EP0824766A1 - Unite d'antenne - Google Patents

Unite d'antenne

Info

Publication number
EP0824766A1
EP0824766A1 EP96914272A EP96914272A EP0824766A1 EP 0824766 A1 EP0824766 A1 EP 0824766A1 EP 96914272 A EP96914272 A EP 96914272A EP 96914272 A EP96914272 A EP 96914272A EP 0824766 A1 EP0824766 A1 EP 0824766A1
Authority
EP
European Patent Office
Prior art keywords
radiator
antenna unit
antenna
slot
unit according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP96914272A
Other languages
German (de)
English (en)
Inventor
Andrew Douglas Pearson Green
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DILWORTH, IAN JOHN
Original Assignee
CENTREPOINT TECHNOLOGY Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CENTREPOINT TECHNOLOGY Ltd filed Critical CENTREPOINT TECHNOLOGY Ltd
Publication of EP0824766A1 publication Critical patent/EP0824766A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/28—Combinations of substantially independent non-interacting antenna units or systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/32—Adaptation for use in or on road or rail vehicles
    • H01Q1/325—Adaptation for use in or on road or rail vehicles characterised by the location of the antenna on the vehicle
    • H01Q1/3275—Adaptation for use in or on road or rail vehicles characterised by the location of the antenna on the vehicle mounted on a horizontal surface of the vehicle, e.g. on roof, hood, trunk

Definitions

  • the present invention relates to an antenna unit, and in particular to a low profile antenna unit which provides dual band operation for reception and/or transmission for both terrestrial and earth-orbiting satellite radio communication.
  • Radio transmitters and receivers, or communication units, for terrestrial radio communication are commonly used in many applications such as mobile telephones in motor vehicles, ship-to-shore communications, and hand-portable personal pagers. In some applications the transmitter and/or receiver is fixed, and in others mobile.
  • These communications systems commonly operate in the 400 MHz, 900 MHz and 1.7 GHz parts of the radio spectrum, and use antenna units which are usually vertically oriented and are usually multiples of one-quarter wavelength ( ⁇ 0 /4) long, where ⁇ 0 is the free-space wavelength of the signal.
  • These vertical rod ⁇ 0 /4 antennas with a ⁇ 0 /4 image provided by a ground plane, efficiently receive and transmit with a substantially omnidirectional antenna response pattern in the azimuthal plane to a signal with a vertically oriented electric field.
  • the term "vertically oriented electric field” as used herein means an E-field either polarised or with substantial components transverse to the azimuthal plane.
  • Such an antenna unit is well-suited to applications such as mobile cellular radio communication, but is exposed and may be prone to damage, for example if mounted on a motor vehicle.
  • a slot antenna for use on a motor vehicle, and with a much lower profile, is disclosed in the document GB 1387679, which describes an antenna, which operates in a mode referred to herein as a "slot" mode.
  • This antenna is a planar slot-ring of conducting material on a substrate mounted above and parallel to a ground plane, the "slot” being formed by the air gap between the slot-ring and the ground plane.
  • Such a slot antenna when mounted horizontally, has an antenna response pattern similar to that of a vertical ⁇ 0 /4 antenna for a vertically polarised radio signal, but the frequency response is too narrow to be useful in many applications.
  • a slot antenna with a single slot-ring will have a frequency response with a bandwidth of about 3%. At 500 MHz, this would give a useful bandwidth from 493 MHz to 507 MHz, which is too narrow for many applications, such as cellular radio communication.
  • the document GB 1387679 recognises this problem, and proposes the use of a second parallel slot-ring with a different diameter. Since the diameter of the slot-ring is one parameter that defines the resonant frequency, this document suggests that two parallel slot-rings may be used to communicate at two different frequencies, each frequency being that for a slot-ring on its own. Because the frequencies of the slot-rings are far enough apart, the slot-rings do not interact strongly and are essentially uncoupled. This antenna arrangement of two slot radiators provides radio communication at two discrete frequencies, each having a narrow bandwidth.
  • Radio transmitters and receivers, or communication units, for satellite communication are becoming increasingly common.
  • the global positioning system GPS
  • Such satellite systems typically operate at frequencies around 1.5 GHz.
  • the antennas for these systems have an antenna response pattern which is usually omnidirectional in the azimuthal plane and omnidirectional ideally over a half-sphere centered about the zenith.
  • a patch antenna has a conducting strip or patch, and is usually rectangular in outline with a length of each side L of about ⁇ 0 /2.
  • the patch radiator is mounted above and parallel to, or slightly inclined to a ground plane.
  • Other designs use a C-shaped patch, or even an elliptical patch.
  • a basic description of rectangular patch antennas may be found in a book titled "Antennas" by John D. Kraus, published by McGraw-Hill Book Company, 1988, at pp 745-749.
  • radiators suitable for communication with satellites may be found in a book entitled "VHF and UHF Antennas” by R. A. Burberry, ISBN 0 86341269 6, in particular a “slot dipole antenna” described on page 228 and a “crossed slot with backing cavity” on page 225.
