NZ522236A - A compact diversity (multiple directional) antenna to mitigate the effects of multi-path propagation - Google Patents

Abstract

An antenna (20) for telecommunication equipment includes one or more electromagnetically shielded sections (24a, 24b, 24c), each section includes a driven element (W) and one or more reflectors (22a, 22b, 22c), wherein the maximum dimension of the reflector perpendicular to the element is 0.2 ë, where ë is the antenna operating wavelength, wherein the antenna elements and sections are arranged for use as a diversity antenna and the shielded sections are formed from one or more reflector plates (22a, 22b, 22c),.

Description

NEW ZEALAND PATENTS ACT, 1953*- No: 522236 Date: 25 October 2002 INTELLECTUAL PROPERTY OFFICE OF N.Z 2 3 JAN 2004 RECEIVED COMPLETE SPECIFICATION IMPROVEMENTS RELATING TO ANTENNAE We, TAIT ELECTRONICS LIMITED, a New Zealand company, of 558 Wairakei Road, Burnside, Christchurch, New Zealand, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 128020-1 FIELD OF THE INVENTION The present invention relates to a compact antenna for telecommunications equipment.

BACKGROUND TO THE INVENTION The performance of many radio communication systems is limited by multi-path propagation. A common model for investigating the multi-path effect assumes that the base station is in reasonably clear area and that the terminal, for example a handheld or 10 mobile transceiver, is surrounded by a set of local signal scatterers, as shown in Figure 1. The effect of multi-path propagation is that a number of replicas of the wanted signal arrive at the receiving aerial at different times having travelled different distances from the transmitter. This causes an effect known as delay dispersion, which reduces the quality of reception. For example, it is what causes ghosting on a TV picture. In the 15 case of a digital communications link, if this delay dispersion is sufficiently small (less than about 25% of the symbol period) then it only has a minor impact on the ability to detect the correct symbol value. However, if the delay is large it causes what is known as Inter-Symbol-Interference (ISI).

As can be seen from Figure 1, for a given assumed maximum radius of the area of scatterers, the signals that get reflected from behind the receiver, for example path ADB, are substantially longer (-2r) than the direct path AB. Signals, for example path ACB, that arrive at angles within +/- 60 degrees of the direct path have path lengths < r greater than the direct path. This demonstrates that even reasonably wide beam width 25 antennas provide a worthwhile reduction in the delay dispersion caused by multi-path propagation.

Spatial diversity is a technique commonly used in radio communications systems to mitigate the effects of multi-path propagation. This technique uses more than one 30 antenna at the transmitter and/or the receiver to provide multiple versions of the received signal, each with a different combination of multi-path components. These different versions of the signal can be combined and processed by various techniques to 102181-2 provide a better estimate of the transmitted signal than would be provided with a single antenna. For this technique to work well the different antennae need to receive (or transmit) via different combinations of the multi-path propagation. An effective way of achieving this is to use a number of directional antennae each pointing in a different 5 direction. Such directional antennae are separated by side plates with a typical wavelength of between 1 and 10 wavelengths.

A set of directional antennae may also be employed as a further extension of this diversity technique, where multiple antennae are used at both the transmitter and 10 receiver and the multiple paths are utilised to carry additional data thereby increasing the capacity and spectral efficiency of the communications link. This technique is known as Multiple Input Multiple Output (MIMO).

Directional antennae, including diversity antennae implementing redundancy, can 15 overcome some of the multi-path propagation issues. In this manner, only the signals arriving by one or some of the paths are received or used to reconstruct the transmitted message, the rest being discarded as they degrade the perceived reception. Such antennae can also be used to provide directional transmissions. However, conventional diversity or directional antennae are too large for convenient use with handheld or 20 mobile terminals.

SUMMARY OF INVENTION It is an object of the invention to provide a directional antenna for telecommunications 25 equipment that is smaller in size than a conventional antenna designed for the same purpose. The invention may be implemented with multiple directional portions to provide a compact diversity antenna.

An antenna for telecommunications equipment including one or more 30 electromagnetically shielded sections each section including a driven element and one or more reflectors, wherein the maximum dimension of the reflector perpendicular to the element is 0.2 X, where X is the antenna operating wavelength. 102181-2 The antenna may be used for transmitting and/or receiving. In one embodiment, the antenna has multiple sections and driven elements, which results in an arrangement that can be utilised as a diversity antenna.

Preferably, the overall antenna radius is 0.2X or less. Preferably, the overall antenna height is 0.5X or less.

