modes are capacitively coupled to said resonator.
6. The method of claim 1, wherein said naturally occurring oscillating modes are inductively coupled to said resonator.
7. The method of claim 1, wherein two higher modes having preselected azimuthal angles are superimposed over said basic mode in said resonator for generating two directional antenna characteristics with said angular positions dependent on said azimuthal angles, and wherein said step of controlling is performed based on the amplitude ratio and the phase ratio of said two higher modes.
8. The method of claim 7, further comprising:
- generating two antenna characteristics at two separate locations;
- aligning both directions of maximum receiving power with a transmitting source;
- correlating signals received at each location for optimizing reception of weak signals based on a spatial-angular diversity.
- generating two antenna characteristics at two separate locations;
- aligning both directions of maximum receiving power with a transmitting source;
- correlating signals received at each location for optimizing reception of weak signals based on a spatial-angular diversity.
9. The method of claim 8, wherein said two antenna characteristics are generated and said signals received at the same location for optimizing reception of weak signals based on a local-angular diversity.
10. The method of claim 1, further comprising:
- generating a plurality of directional antenna characteristics;
- swiveling each of said antenna characteristics across a service area;
- computing said direction of maximum receiving power by comparing the power of a plurality of received signals from a transmitting source;
- constantly monitoring the relationship between the power of said received signals and said antenna characteristics; and - adjusting said variable parameters for aligning said main direction of radiation based on said direction of maximum receiving power and radio locating said transmitting source.
- generating a plurality of directional antenna characteristics;
- swiveling each of said antenna characteristics across a service area;
- computing said direction of maximum receiving power by comparing the power of a plurality of received signals from a transmitting source;
- constantly monitoring the relationship between the power of said received signals and said antenna characteristics; and - adjusting said variable parameters for aligning said main direction of radiation based on said direction of maximum receiving power and radio locating said transmitting source.
11. A radiating device for omnidirectional emission and reception of electromagnetic waves, comprising:
a resonator including a tubular outer conductor and a coaxial wave conductor, said resonator having length defined between an active end and a second end and a plurality of naturally occurring oscillating modes including a transverse electromagnetic TEM basic mode and associated transverse electrical TEm1 higher modes, said TEM basic mode and each of said TEm1 higher modes having variable parameters, termination means defined at said second end for electrically connecting said outer connector and said coaxial wave connector, a coupling stub disposed at said second end for coupling said basic mode to said coaxial wave guide and operating said resonator in an excess mode, at least one coupling element radially arranged in said outer conductor for coupling at least one of said TEm1 higher modes to said resonator, linearly superimposing said TEM basic mode with said at least one of said TEm9 higher modes, and generating a mixed mode direction selective exciter field having a geometry dependent on said variable parameters, a non-directional antenna connected to said active end of said resonator for receiving said exciter field and inducing directional antenna characteristics including a maximum receiving power direction and a main direction of radiation, wherein angular positions of said antenna characteristics are controlled based on said geometry of said exciter field.
a resonator including a tubular outer conductor and a coaxial wave conductor, said resonator having length defined between an active end and a second end and a plurality of naturally occurring oscillating modes including a transverse electromagnetic TEM basic mode and associated transverse electrical TEm1 higher modes, said TEM basic mode and each of said TEm1 higher modes having variable parameters, termination means defined at said second end for electrically connecting said outer connector and said coaxial wave connector, a coupling stub disposed at said second end for coupling said basic mode to said coaxial wave guide and operating said resonator in an excess mode, at least one coupling element radially arranged in said outer conductor for coupling at least one of said TEm1 higher modes to said resonator, linearly superimposing said TEM basic mode with said at least one of said TEm9 higher modes, and generating a mixed mode direction selective exciter field having a geometry dependent on said variable parameters, a non-directional antenna connected to said active end of said resonator for receiving said exciter field and inducing directional antenna characteristics including a maximum receiving power direction and a main direction of radiation, wherein angular positions of said antenna characteristics are controlled based on said geometry of said exciter field.
12. The device of claim 11, wherein said antenna is a single-conical antenna.
13. The device of claim 11, wherein said antenna is a bi-conical antenna.
14. The device of claim 11, wherein said termination means is a metallic plate.
15. The device of claim 11, wherein said termination means is a reflection-free arrangement.
16. The device of claim 11, wherein said variable parameters can be independently adjusted and include one of a phase ratio between said basic mode and a higher mode, the directions of the azimuthal couplings of said basic mode and said higher mode, amplitudes of said basic mode and said higher mode, said length of said resonator, and combinations thereof.