  • This antenna unit has a generally horizontal planar microstrip or patch radiator for satellite communication, surrounded in the same plane by a loop radiator and with a rod radiator extending perpendicularly through the patch radiator. All three radiators share a common ground plane.
  • the loop radiator is broken at a point, and so has a different mode of operation from the slot antenna described above.
  • the loop radiator is horizontally polarised and is therefore not well-adapted for efficient reception of generally vertically polarised signals,- hence the need for the rod radiator.
  • the loop is also a poor radiator in the configuration shown, that is, near the ground plane, and is therefore not well-adapted for transmission.
  • an antenna for combined satellite and terrestrial radio communication has not been made into a compact, low profile and efficient antenna unit.
  • the present invention provides an antenna unit for radio communication with terrestrial and satellite communication units, the antenna unit comprising substantially planar conducting sections in close proximity, the sections defining: a) at least one ground plane; b) a first radiator with a first antenna response pattern, the first antenna response pattern extending substantially in an elevation plane for communication with a satellite communication unit; and c) a second radiator with a second antenna response pattern for communication with a terrestrial communication unit, characterised in that the second antenna response pattern is adapted for radio communication with electromagnetic radiation having a vertically oriented electric field, the second antenna response pattern extending substantially in an azimuthal plane.
  • a terrestrial communication unit may be any radio transmitter and/or receiver on earth, and similarly a satellite communication unit may be any radio transmitter and/or receiver in space.
  • radio means a part of an antenna which may receive and/or transmit radio signals.
  • the antenna response pattern is defined in a half-sphere centered on the antenna unit, so that the azimuthal and elevation planes pass through the antenna unit.
  • the antenna response pattern may then be defined across 360° in the azimuthal plane and across 180° degrees in any elevation plane passing through the antenna unit.
  • the antenna unit may advantageously have a second antenna response pattern that is omnidirectional over most of the azimuthal plane, and is ideally omnidirectional over substantially the whole of the azimuthal plane.
  • the antenna unit may also advantageously have a first antenna response pattern that is omnidirectional over most of the elevation plane, and is ideally omnidirectional over substantially the whole of any such elevation plane so that the first antenna response extends across a half- sphere centered on the zenith.
  • the term omnidirectional when applied to an antenna ideally means an antenna with an antenna response pattern which is substantially equal in all directions.
  • the actual performance of an antenna unit may deviate from this ideal equal antenna response pattern.
  • a finite or non-symmetrical ground plane may produce some ripple in the far field radiation pattern.
  • the antenna pattern response is said to be omnidirectional to within a certain number of decibels.
  • Communication systems are generally designed to accommodate any variations from an ideal omnidirectional antenna response pattern, and the term omnidirectional as used herein includes such non-ideal cases.
  • the first antenna pattern response is omnidirectional to within 6 dB.
  • the second antenna pattern response is omnidirectional to within 6 dB.
  • the first radiator is a patch radiator operating in a patch mode
  • the second radiator is a slot radiator operating in a slot mode
  • the first radiator is a patch radiator operating in a patch mode
  • the second radiator is a bent folded monopole radiator operating in a folded monopole mode.
  • the antenna unit will for most applications need to respond to a range of frequencies within a frequency band, which for terrestrial signals may, for example, be one of the mobile radio bands at about 400 MHz, 900 MHz and 1.7 GHz. Therefore, it is advantageous if the second radiator of the antenna unit has an intrinsically broad operating bandwidth, for example a bent folded monopole may have at least a 20% bandwidth relative to a central operating frequency. If the second radiator operates in a slot mode, it may be formed from a number of sections that are designed to broaden the frequency response of the slot mode.
  • the second radiator may be arranged to be substantially coplanar with the first radiator.
  • the second radiator is arranged in the shape of a closed ring.
  • the ring is a closed annulus and operates in a slot mode.
  • a single section of the second radiator in the shape of a ring and operating in a slot mode will have a relatively narrow bandwidth of operation of about 3%, which equates to a bandwidth of ⁇ 15 MHz at 1 GHz.
  • mobile radio bands typically extend over 3 to 5 times this bandwidth. Therefore it is advantageous if the frequency response of the second radiator is broadened. This may conveniently be achieved by forming the second radiator antenna from a number of sections. For example, each section on its own may have an operating frequency separated by about 3% from another section. Such sections when placed in close proximity will have a response which overlaps and couples to broaden the response of the second radiator operating in a slot mode.
  • e R 2
  • Increasing the number of layers of parallel annuli will increase the broadening. The exact amount of broadening depends on a number of parameters, such as the sizes, shapes and relative lateral separations and spacing of the sections with respect to each other and to the ground plane, the dielectric constants of the spacing layers, and whether and at what points the sections are electrically connected together. If the sections are electrically insulated from one another they will still interact by parasitic coupling.
  • Parasitically coupled slot-rings provide the advantage of close control of matching of parameters and coupling.