Preferably, the reflectors are formed from one or more reflector plates. The plates may be square or rectangular in shape. Alternatively, the plates have rounded top corners, or 10 taper towards the top edge.

Preferably, the sections are segments of a circle. Each plate forms a boundary edge of a segment.

Preferably, the segments meet at a central axis, each segment having one or more boundary edges extending radially from the axis. Preferably, each boundary edge is formed from one reflector plate.

Preferably, the maximum width of each reflector plate forming a boundary is equal to 20 the radius of the antenna Preferably, each reflector plate has a maximum width in the range of 0.04A. to 0.2X, more preferably each reflector plate has a maximum width in the range 0.06X-0.08X, and most preferably a maximum width of approximately 0.07X.

Preferably, each reflector plate has a height of 0.5A, or less. More preferably, each reflector plate has a height in the range of 0.1X-0.5X, and more preferably in the range of 0.3X-0.4A,, and most preferably a height of approximately 0.35A.

Preferably, each driven element has a height of 0.3X or less. More preferably, each driven element has a height in the range of 0.1A--0.3X,, and more preferably in the range of 0.20A.-0.25X, and most preferably a height of approximately 0.23X. Preferably the 102181-2 o in •») <l) height of the driven elements is lower than the maximum height of the plates. Each driven element may take form of a monopole or dipole. The radiation pattern of a driven element may be controlled by modifying the mutual coupling between driven elements through selection of an appropriate feed point.

Preferably, the antenna has a circular base.

Preferably, each reflector plate extends substantially to the perimeter of the base. 10 Preferably, each driven element has a diameter of 0.015X or less, and in the range of Preferably the minimum distance between a driven element and the reflector plate(s) in a shielded section is less than 0.2a.

Preferably the distance between the central axis and the driven element is between 0.05A, and 0.08A,.

An antenna for telecommunications equipment including two or more electromagnetically shielded sections, each section including one or more driven elements and one or more reflectors, wherein the maximum dimension of the reflector perpendicular to the element(s) is 0.2X, where A, is the antenna operating wavelength.

BRIEF DESCRIPTION OF DRAWINGS Preferred embodiments of the invention will be described with reference to the following drawings, in which: Figure 1 shows multi-path propagation in a transmission from a base station to a receiver, Figure 2a shows a plan view of a diversity antenna according to the present invention, Figure 2b shown an elevation view of the diversity antenna of Figure 2a, Figure 2c shows a perspective view of the diversity antenna of Figure 2a, 102181-2 I) (I Figure 3 a and 3b show actual dimensions of a possible embodiment of the antenna shown in Figures 2a to 2c, Figures 4a to 4c show various monopole driven elements and feed arrangements that can be used in the antenna, Figure 5 shows a dipole driven element and feed arrangement that can be used in the antenna, Figures 6a to 6c show various alternative feed arrangements for dipole driven elements, Figure 7 shows a switching scheme for the antenna, Figures 8a and 8b show alternative panel configurations for the corner reflectors of the antenna, Figure 9 shows a possible encapsulated embodiment of the antenna, Figure 10 shows an elevation polar plot of a response of the antenna in Figure 3, Figure 11 shows a 3D polar plot of the response of the antenna in Figure 3, 15 Figures 12-14 show changes in the radiation pattern effected by modifying the mutual coupling between the driven elements of the antenna, and Figure 15 shows a mutual coupling scheme for the antenna.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings it will be appreciated that an antenna according to the invention could be constructed in various forms and implemented in a range of applications. The following embodiments and applications are given by way of example only. It should also be appreciated that the use of diversity antennae and 25 methods of processing their outputs to optimise reception are known by those skilled in the technology and therefore need not be described here. Diversity methods such as optimal combining, maximum ratio combining, and/or intelligent switch selection can be implemented with the antenna.

Figures 2a-2c show various views of a preferred embodiment of a compact antenna 20 according to the invention, for use in telecommunications equipment for transmission/reception of signals. The directional antenna of the preferred embodiment 102181-2 "iwrSVCSMVI is a diversity antenna that provides redundancy to provide improved apparent reception. This can be used in a range of applications including transmission diversity, space-time coding and MIMO systems. In general terms, the antenna 20 has multiple driven elements positioned in isolated sections (a set of co-located directional driven elements) 5 directed at different angles to pick up different combinations of multi-path signals based on their angle-of-arrival. Either the best of these signals is selected, or they are combined to form a better composite signal. Where there is a low correlation between the occurrence of signal impairment at each of the aerials then the probability of all signals being impaired at once is low. This diversity approach is particularly effective in 10 the presence of significant multi-path from local scatterers. The antenna 20 is significantly smaller than existing diversity antennae, making it suitable for use in a wider range of applications.

