FR2724492A1 - OMNIDIRECTIONAL EMISSION-RECEPTION ANTENNA SYSTEM MULTIPOLARIZATION WITH SUBSTANTIALLY CIRCULAR RADIATION DIAGRAM - Google Patents

Abstract

The invention relates to a multipolarization omnidirectional transceiver antenna system. It comprises a first (1) unidirectional radio antenna in a first direction defined by two orthogonal planes, one of the planes defining a first plane (C) and a second unidirectional radio antenna (2) in a second direction defined by two orthogonal planes , one of the planes defining a second plane (B). The first (1) and the second antenna (2) are placed so that the first and the second plane being orthogonal and the first and the second direction being orthogonal, we thus obtain an omnidirectional radiation pattern formed by a bidirectional radiation pattern in a third plane (A), which, orthogonal to the first and second plane, is formed by a main plane of the first and of the second antenna and by a unidirectional radiation pattern in the first and in the second plane. A coupling circuit (3) ensures a combination of amplitude and phase of the reception signals e1, e2 to obtain a circular radiation pattern. Application to transmitting devices, or transceivers, for example.

Description

i

  OMNIDIRECTIONAL TRANSMIT-RECEPTION ANTENNA SYSTEM

  MULTIPOLARIZATION WITH RADIATION DIAGRAM

SENSIBLY CIRCULAR

  The invention relates to an antenna system for transmitting

  omnidirectional multi-polarization reception-reception with a substantially circular radiation pattern, usable

  on transceivers or single receivers

used in paging.

  In paging systems, such as the

  R.D.S. system for "Radio Data System" in English

  Saxon, digital data management or use of this network are broadcast on the wave carrier of a signal of

  frequency modulation broadcasting of band II.

  The data disseminated can be very diverse in nature and is usually broadcast as messages

intended for subscribers.

  Today, paging is a means of communication that is widely used by a category of users who are often called upon to

  various means of locomotion, in geographical

very varied.

  In general, the receiver or transmitter / receiver

  tor, is intended to be worn by its user, either inside a jacket pocket or for example hung

at his belt.

  The user ignores and does not care whether the receiver, or the transceiver, is oriented correctly vis-à-vis the transmitter that broadcasts the messages. Indeed, the receivers or transceivers are very compact and normally equipped with an antenna

  which determines their dimensional characteristics.

  the. This antenna, sensitive in general to the magnetic component of the electromagnetic wave carrier, component H, is most often constituted by a metal frame

  very selective and optimized in gain, which gives the year

  thus formed a radiation pattern of the type

  unidirectional, having a good directivity.

  In order for the reception and, where appropriate, the

  If it is efficient, it is necessary that the orientation of this type of conventional antenna be performed as a function of the polarization of the carrier wave. The polarization of the waves

  issued by the facilities of the broadcasters, or radiotele

  lephonia, is in general either horizontal or vertical,

  very rarely circular or oblique.

  In the case where such a conventional antenna is not oriented accordingly, it can not allow to receive the polarized carrier wave as mentioned above,

  which leads to a detected signal loss not neglected

  ble, of the order of 20dB to 35dB when the orientation of the antenna is in quadrature with respect to the preferred axis

polarization of the field.

  In addition, this type of antenna does not have, in

  because of its unidirectional radiation pattern

  nel, an ability to receive, or transmit, radio signals in all azimuthal directions, this

  which normally also requires the user to

  receiver, or transceiver, in the horizontal plane. At best, this type of antenna, as shown in FIG. 1 for a metal frame antenna, with or without a ferrite core, presents a unidirectional radiation pattern in two orthogonal planes, the antennas then being placed that one of the planes is the horizontal plane, the other plane, vertical, in front of

  correspond to the plane of polarization of the electromagnetic wave

  spread, which of course implies two orienta-

for optimal reception.

  The present invention aims to overcome the aforementioned drawbacks, by implementing an omnidirectional transmission-reception antenna system with a substantially circular radiation pattern for which the contingencies relating to the orientation of the antenna system for a reception, or emission-reception, optimal, are

substantially removed.

  Another object of the present invention is, in particular, the implementation of a transmitting-receiving antenna system having a substantially circular radiation pattern in a plane, the horizontal plane. Another object of the present invention is, in

  In addition, the implementation of a transmission antenna system

  reception having a unidirectional radiation pattern

  two other plans, the three plans being

orthogonal each to each.