  • planar sections of conducting material may be printed on thin dielectric substrates and sandwiched together in a solid multilayer construction, with each section thereby held in secure relationship with and, if desired, electrically insulated from one another.
  • these slot-rings may be concentric and coplanar annuli with different radii printed on one side of a single circuit board and centered about the same point.
  • the sections may be electrically connected together at points.
  • the slot-rings may be annuli with different circumferences, and centered at different points so that the outer edge of each annulus comes together and is electrically connected to the others at one point.
  • the ratio of the conductor width W of a slot-ring to the height H of that slot-ring above the ground plane governs the impedance of that slot- ring, and the /H ratio may therefore be chosen such that each section provides equivalent electrical performance in terms of resonance characteristics.
  • the patch radiator may be inside the slot-ring.
  • the feasibility of this arrangement depends on a number of factors which determine the sizes of the slot slot-ring and the diagonal extent of the patch, but in general this is possible when the frequency bands used by the patch radiator are at least as high as those used by the slot radiator.
  • the patch radiator may also be substantially coplanar with. the slot radiator, or at least not extend significantly above the plane defined by the slot radiator. Then, when the patch radiator is inside the ring of the slot-ring radiator, the lateral extent and vertical thickness of the antenna unit are minimised making it easier to mount the antenna unit flush with the surface of a mobile unit such as a motor vehicle, or within a compact hand-held device such as a mobile telephone or personal pager.
  • the first and second radiators may also advantageously share a common ground plane.
  • the ground plane may optimally be arranged to be parallel and adjacent to both radiators. The greater the lateral extent of the ground plane, the greater the efficiency of the antenna unit, and hence the ground plane may also optimally extend beyond the edges of the radiators.
  • the ground plane extends no farther than the outer edges of the antenna unit, which may be the case where the permissible size of the antenna unit is limited, for example, in the case of a hand-held device.
  • the ground plane for the slot radiator may be in the shape of a ring which may match the shape of the slot-ring. Some of the volume inside the inner diameter of the slot-rings may then be made available for other uses in the device package, although the efficiency of the slot radiator will be lower as a result.
  • the patch radiator may serve as a ground plane for the slot radiator, with the patch radiator having its own ground plane.
  • both the patch radiator and its ground plane may interact with the slot radiator, with both the patch and its ground plane serving to some degree as ground planes for the slot radiator.
  • the extent of the bent folded monopole radiator transverse to the ground plane may be reduced if the folded monopole is bent to parallel the ground plane.
  • the folded monopole will generally have an elongate loop, and this loop may be folded to run in a plane which is either transverse or parallel to the ground plane.
  • bent folded monopole will be in close proximity but in general be laterally spaced from the patch radiator.
  • the first and second radiators do interact to some degree when placed in close proximity, and the antenna resonances of the different radiators of the antenna unit have to be optimised as a whole, but the antenna far field response patterns remain independent, making it possible here to combine different antenna radiators in a compact and low profile arrangement.
  • close proximity generally means a proximity resulting from an attempt to reduce or minimise the physical size of the antenna unit. Such a close proximity between the sections will generally cause an interaction between the sections, such as frequency response broadening or frequency response shifting.
  • first and second radiators are electrically connected to each other. This allows just one radio frequency feeder to be run to the antenna unit. In this case the first and second radiators must be designed to be impedance matched to each other to minimise standing waves and maximise power transfer.
  • the first and second radiators may not be directly connected to the patch radiator, and each may have its own transmission line.
  • the transmission lines may still be joined at a point and provided with, for example, quarter-wave stubs to prevent significant levels of transmission signals destined for one radiator from reaching the other radiator.
  • the antenna unit is mounted in a housing to provide protection.
  • the housing will then comprise a cover section which is substantially transparent at the frequencies used by the antenna unit for radio communication.
  • the cover may be formed from a suitable plastics material such as ABS, and may additionally be coloured to provide a good cosmetic match with any surrounding surfaces. Any frequency shift resulting from the cover dielectric may be taken into account at the antenna design stage.
  • the antenna unit according to the invention may be used on a mobile unit. Therefore, the invention also provides a mobile unit comprising an antenna unit for radio communication with terrestrial and satellite communication units, in which the antenna unit is according to the invention as described above.
  • a mobile units include a motor vehicle, a motor boat or an aircraft, and also a hand-held personal telephone or pager.
  • An antenna unit may advantageously be mounted so that its housing or cover is substantially flush with the surrounding surface of the mobile unit.
  • a motor vehicle body shell may have a recess or aperture provided in a roof panel, or hood or trunk lid, which receives the antenna unit housing.
  • the antenna unit may stand proud of the surface.
  • the mobile unit may be a motor vehicle with a steel body shell.
  • a body shell normally comprises a roof section which is substantially horizontal and at the highest point of the vehicle.
  • the antenna unit may then conveniently be mounted on the roof section, which may be provided with a recess so that the antenna unit can be mounted flush, and use the conducting skin of the motor vehicle as a ground plane.