More particularly, the antenna 20 includes a circular base/ground plane 21 adapted for 15 mounting on a radio transceiver or the like. The base has a plurality of corner reflectors that provide electromagnetically isolated sections 24a-24c of the antenna. The reflectors are formed from small reflector panels 22a-22c that extend upwards from the base and intersect along one vertical edge at a vertical axis 25 through the centre of the base 21. The bottom edges 26a-26c of the reflector panels 22a-22c that intersect the 20 base (ie the dimension of the reflector panels perpendicular to the driven element W), extend radially from the centre of the base towards the perimeter of the base, to separate the base into the sections 24a-24c. In the embodiment shown in Figures 2a-2c three o reflector panels are spaced equally each pair forming a 120 segment. Therefore, the reflectors form the boundary edges of each section 24a-24c, with reflector panels 22a, 25 22b forming the reflector defining section 24a, reflector panels 22b, 22c forming the reflector defining section 24b, and reflector panels 22c, 22a forming the reflector defining section 24c. The dimension of the reflector panels perpendicular to the driven element W equals the radius R of the antenna.

The reflectors may be constructed as integrally formed reflector panels from, for example, a mould or extrusion process, or formed from individual reflector panels that are adjoined, by soldering, welding or the like. The reflectors may either be integrally 102181-2 ») formed with the base or constructed separately and adjoined with the base, by welding, soldering or other suitable means. The reflector panels 22a-22c forming the reflectors are copper or some other electromagnetically reflecting material, to at least partially electromagnetically isolate each section 24a-24c. It is not necessary for the dimension 5 of the reflector panels 22a-22c perpendicular to the driven element to extend all the way to the perimeter of the base 21. They can merely extend far enough to provide the required level of electromagnetic shielding between each segment 24a-24c. For example, the base 21 can be made with a radius R greater than the dimension of the reflector panels 22a-22c perpendicular to the driven element. Each reflector attenuates 10 the amount of multi-path signal energy entering its section from all but the desired direction in which the section points.

One or more driven receiving/transmission elements 23a-23c is placed in each section 24a-24c at a suitable position on the base. Positioning of the driven elements 23a-23c is 15 dependent upon, among other things, the required amount of isolation of the antenna from multi-path signals. Preferably, the driven element is placed at a desired radius from the centre axis 25 in a section, halfway along the arc formed at that radius between the reflector panels forming that section. Preferably, the height Hp of each corner reflector panel 22a-22c extends beyond the height Ha of the driven elements 23a-23c, to 20 increase electromagnetic isolation experienced by the driven elements 23a-23c. In this way, each driven element 23a-23c receives signals substantially only from directions o corresponding to the 120 opening of the segment 24a-24c in which the driven element is positioned. Signals arriving from other directions are attenuated significantly by the reflector panels 22a-22c forming the corner reflectors. In one possible implementation 25 of the diversity antenna, only a subset of the antennae is selected for reception/transmission of signals by way of a selection switch. For example, one driven element may be selected which is used for transmission and reception. Transmission signals will be coupled to this driven element only, and only signals picked up by this driven element are used for reception. The driven element can be reselected as required. 30 Alternatively, diversity combining can be implemented with the antenna. 102181-2 It will be appreciated that any suitable number of corner reflectors and driven elements can be utilised in the antenna 20, to produce the required number of isolated segments, depending upon the level of redundancy required in the diversity scheme. For example, the antenna 20 may comprise two "corner" reflectors, each forming a segment of 180°.

This could be formed from one reflector panel extending across the diameter of the antenna 20, or two separate reflector panels meeting at a central axis. Alternatively, more than three segments could be provided, or just one segment to provide a standard directional antenna with no diversity capability.

The maximum dimension of each reflector panel 22a-22c perpendicular to the driven element W (that is, radius R of the antenna) forming a boundary is preferably 0.2A. or less, where X is the wavelength of the signal of the particular frequency band for which the antenna is used. Dimensions of reflector panels perpendicular to driven elements W in the range of 0.04A, to 0.2X have been found to work suitably. More preferably, the dimension of the reflector panel perpendicular to the driven element W is 0.06X-0.08A,, and most preferably, approximately 0.07/L Preferably, the edge of each corner reflector panel 22a-22c extends to the perimeter of the base 21, and therefore the diameter D of the base 21 is twice the dimension of a dimension of the reflector panel perpendicular to the driven element W. However, as previously mentioned, the base 21 may be bigger, or smaller than this and therefore could be in the range of 0.1X-0.2X or even more. The height Hp of each reflector panel 22a-22c is preferably 0.5X or less. Heights in the range of 0.1X-0.5X have been found to work suitably. More preferably, the height is in the range of 0.3M).4X.