  The omnidirectional transceiver antenna system

  recessive with a substantially circular radiation pattern

  The subject of the present invention is remarkable in that

  it includes a first unidirectional radio antenna

  recurrent in a first direction defined by two orthogonal planes, forming principal planes of this antenna, one of the planes defining a first plane, and a second unidirectional radio antenna with respect to a second direction defined by two orthogonal planes, forming principal planes of this antenna, one of the plans defining a second plane. The first and second antennas are positioned so that the first and second planes are orthogonal, the first and second directions are orthogonal. The antenna system thus formed has a bidirectional radiation pattern in a third plane, orthogonal to the first and second

  plan and formed by a master plan of the first respec-

  second antenna, and a unidirectional radiation pattern in the first and second planes, respectively. The first and second radio antennas each provide a first and a second radio receive signal respectively. A coupling circuit of the first and second antennas provides the combination of amplitude and / or phase of the first and the second reception signal to generate a resultant reception signal whose radiation pattern corresponds to the system of reception. 'transceiver antennas is

  substantially circular in the third plane.

  The antenna system, object of the present invention

  is applied to paging and, more generally, to radiocommunication or mobile radiotelephony.

  It will be better understood by reading the description

  and to the observation of the drawings in which, in addition to FIG. 1 relating to the prior art, FIGS. 2a, 2b, 2c, 2d, 2e and 2f represent

  different antenna radiation patterns

  of the antenna system and the antenna system, object of the present invention, - Figures 3a and 3b show a practical embodiment of the antenna system, object of the present invention,

  FIGS. 4a, 4b and 4c represent the diagrams

  three of the orthogonal planes of the antenna system, object of the invention, as shown in FIGS. 3a, 3b; FIG. 5a represents the orientation of an antenna system according to the invention with respect to the direction of polarization of an incident carrier wave, - Figure 5b shows a block diagram of the coupling circuit of the antenna system, object of the present invention, - Figures 6a and 6b show a first and a second embodiment of an antenna coupling circuit, - Figures 7a and 7b show diagrams

obtained radiation.

  A more detailed description of an antenna system

  omnidirectional transmission-reception pattern with a substantially circular radiation pattern, in accordance with the subject of the present invention, will now be given in connection with

with Figures 2a to 2e and 2f.

  In accordance with the above figures, it is indicated that the antenna system, object of the present invention, has a first radio antenna, denoted 1, unidirectional in a first direction, this direction, denoted OX in Figure 2a, being defined by two planes orthogonal, plans OX, OZ respectively OX, OY. The above-mentioned planes form the main planes of this antenna 1, one of the planes, the plane OX, OZ defining a first plane,

noted C in Figure 2a.

  The antenna system, object of the present invention

  also includes a second radio antenna

  that unidirectional, noted 2, in a second direction, the direction OY in Figure 2b, this direction being defined by two orthogonal planes, OX, OY, respectively

  OY, OZ. These two planes form the main planes of the antenna.

  No. 2, one of the planes, the plane OY, OZ defining a second plane, noted B in Figure 2b. The first 1 and the second antenna 2 are placed in the vicinity of each other.

  way that the first C and the second plane B being orthogonal

  the first and second OX directions, respectively

  OY are also orthogonal. This allows to obtain

  for the antenna system 1,2 a radiation pattern

  substantially omnidirectional, formed by a bidirectional radiation pattern in a third plane A, as shown in Figure 2c. The plane A is orthogonal to the first and second planes and is formed by a main plane of the first respectively of the second antenna 1,2. The substantially omnidirectional radiation pattern of the antenna system thus formed also includes a unidirectional radiation pattern in the first C respectively in the second B plane, and

  as shown in Figures 2e and 2d.

  As shown in FIG. 2f, the first and second radio antennas each deliver a

  first and second respectively a second radio signal

reception desk.

  Finally, a coupling circuit 3 makes it possible to ensure the combination in amplitude and / or in phase of the first el and the second e2 reception signal in order to generate a resultant reception signal including the radiation pattern for the antenna system. corresponding transmission-reception, is substantially circular in the third plane A. It is of course understood that the antenna system, object of the present invention, can be used both at the reception and the emission, in because of the dual character of the radiation pattern in reception, respectively in emission, these radiation patterns being, according to the classical theory of antennas, identical to the emission

and at the reception.