17. The device of claim 11, further comprising a control unit for electronically controlling said variable parameters.
18. The device of claim 11, wherein said coupling element is capacitively coupled to said resonator.
19. The device of claim 11, wherein said coupling element is inductively coupled to said resonator.
20. The device any one of claims 18 or 19, wherein said coupling element is a conductor path formed on a conductor board.
21. The device of claim 11, including eight coupling elements radially arranged and equally spaced on said outer conductor.
22. The device of claim 21, wherein said coupling elements are connected to a supply network with integrated elements for independently adjusting said variable parameters.
23. The device of claim 22, further comprising two antennas at two distant fixed locations for generating two antenna characteristics and aligning both directions of maximum receiving power with a transmitting source;
a central control unit for correlating signals received at each location and optimizing reception of weak signals based on a spatial-angular diversity.
a central control unit for correlating signals received at each location and optimizing reception of weak signals based on a spatial-angular diversity.
24. The device of claim 23, wherein said two antenna characteristics are generated by a single antenna provided at a fixed location and said signals are received on two separate channels at said fixed location for optimizing reception of weak signals based on a local-angular diversity.
25. A radio communications system having at least two transmitting/receiving units, each unit having a radiation device comprising:
a resonator including a tubular outer conductor and a coaxial wave conductor, said resonator having length defined between an active end and a second end and a plurality of naturally occurring oscillating modes including a transverse electromagnetic TEM basic mode and associated transverse electrical TEm1 higher modes, said TEM basic mode and each of said TEm1 higher modes having variable parameters, termination means defined at said second end for electrically connecting said outer connector and said coaxial wave connector, a coupling stub disposed at said second end for coupling said basic mode to said coaxial wave guide and operating said resonator in an excess mode, at least one coupling element radially arranged in said outer conductor for coupling at least one of said TEm1 higher modes to said resonator, said coaxial wave guide for linearly superimposing said TEM basic mode with said at least one of said TEm1 higher modes, said resonator for generating a mixed mode direction selective exciter field having a geometry dependent on said variable parameters, a non-directional antenna connected to said active end of said resonator for receiving said exciter field inducing directional antenna characteristics including a maximum receiving power direction and a main direction of radiation, a control unit for electronically controlling said variable parameters and modifying said variable geometry based on said variable parameters for selective orientation of said antenna characteristics, whereby, directional radio transmissions of signals is performed along said main direction of radiation, and directional radio reception of signals is performed along said direction of maximum receiving power.
a resonator including a tubular outer conductor and a coaxial wave conductor, said resonator having length defined between an active end and a second end and a plurality of naturally occurring oscillating modes including a transverse electromagnetic TEM basic mode and associated transverse electrical TEm1 higher modes, said TEM basic mode and each of said TEm1 higher modes having variable parameters, termination means defined at said second end for electrically connecting said outer connector and said coaxial wave connector, a coupling stub disposed at said second end for coupling said basic mode to said coaxial wave guide and operating said resonator in an excess mode, at least one coupling element radially arranged in said outer conductor for coupling at least one of said TEm1 higher modes to said resonator, said coaxial wave guide for linearly superimposing said TEM basic mode with said at least one of said TEm1 higher modes, said resonator for generating a mixed mode direction selective exciter field having a geometry dependent on said variable parameters, a non-directional antenna connected to said active end of said resonator for receiving said exciter field inducing directional antenna characteristics including a maximum receiving power direction and a main direction of radiation, a control unit for electronically controlling said variable parameters and modifying said variable geometry based on said variable parameters for selective orientation of said antenna characteristics, whereby, directional radio transmissions of signals is performed along said main direction of radiation, and directional radio reception of signals is performed along said direction of maximum receiving power.
26. The radio communications system of claim 25, wherein said direction of maximum receiving power which is computed based on measuring the power of a plurality of received signals using different antenna characteristics.
27. The radio communications system of claim 25, used in a mobile telephone system.
28. The radio communications system of claim 25, wherein said variable parameters are so selected to generate said antenna characteristics with at least two main directions of radiation for point-to-multipoint communications.