Each driven element 23a-23c has a height Ha preferably 0.3A or less. Heights in the range of 0.1A,-0.3X have been found to work suitably. More preferably, the height of each driven element is in the range of 0.20X-0.25X, and preferably lower than the height Hp of the reflector panels 22a-22c. Each driven element preferably has a diameter of 0.015X or less. Diameters in the range of 0.014X-0.015X have been found to work 30 suitably. Preferably, each driven element is placed at a distance (radius) less than 0.08A, 102181-2 from the centre 25 of the base 21. Distances in the range of 0.05A, to 0.08X have been found to work suitably.

As illustrated in Figures 3a and 3b, these antenna 20 dimensions are significantly 5 smaller than current diversity antenna dimensions, which are based on conventional engineering design techniques. For example, for an antenna for use at 2.45GHz, typically the overall diameter D would be in the range of 120mm to 240mm (0.5X-1X), providing the dimension of the reflector panels perpendicular to the drivne element of about 60mm to 120mm. In contrast, at that frequency, a possible embodiment of the 10 present invention would have a reflector panel height Hp of 43mm (0.3 5IX), the dimension of the reflector panels perpendicular to the driven elements W of 9mm (0.0735A-), diameter D of the antenna of 18mm (0.147A.), driven element height Ha of 29mm (0.237X), and driven element diameter of 1.8mm (0.01471), and driven element placement of 6mm-10mm (0.05X-0.08A) from the centre axis 25. It will be appreciated 15 that these actual dimensions are for a possible embodiment only, and they will be different in other applications.

The actual dimensions will depend on the intended operating frequency of the antenna. For example, for higher design frequencies, the dimensions of the antenna in terms of 20 wavelength may be bigger than for lower operating frequencies, as the higher operating frequency design will result in smaller actual dimensions. So, for example, a particular dimension of an antenna designed for 1 GHz, may be 0.2X, whereas for a 2 GHz antenna that dimension could be 0.4X, as this would result in the same actual physical dimension. The acceptable magnitude of the dimensions will depend somewhat on 25 what is physically reasonable for the particular application of the antenna. The important point of the invention is that the dimensions for an antenna designed for a particular operating frequency are significantly smaller than those that conventional wisdom says are necessary when constructing antennae for that operating frequency.

The overall reduction in size enables the antenna to be used conveniently in a range of telecommunications devices and applications, such as handheld and mobile radio transceivers, where previously they could not because of bulky dimensions. The 102181-2 antenna 20 described could be designed for use in any suitable telecommunications equipment or system, such as the system described in NZ 520650. To provide optimal reception using the diversity antenna, circuitry can be used to allow intelligent switching between the antenna elements 22a-22c, or processing in the telecommunications equipment can perform diversity combining on all, or a selection of the received multi-path signals, according to existing techniques.

The antenna element used in the preferred embodiment described above is a standard monopole, with a feed point at the base of the antenna. However, the driven elements 23a-23c may take various alternative forms and utilise a variety of alternative feed arrangements, some of which will be described with reference to Figures 4A to 7. Alternative feed arrangements can be used to provide convenient matching to a wide variety of impedances including the standard 50ohm and 75ohm terminations. This facilitates suitable matching with the input feed line and transmission media, for example air. Figure 4A shows a symmetrical folded monopole element 40, each end 41a, 41b of which is coupled to the ground plane 21. The feed point 42 is at the apex of the fold. Figure 4B shows an alternative arrangement in which the folded monopole 46 is coupled to the ground plane 21 at one end only, with the other end providing the feed point 47. In Figure 4C, a standard monopole element 48 is utilised, but the feed point 49 is part way along the element 48, at a point providing the required impedance match. In this embodiment, the driven element 48 may have a screened and unscreened portion. This enables coupling of the feed line at the appropriate point. In each case, the outer sheath 44 of the feed coaxial cable 43 is coupled to the ground plane 21, while the conductor core 45 is coupled to the feed point.