  • Figure 1 is a top view of a first antenna unit according to the invention, showing a slot radiator with two annular slot-rings, and a patch radiator centered within the slot radiator, and with both antenna radiators having the same ground plane;
  • Figure 2 is a side view in cross section taken along line II-II of the first antenna unit of Figure 1;
  • Figure 3 is a top view of a second antenna unit according to the invention, showing a slot radiator in the form of a wire suspended above a patch radiator and using the patch radiator as a partial ground plane, and with a main ground plane for both the patch and slot radiators,-
  • Figure 4 is a side view in cross section taken along line IV-IV of the second antenna of Figure 3,-
  • Figure 5 is a top view of a third antenna unit according to the invention, showing a slot radiator in the form of one annulus and a patch radiator above the slot radiator, and with both radiators having a common feed point and ground plane,-
  • Figure 6 is a side view in cross section taken along line VI-VI of the third antenna unit as shown in Figure 5.
  • Figure 7 is a side view of a known folded monopole radiator
  • Figure 8 is an isometric view of a fourth antenna unit according to the invention, showing a first bent folded monopole radiator and a patch radiator beside the monopole, with both radiators having separate feed points and a common ground plane,-
  • Figure 9 is a side view of the first bent folded monopole of Figure 8, taken along line IX-IX;
  • Figure 10 is an isometric view of a fifth antenna unit according to the invention, showing a second bent folded monopole radiator and a patch radiator beside the monopole, with both radiators having separate feed points and a common ground plane.
  • the drawings show orthogonal axes x,y and z.
  • Axes x and y are in the azimuthal plane, and the elevation plane is any plane parallel to the z axis, which defines vertical.
  • the azimuthal plane will normally be parallel with the horizon. If the antenna unit is used in space the azimuthal plane may have any orientation according to the application of the antenna unit.
  • the first antenna unit 1 consists of a slot radiator 2 and a square patch radiator 3. Both radiators share a common horizontal ground plane 4, which extends beyond the edges of the slot radiator 2 so increasing the efficiency of the slot mode.
  • the slot radiator 2 is formed from two parallel annular conducting slot-rings, namely an upper slot-ring 5 and a lower slot-ring 6, on opposite sides of a printed circuit board 7 which is on the top side of the antenna unit 1.
  • the patch radiator 3 is formed from conducting material on the upper side of the circuit board 7.
  • the ground plane 4 is formed from a conducting layer on the lower surface of a lower printed circuit board 8 which is on the bottom side of the antenna unit 1.
  • the upper and lower circuit boards are spaced apart and held in a solid construction by dielectric layers, with one layer 9 between the slot radiator 2 and ground plane 4, and the other layer 10 between the patch radiator 3 and the ground plane 4.
  • the two slot-rings 5,6 of the slot radiator are electrically connected together by a VIA at a ground point 11 and from this point connected perpendicularly through the slot dielectric 9 to the ground plane 4.
  • the slot-rings also have a common slot feed point 12, which is in this example spaced optimally at a circumference of about 5° of free-space wavelength from the ground point 11.
  • the patch radiator 3 has a patch feed point 13 which is midway between two parallel edges and one-third the way in from another edge.
  • Each feed point 12,13 is wired to a core conductor 14,15 of a shielded coaxial cable 16,17.
  • Each conductor passes through a bore 18,19 which forms a channel from the slot or patch radiator through the dielectric layer 9,10, lower circuit board 8 and ground plane 4.
  • the shielding 20,21 of each cable is grounded to the ground plane next to each bore so as to be nearly directly below the feed point 12 , 13 .
  • the two coaxial cables 16,17 may be joined into a single cable, and isolation between the signals may be achieved in a conventional manner by the use of quarter wave stubs and/or by PIN diode protection.
  • the antenna unit comprises a tuning capacitor 22 at a point on the slot-ring directly opposite the ground point 11.
  • the exact location of the capacitor on the ring has a bearing on the sensitivity of the resonant frequency of the ring to the value of capacitance. If the connection of the capacitance is offset from the directly opposite ground post position, then less frequency change is induced for a given capacitance. This is a useful feature in a manufactured item.
  • This capacitor can take one of several forms, and as shown in Figures 1 and 2 is a rectangular conducting section on the upper circuit board 7 connected by a narrow neck 23 to the outer edge of the upper slot-ring 5.
  • the area of the capacitor is trimmed along an edge, for example by a laser, and as indicated by a dashed line 24 in order to tune the resonant frequency of the slot-ring 5 to the desired value.
  • variable capacitor is a grounded conducting plate between the slot radiator and the ground plane that can be moved to adjust the separation between the plate and slot radiator.
  • a further way of varying the capacitance between these layers would be to insert or withdraw a section of dielectric called a dielectric puck.
  • the capacitance can also be changed by means of electronic switching, that is, by turning on or off PIN diodes connected to capacitor sections.
  • This method of changing the resonance frequency and/or the matching is applicable on transmit and receive.