  Of course, in the context of a reception device

  paging function, the transmission function is not

  necessary, which can then be deleted.

  A more detailed description of an antenna system

  An omnidirectional node with a substantially circular radiation pattern, which is the subject of the present invention, will now be given in conjunction with FIGS. 3a and 3b in the nonlimiting context of an application to radio paging by

example.

  As shown in FIG. 3a, the first antenna 1 is a metal frame antenna surrounding the actual body of the receiver R and the second antenna 2 is a ferrite core frame antenna. The metal frame antenna 1 for example surrounds the receiver circuits R, as shown in FIG. 3a, and is housed in the housing, not shown, of the receiving apparatus, which of course comprises a

  P battery power supply.

  The second antenna 2 also comprises a metal frame 20 which is further associated with a ferrite core 21. The second ferrite core antenna is placed in the vicinity of one of the sides of the metal frame

  constituent of the first antenna 1 for example.

  The configuration thus produced makes it possible, of course, for a given position of the receiver in space, to receive in all the azimuth positions, that is to say for any orientation of the receiver in the plane A, a suitable signal level thanks to orthogonal disposition of polar radiation patterns relating to

  each of the antennas, as shown in Figure 2c.

  The tuning of each antenna on the frequency of the incident carrier wave can be achieved by means of variable capacity diodes, not shown in the drawing; In FIG. 3b, there is shown, for the mode of

  embodiment of FIG. 3a, the orthogonal induction fluxes

  nals received by the first 1 and the second antenna 2 in the directions OX and OY. It is thus understood that, in the representation of FIG. 3b, the plane B is the plane of the sheet containing FIG. 3b, the plane A is a horizontal plane orthogonal to the plane of the sheet containing FIG. 3b and the plane C is a vertical plane orthogonal to the plane of the sheet containing Figure 3b. The reference OXYZ, respectively O'X'Y'Z 'corresponds to the oxyz mark of

  Figures 2a to 2e. In FIGS. 4a, 4b and 4c, there is shown

  felt the polar patterns of respective radiation received by the first and the second antenna in the directions

OX and OY.

  It is thus understood that the antenna system, object of the present invention, offers the possibility of a quasi-omnidirectional reception in the horizontal plane A thanks to the coupling circuit 3, which allows, thanks to an electronic system which will be described here. -after in connection with Figures 5a, 5b and following, to perform a combination of amplitude and / or phase of the first el and the

second e2 reception signal.

  FIG. 5a shows a transmitting / receiving antenna system according to the subject of the present invention, composed of two antennas tuned separately and perpendicular to each other, the first 1 and the second antenna 2 respectively. as previously shown in Figure 3b for example. It is of course considered that the first and the second antenna 1, 2 are tuned to the same frequency, that of the incident carrier wave, under conditions as described

previously in the description.

  The first 1 and the second antenna 2 are

  These are subjected to an electromagnetic field of vertically polarized magnetic component, as shown in FIG. 5a. For an incident magnetic component B at an angle p with the axis Ox as represented in FIG. 5a, the amplitudes of the first el and the second e2 reception radio signal are respectively established.

  as follows. The magnetic fluxes 1 respectively

  2 crossing the first and the second antenna respectively are given by the relations: = 1-S, = B1.S1cos (r / 2-P) = B1.Slsing

2 = B1. S2 = UrB1. S2cosP.

  In the aforementioned relations, it is indicated that the vector B1 represents the magnetic component of the electromagnetic field of amplitude B1, S1 and S2 represent the oriented surfaces of the first respectively second antenna 1,2 with respect to the wave vector P of the incident wave, S, and S2 representing the value of the surfaces of the

  first respectively second antenna 1,2.

  The first and the second reception radio signal el and e2 are then written: ## EQU1 ## where: ## EQU1 ##

  e2 = - d42 / dt = jWrpoHOS2coS.J (t.f).

  In the aforementioned relations, it is indicated that p. represents the permeability of the vacuum, Pr the relative permeability of the constituent magnetic material of the core of the second antenna 2, where the term of the pulses of the carrier wave

  incident, t time and T a phase term.

  According to a particularly advantageous aspect of the antenna system, object of the present invention,

  this consists in introducing, on radio signals

  receiver groups el and e2, a phase shift term

  relative * in order to compensate for the term

  duit by the inclination of the angle p of the polarization direction of the incident electromagnetic wave by

  relative to the orientation of the antenna system.