Figure 5 shows a centre feed 51 dipole driven element 50, that is equivalent to a base feed monopole element reflected in the ground plane 21. This can be used instead of a monopole element to provide a range of advantages, where required. The dipole 50 is ground independent, so does not rely on mirrored currents flowing in the ground plane 21 or equipment on which it is mounted. Utilising this element 50 also reduces unwanted electromagnetic coupling between the antenna, and equipment. Use of the driven element 50 also reduces the interaction between the equipment and the manner in 102181-2 which it is held by a user. A user can significantly alter the antenna performance and radiation pattern, which can be mitigated by implementing a dipole 50. The dipole 50 can take on various forms, and have different types of feed points, as required.

The close proximity of the reflector significantly lowers the radiation resistance and therefore feed impedance of the associated element antenna element. Figure 6A illustrates one arrangement that can be used to reduce this problem, whereby the feed point 60 is partly up the length of a X/4 antenna that is constructed from two separate elements 61a, 61b. The separate elements enable the transmission line feed 62 to be 10 coupled part way along the element 61a, 61b. The feed impedance of a A,/4 element above a ground plane rises as the feed point moves away from the ground plane. While this arrangement works satisfactorily in an electromagnetic sense, it is mechanically inconvenient due to the physical nature of the coupling. An alternative is shown in Figure 6B, which is electromagnetically equivalent to the feed arrangement in Figure 15 6A. The outer portion 64 of the coaxial feed line 63 is extended above the ground plane 21 to shift the feed point 65 of the element to the edge of the coaxial outer portion 64. The combination of the inner conductor and the portion of the outer conductor of the coaxial cable above the ground plane forms the driven element 66.

An equivalent centre feed arrangement can also be applied to a dipole element 67 (with no ground plane), as shown in Figure 6C. The element 67 comprises a thin conductor portion 68a coupled to the inner core of a coaxial cable feed 69. A portion of the feed 68b is arranged to form part of the dipole 67 above the centre line. The coaxial feed 69 comes away from the dipole 67 at its electrical centre (zero voltage node) to ensure that 25 no net current flows on the coaxial outer. Preferably, the lower section 68c, 68d is constructed in a similar manner to the top section 68a, 68b, by connecting a thin conductor 68d to a larger diameter conductor (providing an equivalent to the coaxial outer). This provides a symmetrical radiation pattern. This is not essential, however, and any lower section that is V4 resonant could be used.

In further possible variations on the preferred embodiment, the antenna radiation pattern may be modified by changing coupling of the driven element(s). In the case of an 102181-2 antenna where only one element is driven at a time, the pattern can be modified by utilising the inherent mutual coupling existing between all the elements of the antenna. By adjusting the terminating reactance of the undriven elements, the radiation pattern of the driven element can be modified, as desired. Figure 7 shows a diversity antenna 70 5 with three elements 71a to 71c, each of which can be selected as the driven element by way of a PIN diode switch 72, or similar. Changing the length L to the feed point determines the net reactance presented to the undriven (coupled) element(s), thus changing the phase of the radiation pattern. By selecting an appropriate coupling point on the driven element, mutual coupling can be cancelled out to provide a desired 10 radiation pattern of the driven element.

Referring to Figures 8A and 8B, alternative shaped reflector panels can be utilised to reduce the overall size of the antenna. As shown in Figure 8A, the top corners 80a to 80c of the reflector panels can be rounded without significantly reducing 15 electromagnetic shielding between the segments. Alternatively, as shown in Figure 8B, reflector panels 81a to 81c are partially or fully tapered from the base to the apex 82, again without significantly affecting the shielding. Other shaped panels could also be used. In antennas where the dimension of the reflector panel perpendicular to the driven element changes the maximum value of this dimension is less than 0.2X.

In yet another possible modification to reduce size, the entire antenna, or just the driven elements, may be fully or partially encapsulated in a dielectric material 93 with a dielectric constant greater than 1. This has the effect of modifying the electric field lines in such a manner as to reduce the lengths required to achieve electrical resonance 25 of the elements. The low loss dielectric envelope 93 could be polythene, PTFE, or ceramic, for example. In a preferred implementation, the entire antenna assembly is fully encapsulated (the extent of which is shown by dotted lines 93) in Figure 9 to form a rigid solid cylinder by, for example, injection moulding. This provides a strong stable unit with a reduction in size from 20% to several hundred percent.

In an alternative implementation, the antenna is not utilised in a diversity scheme, but rather each antenna element is used simultaneously and independently. In this manner, 102181-2 different sectors of the antenna can transmit/receive different data to or from different users, on the same or different frequency.

Figure 10A shows the azimuth polar plot of the radiation pattern of one element of the 5 antenna of Figures 2a-2c. Figure 10B shows the elevation polar plot of the radiation pattern of one element of the antenna of Figures 2a-2c. Figure 11 shows the radiation pattern of one element of the antenna of Figures 2a-2c.