  • For low power transmit and for receive it is also possible to tune the resonance of the antenna by means of the capacitance provided by varying the bias voltage applied to reverse biased capacitance diodes.
  • the slot-rings 5,6 of the slot radiator 2 typically have a circumference of up to , where ⁇ 0 is the free-space wavelength of the radio wave.
  • the impedance of the slot radiator depends on a number of factors such as the width of the conductors forming the rings or slot-rings and their heights above the ground plane 4, taking into account also any dielectric 9,10 between the slot-ring and the ground plane.
  • the circumference of each slot-ring is about 163° of free-space wavelength. At 1 GHz, the circumference is then 136 mm (diameter 43.2 mm).
  • the spacing of the slot-ring above the ground plane would optimally be about 8°, which at 1 GHz is 6.7 mm.
  • the spacing would be about 2.5°, or 2.1 mm.
  • the width W of the patch is the dimension between the two edges within which the feed point is centered, and the length L is the dimension at right angles to this.
  • the width W of the patch may be conveniently be chosen to be about the same as, or just less than, the length .
  • the size of a square patch is therefore 47.4 mm along a side, and 67.1 mm diagonally. This is somewhat larger than the 43.2 mm diameter of the 163° circumference slot- ring described above at the same frequency.
  • the square patch would have a diagonal dimension of 39.5 mm, and could then fit within the 1 GHz slot-ring.
  • the optimum spacing of the slot and patch radiators 2,3 can also be adjusted by selecting appropriate dielectric layers 9,10. This permits the slot and patch radiators to be formed on the same circuit board substrate 7.
  • a patch radiator 3 as described has a radiation pattern which is broad and directional, typically at least X A of the full solid angle, or ⁇ sr.
  • this radiation pattern is a cone approaching a half-sphere centered on the zenith.
  • the frequency response of the patch radiator 3 may be broadened, for example by inclining the patch with respect to the ground plane.
  • the effect on the slot radiator 2 of the two parallel and electrically connected slot-rings 5,6 is to broaden the frequency response of the slot radiator by a factor of about 1.5 to 2. More parallel slot-rings may be added to broaden further the frequency response.
  • the slot-rings may conveniently be formed on the surfaces of circuit boards in a multilayer laminated construction. The inner and outer diameters and widths of the slot-rings will not be the same, but will generally decrease for each lower slot-ring in the construction.
  • the resonant frequency for each slot-ring on its own is chosen to be within 3% of another slot-ring, so that each slot-ring in the multilayer slot-ring structure is resonantly coupled to broaden the frequency response of the slot radiator as a whole.
  • FIGS 3 and 4 show a second antenna unit 31 which consists of a slot radiator 32 in the form of a single circular slot-ring of wire, mounted above a square patch radiator 34.
  • the patch radiator is formed from a conducting layer on a printed circuit board 33 which is mounted on a dielectric spacer layer 36 above a ground plane 35 formed from sheet metal which extends beyond the outer edge of the patch radiator 34.
  • the slot radiator 32 uses the topmost conducting surface of the patch radiator 34 as a partial ground plane, with the ground plane 35 serving as a main ground plane for the slot radiator 32.
  • the patch radiator 34 has a similar construction to the patch radiator 3 described for Figures 1 and 2.
  • the slot radiator 32 is quite different, being formed from a ring of wire with circular cross section. This construction maintains a reasonable efficiency for the slot radiator 32, while allowing it to be placed above the patch radiator 34.
  • Such a wire slot radiator 32 would have a relatively narrow bandwidth, which could be broadened by the addition of other parallel and/or concentric rings of wire or printed conductor, suspended by low loss substrate.
  • the patch radiator 34 is fed by a shielded coaxial cable 41 with a core conductor from this cable electrically connected to the patch 34 at a patch feed point 40, in a like manner to the patch radiator 3 of Figures 1 and 2.
  • this cable 41 serves as a single unbalanced coaxial feed for both radiators of the antenna unit 31 as will be clear from the following description.
  • the slot-ring is suspended above the patch radiator 34 by an insulating post 38 and at the opposite side of the slot-ring by a conducting post 37 which extends through an aperture 43 in the patch radiator 34 to the ground plane 35.
  • the conducting post 37 provides a ground point on the slot-ring by electrically connecting the slot radiator to the ground plane 35 at that point, and the insulating post 38 may comprise one of the forms of capacitance adjustment described above.
  • the aperture 43 is made small compared with the wavelength of operation of both the patch and slot radiators, and so evanescent modes generated by the hole in the patch conductor are negligible, and therefore so will be the effect on the operation and radiation efficiency of the patch.
  • a wire 42 is electrically connected to the upper surface of the patch radiator 34 at the patch feed, point 40, and extends to the wire slot-ring of the patch radiator where it is electrically connected at the slot feed point 39.
  • a single feed line may therefore serve both radiators of the antenna unit 31.
  • the slot-ring 32 may be offset from the centre of the patch radiator 34 in order to place the slot feed point 39 directly above the patch feed point 40.