  For a first and second antenna 1,2 for which the geometry and the resulting radio parameters satisfy the following relation (5): Pr S2 = k Sl, ka 0, the sum of the first and second radio signals of reception e1, e2 is written, according to the relation (6): el + e2 eJ6 = jAO (sing + k cosp e-), relation in which the term AO is a term of amplitude equal to AO = ei ), HS1, a phase compensation term e] t having been introduced on one of the reception signals

  radio signal e2 for example.

  The amplitude of the sum of the aforementioned signals, under these conditions, is written according to the relation (7): A = [el + e2 euI = A01sing + cospcos4 -jkcos9sin $ I

= AO '1+ (k2-1) cos2p + k sin2p cosO.

  It is thus found that the sum of the amplitude of the reception radio signals compensated by a phase term, has the term of amplitude A0 and a directivity term D (p, k) satisfying the relation (8):

D (g, k) = (k2-1) cos2p + k sin2p cos.

  Of course, according to a particularly advantageous aspect of the antenna system, object of the present invention, the term of said directivity can be made independent of P that is to say the orientation angle of the

  antenna system with respect to the direction of polarisa-

of the incident carrier wave.

  In a first embodiment, it is indicated that the directivity term can be made independent of the orientation angle p by taking for example two particular values for the parameters 4 and respectively k, these

  values being equal for example to n - / 2 and k - 1.

  Under these conditions, as shown in FIG. B, the coupling circuit 3 may comprise a circuit 30 of

  relative phase shift of the first and second radio

  receiving circuit el, e2 of a given phase shift value, this circuit 30 making it possible to generate a first el and a second e2 phase-shifted reception signal. Of course, in the above notation, it is understood that * denotes the relative phase shift introduced between the first el and the second e2 radio reception signal. In addition, the coupling circuit 3 comprises a summing circuit 31 of the first and second phase-shifted reception signal ele, e24, this summing circuit making it possible to generate the resulting reception signal er, which of course verifies the

  relation (6) previously mentioned.

  In the case of the first embodiment in which one chooses for example * = n / 2 and k = 1, the phase shifter circuit 30, as represented in FIG. 6a, can be a phase-shifting circuit introducing a fixed phase shift value * = n / 2. The phase shifter circuit 30 can then be

  introduced to receive the second radio signal

  reception frame e2 to generate the second phase-shifted radio reception signal e2 * of the aforementioned value = 90. Under these conditions, it is indicated that the resulting reception radio signal er is a

  signal corresponding to a transmission antenna system-

  reception, the radiation pattern of which is substantially circular in the third plane A previously described in

the description.

  For a value 4 = 40 and in this first embodiment, it is indicated that the radiation pattern for the corresponding antenna system is substantially ovoid in the third plane A. According to a second embodiment such that

  shown in Figure 6b, it is indicated that the term

  D (p, k) can also be rendered independent of the angle

  orientation of the antenna system in relation to the

  polarization of the incident wave in the case where the expression below is satisfied (relation 8):

(k2-l) cos2p + k sin2p cos = 0.

  Under these conditions, the remarkable value of the phase shift term * introduced satisfies the relation (9):

= Arc cos 1-k2 1e2.

  2k2 1 ell Indeed, it is indicated that, given the structure of the antenna system and the relative position of the first and second antenna 1,2, the ratio of the first and the second radio reception signal el, e2, as well as the ratio of their amplitude I ell, I e2J satisfies the relation (10): el = tbA e2 k Given these elements, as represented in

  FIG. 6b, the relative phase-shift circuit 30 may advantageously

  It can be formed by a controlled phase shifter circuit 30a receiving on a relative phase shift control input a phase shift control signal, denoted c +, proportional to the ratio of the amplitude of the second and the first radio reception signal. The signal ci can be produced from an analog type circuit, or from a transcoding circuit of value 30b, which, from the signals

  radio reception el and e2, after amplification

  tion, delivers the phase shift control signal

  for example the ratio of the amplitude of the second and

  of the first reception radio signal el, e2.

  In a simplified embodiment, it is indicated that for a remarkable value of k, k = 1/13, the previously mentioned relation (9) is simplified, the correction phase term making it possible to compensate the directivity as a function of the angle. P the orientation of the antenna system with respect to the direction of polarization of the incident wave satisfying the relationship: cosO - le21l I ell The embodiment as shown in Figure 6b and allows to enslave the relative phase shift between the first el and the second reception signal e2 to the value of the orientation angle of the antenna system with respect to the polarization direction of the incident wave and thus generating a resultant reception signal whose diagram circular reception in the third plane

  A is independent of this orientation angle and geometry.

  relative trie of the first and second antennas.