Mutual coupling between the driven elements occurs when part of the signal at one 10 element is added to or subtracted from the signal at another element. Mutual coupling between elements changes the radiation pattern of the element.

The change in radiation pattern can either improve the performance of the antenna or decrease the performance of the antenna depending on the amount of coupling and the 15 phase angle of the coupling. Mutual coupling between elements in the antenna can be used to tweak the antenna radiation pattern. For example in the three element antenna of Figures 2a-2c there may be mutual coupling to element one from elements two and three, mutual coupling to elements two from elements one and three and mutual coupling to element three from elements one and two. The mutual coupling may be 20 different between each element.

Figures 12 to 14 show, for a three-element antenna, examples of how the radiation pattern can be altered by allowing a small amount of the signal primarily intended to drive one element to be coupled to the other two elements. In these examples the mutual 25 coupling is the inherent coupling between the elements due to their close proximity. The phase angle of these coupled signals is modified by terminating the other two elements feed points with reactive loads. In these specific examples the terminating reactances consist open circuit 50-0hm transmission line stubs with the following electrical phase lengths: Fig. 12 140 degrees Fig. 13 150 degrees Fig. 14 160 degrees 102181-2 More generally the net amplitude and phase of mutual coupling between the elements can be achieved with a mutual coupling arrangement as shown if Fig. 15 Figure 15 shows a mutual coupling system. In this system the antenna 150 has three antenna elements (not shown) connected to three antenna feed points 151-153. The antenna feeds are connected through mutual coupling network 154 and lines 155-157 to telecommunications equipment (not shown). Signals from the telecommunications equipment pass along lines 155-157 where they may be partly superimposed on one 10 another by mutual coupling network 154. The signals are then transmitted by antenna 150 through feed points 151-153 and the antenna elements. Signals received by each of the antenna elements may also be superimposed by mutual coupling network 154 before being diversity combined and provided to the telecommunications equipment.

The foregoing describes the invention including preferred forms thereof. Alterations and modifications as will be obvious to those skilled in the art are intended to be incorporated in the scope hereof as defined by the accompanying claims. 102181-2

Claims (74)

WHAT WE CLAIM IS:

1. An antenna for telecommunications equipment including one or more electromagnetically shielded sections, each section including a driven element and one 5 or more reflectors, wherein the maximum dimension of the reflector perpendicular to the element is 0.21, where A, is the antenna operating wavelength.

2. An antenna for telecommunications equipment as claimed in claim 1 including multiple sections. 10

3. An antenna for telecommunications equipment as claimed in claim 2 wherein the antenna elements and sections are arranged for use as a diversity antenna.

4. An antenna for telecommunications equipment as claimed in any one of claims 1 15 to 3 wherein the overall antenna radius is 0.2A, or less.

5. An antenna for telecommunications equipment as claimed in any one of claims 1 to 4 wherein the overall antenna height is 0.5A, or less. 20

6. An antenna for telecommunications equipment as claimed in any one of claims 1 to 5 wherein the shielded sections are formed from one or more reflector plates.

7. An antenna for telecommunications equipment as claimed in claim 6 wherein the reflector plates are square or rectangular in shape. 25

8. An antenna for telecommunications equipment as claimed in claim 6 wherein the reflector plates have rounded top corners.

9. An antenna for telecommunications equipment as claimed in claim 6 wherein 30 the reflector plates taper towards the top edge. 102181-2 INTELLECT UAL PKUPERTY O^FlCEl OF N.z. 1 3 OCT 2004 RECEIVED - 17-

10. An antenna for telecommunications equipment as claimed in any one of claims 1 to 9 wherein the shielded sections form segments of a circle.

11. An antenna for telecommunications equipment as claimed in claim 10 when dependent on any one of claims 6 to 9 wherein a reflector plate forms a boundary edge of a segment.

12. An antenna for telecommunications equipment as claimed in claim 10 or claim 11 wherein the segments meet at a central axis.

13. An antenna for telecommunications equipment as claimed in claim 12 wherein each segment has one or more boundary edges extending radially from the axis.

14. An antenna for telecommunications equipment as claimed in claim 11 or claim 12 wherein each reflector plate forming the boundary extends from the central axis.

15. An antenna for telecommunications equipment as claimed in any one of claim 12 to 14 wherein the maximum dimension of each reflector plate perpendicular to the driven element and forming the boundary is a radius of the antenna.