  • the parasitic capacitance introduced by the introduction of the patch above or below the slot-ring serves to alter the feed point on the slot-ring. Since the feed point of the slot-ring is designed to be fed by a low impedance TEM (transverse electric and magnetic) unbalanced transmission line with, for example, an impedance of 50 ⁇ , the effects of the capacitance introduced by the patch area above the ground plane is small and it is readily compensated for in the matching.
  • TEM transverse electric and magnetic
  • a Gamma matching section was used to feed and match the slot-ring.
  • Other feed and matching arrangements are equally applicable.
  • an H-field ring coupling to the slot-ring will work well.
  • an antenna unit 51 has an square patch radiator 52 mounted above an annular slot radiator 53.
  • the radiators 52,53 are made from conducting sections on either side of a printed circuit board 56.
  • the two radiators are not centered with respect to each other, but are aligned so that the feed points 54 of both radiators are immediately adjacent, with a short signal VIA 57 electrically connecting the feed points to each other.
  • the radiators will occupy more space, but this embodiment provides a more efficient electrical arrangement.
  • radiators When a common feed point is used, it will generally be desirable to use signal combining/decombining networks (not shown) so that both radiators may be used simultaneously.
  • PIN diode switches or relays may be used to switch between radiators.
  • the slot may comprise more than one slot-ring, as described above, in order to broaden the bandwidth of the slot mode.
  • additional slot-rings would be formed on additional surfaces of a multilayer circuit board, with all feed points adjacent and connected through by signal VIAs.
  • the feed point 54 on the patch 52 is offset in a manner different from previously described embodiments, with the feed point about one-third the way in from two adjacent edges.
  • the precise patch feed point in any particular application will depend on the resonant mode employed in the patch.
  • a dielectric layer 58 separates the patch and slot radiators from the ground plane 59.
  • the slot radiator 53 has a ground point 55, which is connected through to the ground plane by a ground VIA 60.
  • a single unbalanced coaxial feeder cable 61 has a core conductor 62 which passes through a bore 63 in the dielectric layer 58 to make electrical contact with the feed points 54.
  • the patch operation is largely unaffected by the slot- ring.
  • the slot-ring now has the capacitance produced by the patch connected across the feed point.
  • the position of the feed point is adjusted to conjugately match this capacitance in a manner familiar to those experienced in the art.
  • the slot radiator according to the invention may be used, and that is in a 3 ⁇ 0 /2 circumferential mode, which operates at three times the fundamental frequency.
  • a slot mode and a 3 ⁇ 0 /2 circumferential mode may be excited together and result in a far-field radiation pattern of mixed polarisation, that can be used for both terrestrial and satellite communication.
  • the slot radiator may act as both the first radiator (eg at 1575 MHz) and the second radiator (eg at 525 MHz) .
  • This higher frequency mode has a good return loss and more than 8% operating bandwidth when fed with the same feed arrangement as the fundamental slot mode.
  • the 3 ⁇ 0 /2 circumferential mode has a low feed impedance.
  • the radiation pattern of the 3 ⁇ 0 /2 circumferential mode has lobes in the azimuthal and elevation planes, with one of the azimuthal lobes centered on the feed point.
  • the radiation pattern is also broad in the elevation plane compared with the antenna response of the ⁇ 0 /2 slot mode of operation. Because the wavelength of the 3 ⁇ 0 /2 circumferential mode is one-third of the ⁇ 0 /2 slot mode, the W/H ratio is effectively one-third that of the /2 slot mode, and this has the effect of broadening the bandwidth of the frequency response.
  • the degree of azimuthal lobing does not have an effect greater than about 6 dB on the antenna response, and this sensitivity variation may be further reduced with a reduced extent ground plane and/or a shaped ground plane. Therefore, the radiation pattern characteristics of an antenna unit with a slot-ring operating at both fundamental and 3 ⁇ 0 /2 circumferential modes provides usable terrestrial and earth-orbiting satellite coverage, with the frequency for satellite communication three times that for terrestrial communication. In the case of such 3 ⁇ 0 /2 operation, the patch radiator may be omitted or included.
  • both the 3 ⁇ 0 /2 slot mode and the patch mode if they are resonant at the same frequency, will both contribute to the far field radiation response, and may together provide some useful diversity in terms of sensitivity to radio signals with different polarisations.
  • both sections operate essentially independently.
  • FIG 7 shows a folded monopole radiator 71.
  • the folded monopole radiator is in the shape of an elongate rectangular loop 70 extending transversely to a ground plane 72.
  • One end 73 of the loop passes through an aperture 74 in the ground plane to present an unbalanced feed point, which may be connected to an unbalanced coaxial feed cable as described above.
  • the other end 75 of the loop terminates at a solder joint 76 on the ground plane 72.
  • the typical length of a folded monopole radiator is between 0.25A and 0.375A .