  In a particularly advantageous manner, it is indicated that the antenna system, object of the present invention, can be used whatever the orientation

  of the antenna system in relation to the polari-

  This is because the amplitude term can be maximized and independent of the directivity term for a maximum antenna gain, i.e., for a maximum receive amplitude. Under these conditions, the transmitting-receiving antenna system, which is the subject of the present invention, can, if necessary, be used in

  circular polarization of the incident carrier wave.

  FIGS. 7a and 7b show the radiation patterns obtained by the implementation of the transmit / receive antenna system, object of the present invention, in the case where, for FIG. 7a, the term of phase shift 4 = 40 and, for Figure 7b, in the

  case where the phase shift term 4 = 90.

  Finally, it is indicated that the phase-shifter circuits 30 or 30a can be produced by commercial phase shifter circuits marketed under the reference PSCQ 2-120 by the company MINICIRCUIT in France. These phase shifters are

  passive circuit phase shifters with a reversal

  ble, that is, two-way transmission. In

  consequence, the realization of a reversing summing circuit

  for example, for the constitution of the summing circuit 31, it is of course possible to use the omnidirectional antenna system both for transmission and reception, which makes it possible to envisage applications

very varied.

  An omni-directional transmitting / receiving antenna system with a substantially circular, particularly high-performance, circular pattern has thus been described. In

  particular, in the case of use in a

  For example, it allows for an omnidirectional reception of messages transmitted by systems such as the system.

R.D.S. for example.

Claims (7)

  1. Omnidirectional transceiver antenna system   * rectionnelle angular diversity and polarization, characterized in that it comprises: - a first unidirectional radio antenna in a first direction, defined by two orthogonal planes, forming principal planes of this antenna, one of these plans defining a foreground (C),   - a second unidirectional radio antenna   in a second direction, defined by two orthogonal planes, forming principal planes of this antenna, one of these planes defining a second plane (B), the first and the second antenna being placed so that the first and the second plane being orthogonal, the first and second antennas are orthogonal, which   makes it possible to obtain, for said antenna system, a dia-   gram of substantially omnidirectional radiation formed by a bidirectional radiation pattern in a third plane (A), orthogonal to the first and second   plan and formed by a main plane of the first, respec-   second antenna, and by a radiation diagram.   unidirectional in the first (C), respectively the   second (B) plane, the first and second radio   each delivering a first and second respectively e2 radio reception signal; means for combining in amplitude and / or in phase said first and second reception radio signals making it possible to generate a resultant reception signal whose radiation pattern, corresponding to the transmission-reception antenna system, is substantially   circular in said third plane (A).   Antenna system according to claim 1, characterized in that the first antenna is a metal frame antenna and the second antenna is a ferrite core frame antenna, the ferrite core antenna being placed in the vicinity of the antenna. one side of the frame the metal frame antenna.   3. System according to one of the preceding claims   characterized in that said amplitude and / or phase combination means of said first and second radio reception signal comprise at least: - relative phase shift means of the first and second radio signal for receiving a phase shift value determined, to generate a first and a second phase-shifted reception signal, - summing means of the first and second phase-shifted reception signal for generating said resulting reception signal.   4. System according to claim 3, characterized in that said relative phase shift means are formed by   a phase-shifting circuit receiving said second radio signal   receiving electrical signal, to generate a second phase-shifted radio reception signal with a value of phase shift 4 determined.   5. System according to claim 4, characterized in that, for a phase shift value = = 90, said resultant reception signal has a radiation pattern.   circular in said third plane.   6. System according to claim 4, characterized in that, for a phase shift value = = 40, said resultant reception signal has a radiation pattern.   substantially ovoid in said third plane.   7. System according to claim 3, characterized in that said relative phase shift means are formed by a controlled phase shifter receiving on a relative phase shift control input a signal proportional to the ratio of the amplitude of the second and the first radio frequency signal. reception, to enslave the relative phase shift between the first and second reception signal with the value of the orientation angle of the antenna system with respect to the polarization direction of an incident wave and to generate a resulting reception signal including the circular reception pattern in the   third plane (A) is independent of this angle of orientation. tion.