16. An antenna for telecommunications equipment as claimed in any one of claims 6 to 15 wherein each antenna reflector plate has maximum dimension perpendicular to the driven element of 0.21 or less.

17. An antenna for telecommunications equipment as claimed in any one of claims 6 to 16 wherein each antenna reflector plate has a maximum dimension perpendicular to the driven element in the range of 0.041 to 0.21

18. An antenna for telecommunications equipment as claimed in any one of claims 6 to 17 wherein each antenna reflector plate has a maximum dimension perpendicular to the driven element in the range of 0.061 to 0.081. 102181-2 -18-

19. An antenna for telecommunications equipment as claimed in any one of claims 6 to 18 wherein each antenna reflector plate has a maximum dimension perpendicular to the driven element of approximately 0.071. 5

20. An antenna for telecommunications equipment as claimed in any one of claims 6 to 19 wherein each antenna reflector plate has a height of 0.51 or less.

21. An antenna for telecommunications equipment as claimed in any one of claims 6 to 20 wherein each antenna reflector plate has a height in the range of 0.11-0.51. 10

22. An antenna for telecommunications equipment as claimed in any one of claims 6 to 21 wherein each antenna reflector plate has a height in the range of 0.31-0.41

23. An antenna for telecommunications equipment as claimed in any one of claims 6 15 to 22 wherein each antenna reflector plate has a height of approximately 0.351

24. An antenna for telecommunications equipment as claimed in any one of claims 1 to 23 wherein each driven element has a height of 0.31 or less. 20

25. An antenna for telecommunications equipment as claimed in any one of claims 1 to 24 wherein each driven element has a height in the range of 0.11-0.31.

26. An antenna for telecommunications equipment as claimed in any one of claims 1 to 25 wherein each driven element has a height in the range of 0.201-0.251. 25

27. An antenna for telecommunications equipment as claimed in any one of claims 1 to 26 wherein each driven element has a height of approximately 0.231.

28. An antenna for telecommunications equipment as claimed in any one of claims 6 30 to 27 wherein the height of each driven element is lower than the height of the reflector plates. 102181-2 -19-

29. An antenna for telecommunications equipment as claimed in any one of claims 1 to 28 wherein each driven element is a monopole.

30. An antenna for telecommunications equipment as claimed in any one of claims 1 to 28 wherein each driven element is a dipole.

31. An antenna for telecommunications equipment as claimed in any one of claims 1 to 30 wherein the radiation pattern of a driven element is controlled by modifying the mutual coupling between driven elements.

32. An antenna for telecommunications equipment as claimed in any one of claims 1 to 31 wherein the antenna has a circular base.

33. An antenna for telecommunications equipment as claimed in any one of claims 6 to 32 wherein each reflector plate extends substantially to the perimeter of the base.

34. An antenna for telecommunications equipment as claimed in any one of claims 1 to 33 wherein each driven element has a diameter of 0.0151 or less.

35. An antenna for telecommunications equipment as claimed in any one of claims 1 to 34 wherein each driven element has a diameter in the range of 0.0141-0.0151.

36. An antenna for telecommunications equipment as claimed in any one of claims 12 to 35 wherein each driven element is positioned at a distance of less than 0.081 from the central axis.

37. An antenna for telecommunications equipment as claimed in any one of claims 12 to 36 wherein each driven element is positioned at a distance in the range of 0.051 to 0.081 from the central axis.

38. An antenna for telecommunications equipment including two or more electromagnetically shielded sections, each section including one or more driven 102181-2 -20- elements and one or more reflectors, wherein the maximum dimension of the reflector perpendicular to the driven element(s) is 0.2 X, where X is the antenna operating wavelength. 5

39. An antenna for telecommunications equipment as claimed in claim 38 wherein the antenna elements and sections are arranged for use as a diversity antenna.

40. An antenna for telecommunications equipment as claimed in claim 38 or claim 39 wherein the overall antenna radius is 0.2A- or less. 10

41. An antenna for telecommunications equipment as claimed in any one of claims 38 to 40 wherein the overall antenna height is 0.51 or less.

42. An antenna for telecommunications equipment as claimed in any one of claims 15 38 to 41 wherein the shielded sections are formed from one or more reflector plates.

43. An antenna for telecommunications equipment as claimed in claim 42 wherein the reflector plates are square or rectangular in shape. 20

44. An antenna for telecommunications equipment as claimed in claim 42 wherein the reflector plates have rounded top corners.

45. An antenna for telecommunications equipment as claimed in claim 42 wherein the reflector plates taper towards the top edge. 25

46. An antenna for telecommunications equipment as claimed in any one of claims 38 to 45 wherein the shielded sections form segments of a circle.