  • the physical dimensions of the monopole loop can be reduced by a factor of l/(e ) a as described above, by embedding the monopole loop in a suitable low-loss dielectric material.
  • Whilst the folded monopole radiator 71 is an efficient antenna, it has the disadvantage of extending substantially away from the plane of the ground plane 72, even with a size reduction by choice of a suitable dielectric.
  • Figure 8 shows a fourth embodiment of an antenna unit 81, having a patch radiator 80, for example a patch radiator suitable for GPS communication at 1575 MHz, and beside this a first bent folded monopole radiator 82, both above a common ground plane 83.
  • the two radiators 80,82 are in close proximity such that their self-resonant frequencies may be lower than if either radiator were isolated from the other.
  • Typical dimensions of a typical first bent folded monopole 82 are shown in more detail in Figure 9.
  • the bent folded monopole 82 has a height above the ground plane which is- a function of the dielectric loading employed.
  • the first bent folded monopole 82 at one end extends through an aperture 86 in the ground plane 83 to an unbalanced feed point 84, and at the other end is soldered to the ground plane 83 at a ground point 85.
  • the bent folded monopole extends transversely to the ground plane by typically 0.06 ⁇ 0 , and then is bent at right angles to run parallel to the ground plane along an upper leg 87 for a distance of typically 0.142 ⁇ 0 , before being folded back underneath the upper leg 87, and finally through a lower leg 89 to the ground point 85.
  • the first bent folded monopole 82 is therefore folded in a plane transverse to the ground plane.
  • the far field radiation pattern of this radiator is remarkably similar to that of the conventional folded monopole described above, being substantially omnidirectional over the azimuthal plane, and with an electric field having substantial components transverse to the azimuthal plane.
  • the dimensions of the first bent folded monopole transverse and parallel to the ground plane can be reduced by a factor of up to l/(e R )*, as described above, by spacing the monopole loop from the ground plane with a suitable dielectric material or by embedding the monopole loop entirely or partially in such a dielectric.
  • the bent folded monopole has a broader frequency response, which may be advantageous in many applications needing a broader bandwidth of operation. Because of its bandwidth, the bent folded monopole is also less sensitive to proximity couplings from nearby objects, and is therefore less prone to detuning effects.
  • the impedance of the straight folded monopole is theoretically 200 ⁇
  • the impedance of the bent folded monopole is in general different from this.
  • the actual impedance will depend on the ratio of the dimensions of the sections parallel and transverse to the ground plane, and the height of upper leg 87 above the ground plane. These parameters may be selected to adjust and match the impedance. This height is called the electrical height which will be reduced if the space is filled with a dielectric material.
  • the dimensions used to fabricate the antenna have a secondary effect on the impedance, operating bandwidth and efficiency. From this it will be appreciated that many different variants of bent folded monopole may be used to effect the invention, and that the shapes selected do not need to be restricted to rectangular folded sections as illustrated.
  • the bent folded monopole 82 is positioned laterally adjacent the patch radiator 80, which is similar to those described above, with a feed point 88 spaced by a dielectric layer 90 parallel and above the ground plane 83.
  • FIG. 10 A fifth embodiment of an antenna unit 100 is illustrated in Figure 10.
  • a patch radiator 101 similar to that described above, is laterally adjacent to a second bent folded monopole 102 that is folded with two upper legs 107,109 in a plane parallel to a common ground plane 103.
  • the dimensions of the second bent folded monopole are similar to those of the first bent folded monopole, and can be reduced with the use of a dielectric.
  • the far field radiation pattern of this radiator is remarkably similar to that of the conventional straight folded monopole and first bent folded monopole described above.
  • the shape and dimensions of the ground plane may be used to modify the far field pattern.
  • bent folded monopoles described above have been illustrated for clarity as unsupported conductors. In practice, the monopoles could be supported either by a surrounding dielectric material or by printed circuit boards.
  • the bent folded monopoles of course, have conductors which extend transversely (these may, for example, be VIAs between or through circuit boards) to the ground plane and patch radiator, but are composed mainly of planar sections, that is sections of conductor arranged in planes parallel to the ground plane in order to minimise the height of the bent folded monopole radiators above the ground plane.
  • the feed points to the bent folded monopole and the patch radiators may also be electrically connected at a common feed point, with appropriate impedance matching, as described above for the slot and patch radiators.
  • the bent folded monopole may be placed closer to the patch radiator than illustrated, or folded over the patch radiator. This would, however, increase the degree of interaction between the two radiators, which would have to be compensated for in the design of the radiator sections.
  • the various embodiments of the antenna unit according to the invention may be optimised for a range of applications for the provision of dual band operation for reception and/or transmission for both terrestrial and earth- orbiting satellite radio communication.
  • the size of the antenna unit may be minimised, both in terms of lateral extent and vertical profile, allowing the antenna unit to be used with a variety of hand-held devices or mobile units, and the antenna response pattern may be designed to optimise radio communication with a range of satellite or terrestrial communication units.