29. The radio communications system of claim 27, used as a relay point.
30. The device of claim 29, wherein said relay point is airborne.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19652595A DE19652595C2 (en) | 1996-12-18 | 1996-12-18 | Method and device for directionally selective radiation of electromagnetic waves |
| DE19652595.0 | 1996-12-18 | ||
| PCT/DE1997/002914 WO1998027612A1 (en) | 1996-12-18 | 1997-12-13 | Method and device for directionally selective emission of electromagnetic waves |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2246724A1 CA2246724A1 (en) | 1998-06-25 |
| CA2246724C true CA2246724C (en) | 2005-05-03 |
Family
ID=7815073
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002246724A Expired - Fee Related CA2246724C (en) | 1996-12-18 | 1997-12-13 | Method and device for directional emission and reception of electromagnetic waves |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0885472B1 (en) |
| AU (1) | AU723226B2 (en) |
| CA (1) | CA2246724C (en) |
| DE (2) | DE19652595C2 (en) |
| WO (1) | WO1998027612A1 (en) |
| ZA (1) | ZA9711232B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9907317D0 (en) * | 1999-03-31 | 1999-05-26 | Univ St Andrews | Antenna system |
| DE10012790C2 (en) * | 2000-03-14 | 2002-04-04 | Univ Dresden Tech | Device for directionally selective transmission and reception of electromagnetic waves |
| DE10012789C1 (en) * | 2000-03-14 | 2001-05-17 | Univ Dresden Tech | Directional transmission and reception device for electromagnetic waves has one or 2 antenna cones and energizing group with upper and lower plates, central reflector and peripheral energizing elements |
| WO2001069720A1 (en) * | 2000-03-14 | 2001-09-20 | Technische Universität Dresden | Device for transmitting and receiving electromagnetic waves in a route-selective manner |
| US20220166130A1 (en) * | 2020-11-25 | 2022-05-26 | Raytheon Company | Mitigation of ripple in element pattern of geodesic antenna |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2954558A (en) * | 1958-03-20 | 1960-09-27 | Richard C Honey | Omnidirectional antenna systems |
| GB889611A (en) * | 1960-05-09 | 1962-02-21 | Antenna Systems Inc | Electrically steerable horn antenna system |
| US3453621A (en) * | 1966-07-08 | 1969-07-01 | Hughes Aircraft Co | Dual mode receiving and transmitting antenna |
| US4005379A (en) * | 1975-11-04 | 1977-01-25 | Lockheed Electronics Co., Inc. | R.F. power distribution network for phased antenna array |
| US4947178A (en) * | 1988-05-02 | 1990-08-07 | Lotfollah Shafai | Scanning antenna |
| US4851859A (en) * | 1988-05-06 | 1989-07-25 | Purdue Research Foundation | Tunable discone antenna |
| US5134420A (en) * | 1990-05-07 | 1992-07-28 | Hughes Aircraft Company | Bicone antenna with hemispherical beam |
-
1996
- 1996-12-18 DE DE19652595A patent/DE19652595C2/en not_active Expired - Fee Related
-
1997
- 1997-12-13 CA CA002246724A patent/CA2246724C/en not_active Expired - Fee Related
- 1997-12-13 AU AU57479/98A patent/AU723226B2/en not_active Ceased
- 1997-12-13 DE DE59709271T patent/DE59709271D1/en not_active Expired - Fee Related
- 1997-12-13 WO PCT/DE1997/002914 patent/WO1998027612A1/en active IP Right Grant
- 1997-12-13 EP EP97953624A patent/EP0885472B1/en not_active Expired - Lifetime
- 1997-12-15 ZA ZA9711232A patent/ZA9711232B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| EP0885472B1 (en) | 2003-02-05 |
| DE19652595C2 (en) | 2001-10-11 |
| CA2246724A1 (en) | 1998-06-25 |
| AU723226B2 (en) | 2000-08-24 |
| DE19652595A1 (en) | 1998-06-25 |
| EP0885472A1 (en) | 1998-12-23 |
| AU5747998A (en) | 1998-07-15 |
| DE59709271D1 (en) | 2003-03-13 |
| ZA9711232B (en) | 1998-09-02 |
| WO1998027612A1 (en) | 1998-06-25 |
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| EEER | Examination request | ||
| MKLA | Lapsed |