47. An antenna for telecommunications equipment as claimed in claim 46 when 30 dependent on any one of claims 42 to 45 wherein a reflector plate forms a boundary edge of a segment. 102181-2 5 -21 -

48. An antenna for telecommunications equipment as claimed in claim 46 or claim 47 wherein the segments meet at a central axis.

49. An antenna for telecommunications equipment as claimed in claim 48 wherein each segment has one or more boundary edges extending radially from the axis.

50. An antenna for telecommunications equipment as claimed in claim 47 or claim 48 wherein each reflector plate forming the boundary extends from the central axis. 10

51. An antenna for telecommunications equipment as claimed in any one of claim 48 to 50 wherein the maximum dimension of each reflector plate perpendicular to the driven element and forming the boundary is a radius of the antenna.

52. An antenna for telecommunications equipment as claimed in any one of claims 15 42 to 51 wherein each antenna reflector plate has maximum dimension perpendicular to the driven element of 0.21 or less.

53. An antenna for telecommunications equipment as claimed in any one of claims 42 to 52 wherein each antenna reflector plate has a maximum dimension perpendicular 20 to the driven element in the range of 0.041 to 0.21

54. An antenna for telecommunications equipment as claimed in any one of claims 42 to 53 wherein each antenna reflector plate has a maximum dimension perpendicular to the driven element in the range of 0.061 to 0.081. 25

55. An antenna for telecommunications equipment as claimed in any one of claims 42 to 54 wherein each antenna reflector plate has a maximum dimension perpendicular to the driven element of approximately 0.071. 30

56. An antenna for telecommunications equipment as claimed in any one of claims 42 to 55 wherein each antenna reflector plate has a height of 0.51 or less. 102181-2

57. An antenna for telecommunications equipment as claimed in any one of claims 42 to 56 wherein each antenna reflector plate has a height in the range of 0.11-0.51.

58. An antenna for telecommunications equipment as claimed in any one of claims 42 to 57 wherein each antenna reflector plate has a height in the range of 0.31-0.41

59. An antenna for telecommunications equipment as claimed in any one of claims 42 to 58 wherein each antenna reflector plate has a height of approximately 0.351

60. An antenna for telecommunications equipment as claimed in any one of claims 38 to 59 wherein each driven element has a height of 0.31 or less.

61. An antenna for telecommunications equipment as claimed in any one of claims 38 to 60 wherein each driven element has a height in the range of 0.11-0.31.

62. An antenna for telecommunications equipment as claimed in any one of claims 38 to 61 wherein each driven element has a height in the range of 0.201-0.251.

63. An antenna for telecommunications equipment as claimed in any one of claims 38 to 62 wherein each driven element has a height of approximately 0.231.

64. An antenna for telecommunications equipment as claimed in any one of claims 42 to 63 wherein the height of each driven element is lower than the height of the reflector plates.

65. An antenna for telecommunications equipment as claimed in any one of claims 38 to 64 wherein each driven element is a monopole.

66. An antenna for telecommunications equipment as claimed in any one of claims 38 to 64 wherein each driven element is a dipole. 102181-2 -23-

67. An antenna for telecommunications equipment as claimed in any one of claims 38 to 66 wherein the radiation pattern of a driven element is controlled by modifying the mutual coupling between driven elements. 5

68. An antenna for telecommunications equipment as claimed in any one of claims 38 to 67 wherein the antenna has a circular base.

69. An antenna for telecommunications equipment as claimed in any one of claims 42 to 68 wherein each reflector plate extends substantially to the perimeter of the base.

70. An antenna for telecommunications equipment as claimed in any one of claims 38 to 69 wherein each driven element has a diameter of 0.0151 or less.

71. An antenna for telecommunications equipment as claimed in any one of claims 15 38 to 70 wherein each driven element has a diameter in the range of 0.0141-0.0151.

72. An antenna for telecommunications equipment as claimed in any one of claims 48 to 71 wherein each driven element is positioned at a distance of less than 0.081 from \ the central axis. 20

73. An antenna for telecommunications equipment as claimed in any one of claims 48 to 72 wherein each driven element is positioned at a distance in the range of 0.051 to 0.081 from the central axis. 25

74. An antenna for telecommunications equipment substantially as herein described with reference to the accompanying drawings. Tail EU&CKoia,rS Uiivulexl By the'authorised agents A. J.fPAl INTELLECTUAL PROPERTY OFFICE OF N.Z 2 3 JAN 2004 RECEIVED 102181-2