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Waveguide Aerials (AREA)

Abstract

La présente invention concerne une unité d'antenne et, en particulier, une unité d'antenne à faible encombrement fonctionnant sur deux bandes pour la réception et/ou la transmission de communications radio tant terrestres que par satellite en orbite terrestre. Cette unité d'antenne (1, 31, 51, 81, 101) comporte les éléments suivants: des sections conductrices essentiellement planes, très proches l'une de l'autre, et définissant au moins un plan au sol (4, 34, 35, 59, 83, 103); un premier élément rayonnant (3, 34, 52, 80, 100) à un diagramme de réponse orienté selon un plan d'altitude pour les communications par satellite; enfin, un second élément rayonnant (2, 32, 53, 82, 102) à un diagramme de réponse orienté selon un plan azimutal pour les communications terrestres. Le second élément rayonnant est destiné à des communications radio par des signaux radio ayant un champ électrique polarisé sensiblement sur un plan d'altitude, tandis que les éléments rayonnants partagent de préférence un plan de sol commun. Dans un mode de réalisation, le premier et le second éléments rayonnants sont respectivement un élément rayonnant en forme de bande (3, 34, 52) et une fente rayonnante (2, 32, 53). Dans un autre mode de réalisation, les éléments rayonnants sont respectivement un élément rayonnant en forme de bande (80, 100) et un élément rayonnant unipôle coudé et replié (82, 102).
EP96914272A 1995-05-02 1996-05-01 Unite d'antenne Withdrawn EP0824766A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB9508891 1995-05-02
GBGB9508891.0A GB9508891D0 (en) 1995-05-02 1995-05-02 Antenna unit
PCT/GB1996/001041 WO1996035241A1 (fr) 1995-05-02 1996-05-01 Unite d'antenne

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EP0824766A1 true EP0824766A1 (fr) 1998-02-25

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EP (1) EP0824766A1 (fr)
AU (1) AU5768496A (fr)
GB (1) GB9508891D0 (fr)
WO (1) WO1996035241A1 (fr)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1301886B1 (it) * 1998-07-30 2000-07-07 Rac S R L Struttura di antenna multipla, in particolare per impianti satellitarie terrestri.
DE60044897D1 (de) * 2000-06-03 2010-10-14 Ipcom Gmbh & Co Kg Antennenanordnung für ein Mobiltelefon
DE10039772A1 (de) * 2000-08-16 2002-03-07 Bosch Gmbh Robert Kombinationsantenne
US6538605B2 (en) 2000-12-15 2003-03-25 Atheros Communications, Inc. Method and system for mounting a monopole antenna
WO2002049148A2 (fr) * 2000-12-15 2002-06-20 Atheros Communications, Inc. Procedes relatifs a la realisation d'une antenne unipolaire a tige laterale et d'une antenne unipolaire a tige centrale, procedes et systemes pour le montage d'une antenne unipolaire
US6883227B2 (en) 2000-12-15 2005-04-26 Atheros Communications, Inc. Method of manufacturing a side stem monopole antenna
US6718619B2 (en) 2000-12-15 2004-04-13 Atheros Communications, Inc. Method of manufacturing a central stem monopole antenna
DE20221946U1 (de) * 2002-03-07 2009-09-17 Kathrein-Werke Kg Kombi-Antennenanordnung zum Empfang terrestrischer sowie Satelliten-Signale
DE10229933A1 (de) * 2002-07-04 2004-01-29 Wilhelm Sihn Jr. Kg Antennenanordnung
JP2004343531A (ja) * 2003-05-16 2004-12-02 Alps Electric Co Ltd 複合アンテナ
JP4535007B2 (ja) * 2005-05-18 2010-09-01 株式会社デンソー 車載統合アンテナ装置の搭載構造
JP4071253B2 (ja) 2005-08-25 2008-04-02 東芝テック株式会社 複合アンテナ
US7605763B2 (en) 2005-09-15 2009-10-20 Dell Products L.P. Combination antenna with multiple feed points
EP3557694B1 (fr) * 2016-12-16 2022-09-28 Yokowo Co., Ltd Dispositif d'antenne
CN114284708B (zh) * 2021-12-17 2024-09-03 南京理工大学 基于Minkowski环状超材料分形超表面复合天线

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2870940B2 (ja) * 1990-03-01 1999-03-17 株式会社豊田中央研究所 車載アンテナ
US5402134A (en) * 1993-03-01 1995-03-28 R. A. Miller Industries, Inc. Flat plate antenna module
DE9414817U1 (de) * 1994-09-12 1994-11-03 Wilhelm Sihn jun. KG, 75223 Niefern-Öschelbronn Antenne für Kraftfahrzeuge
DE29506693U1 (de) * 1995-04-20 1995-06-29 Fuba Hans Kolbe & Co, 31134 Hildesheim Flachantennen-Anordnung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9635241A1 *

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WO1996035241A1 (fr) 1996-11-07
AU5768496A (en) 1996-11-21
GB9508891D0 (en) 1995-06-21

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