GB2439760A

GB2439760A - Compact multi-frequency antenna with multiple ground and radiating elements

Info

Publication number: GB2439760A
Application number: GB0613075A
Authority: GB
Inventors: Maksim Berezin; Motti Elkobi; Aviv Shachar
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 2006-07-03
Filing date: 2006-07-03
Publication date: 2008-01-09
Anticipated expiration: 2026-07-03
Also published as: TW200816561A; GB2439760B; WO2008005703A3; WO2008005703A2; WO2008005703B1; GB0613075D0

Abstract

An antenna comprises an insulating substrate 403 with first and second conductive portions 501, 502 on opposite respective surfaces of the said substrate. The first said portion 501 provides a first quarter wavelength resonator for frequencies in the range of 800 MHz to 1000 MHz and the second said portion 502 provides a second quarter wavelength resonator for frequencies in the range of 1200 MHz to 2000 MHz. The said first and second radiators 501, 502 have no direct galvanic connection. The substrate 403 also carries a ground plane portion 509. The substrate 403 is separated and supported by insulating support columns 405 from a conducting support member 301 which provides at least part of a ground plane. The conducting support member 301 may be electrically connected via a conductive shorting pin 411 to the ground plane portion 509 and the second conducting portion 502. The central conductor 505 of a coaxial cable 409 may be soldered to the first radiator so that it can supply a feed signal to the said first radiator 501. The outer conductor 508 of the coaxial cable 409 may supply a feed signal to the second radiator 502 via the third conducting portion 509 and conductive via elements 511. Other conductive elements associated with an imager device may be used to improve the impedance matching of the antenna elements. The compact, efficient multi-frequency antenna may be suitable for use in a wireless communication device.

Description

TITLE: ANTENNA APPARATUS

FIELD OF THE INVENTION

The present invention relates to antenna apparatus.

In particular, the invention relates to antenna apparatus for a wireless communication device, and more particularly a portable or handheld communication device.

BACKGROUND OF THE INVENTION

Portable handheld wireless communication devices such as cellular telephones, portable radios, data communication devices, and the like employ an antenna to radiate and receive electromagnetic signals transmitted over the air. Monopole antennas are widely used as RF (radio frequency) radiators in such communication devices. As such communication devices become more complex, e.g. by the incorporation of additional functional components such as cameras, advanced loudspeakers and the like, extra functional requirements are imposed on the antenna. There is also an ongoing search for ways to reduce the overall size and weight of such communication devices, including the antenna.

Thus, it is expected in the future that the space available in a portable communication device for the antenna will decrease, since the overall size of the device will continue to decrease and/or the device will have to accommodate other functional components at the expense of the antenna. However, reducing the size of the antenna may negatively impact upon its antenna gain.

This follows from the fact that an antenna is used to transform a bounded wave into a radiating wave and vice versa. This requires careful selection of where components are placed in the communication device to give suitable operation of the antenna.

Thus there is a need for new antenna apparatus which addresses the above problems.

SU)4ARY OF THE INVENTION According to the present invention there is provided antenna apparatus as defined in claim 1 of the accompanying claims.

According to the present invention in a second aspect there is provided a wireless communication device as defined in claim 26 of the accompanying claims.

Further features of the present invention are as defined in the accompanying dependent claims and are disclosed in the embodiments of the invention to be described.

Embodiments of the present invention will be described by way of example with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, in which like reference numerals refer to identical or functionally similar elements throughout the different drawings and which

together with the detailed description later are

incorporated in and form part of the specification, serve to illustrate various embodiments and to explain various principles and examples of the present invention. In the accompanying drawings: FIG. 1 is a front view of an RF communication device incorporating antenna apparatus embodying the invention.

FIG. 2 is a rear perspective view of the communication device of FIG. 1 with part of a casing of the device removed to show internal components of the device including components of antenna apparatus embodying the invention.

FIG. 3 is an enlarged perspective view of an assembly shown in FIG. 2 removed from the communication device.

FIG. 4 is an enlarged perspective view of a sub-assembly of the assembly shown in FIG. 3.

FIG. 5 is an enlarged view of an antenna board of the sub-assembly of FIG 4.

FIG. 6 is a view of a rear surface of the antenna board of FIG. 5.

FIG. 7 is a graph of VSWR (voltage standing wave ratio) versus frequency for a specific illustrative antenna apparatus embodying the invention.

FIG. 8 shows a plot in two dimensions in a y-z plane illustrating the omnidirectional radiation pattern obtained in that plane by a specific illustrative antenna apparatus embodying the invention in a first frequency range.

FIG. 9 shows a plot in two dimensions in an x-z plane illustrating the omnidirectional radiation pattern obtained in that plane in a first frequency range by the same specific illustrative antenna apparatus which produced the plot in FIG. 8.

FIG. 10 shows a plot in two dimensions in an x-y plane illustrating the omnidirectional radiation pattern obtained in that plane in a first frequency range by the same specific illustrative antenna apparatus which produced the plot in FIG. 8.

FIG. 11 shows a plot in two dimensions in a y-z plane illustrating the omnidirectional radiation pattern obtained in that plane in a second frequency range by the same specific illustrative antenna apparatus which produced the plot in FIG. 8.

FIG. 12 shows a plot in two dimensions in an x-z plane illustrating the omnidirectional radiation pattern obtained in that plane in a second frequency range by the same specific illustrative antenna apparatus which produced the plot in FIG. 8.

FIG. 13 shows a plot in two dimensions in an x-y plane illustrating the omnidirectional radiation pattern obtained in that plane in a second frequency range by the same specific illustrative antenna apparatus which produced the plot in FIG. 8.

Skilled artisans will appreciate that elements or components shown in the drawings are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements shown in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.

Skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Before describing in detail embodiments that are in accordance with the present invention, it is observed that in this document, relational terms such as first', second', top', bottom' and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms comprising', comprises', including', includes', having' and the like are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such process, method, article or apparatus.

In accordance with an embodiment of the invention, an antenna apparatus for a wireless communication device comprises an insulating antenna substrate having on a first surface thereof a first conducting portion providing a first radiator and on a second surface thereof a second conducting portion providing a second radiator, the first conducting portion and the second conducting portion being galvanically unconnected, the insulating antenna substrate also having thereon a first part of a conducting ground plane comprising a third conducting portion, the apparatus also including, galvanically connected to the first part of the conducting ground plane, a second part of the conducting ground plane, the second part of the conducting ground plane comprising a conducting support member, the insulating substrate being separated from but supported on the conducting support member. The first conducting ground portion may include, galvanically connected to the third conducting portion, a fourth conducting portion.

The antenna apparatus embodying the invention may be operable to provide transmission and/or reception of electromagnetic radiation signals in a first operational frequency range with omnidirectional radiation patterns for three mutually orthogonal directions of the polarization vector (e.g. axes x, y and z referred to later with reference to FIG. 4) and transmission and/or reception of electromagnetic radiation signals in a second operational frequency range also with omnidirectional radiation patterns for three mutually orthogonal directions of the polarization vector. The second frequency range may have a centre frequency which is substantially higher in frequency than a centre frequency of the first frequency range.

The first radiator and the second radiator may comprise quarter wave resonators.

FIG. 1 is a front view of an illustrative radio wireless communication device 100 incorporating antenna apparatus embodying the invention. The device 100 is a handset for data and/or voice communications and includes a casing 103. It will be appreciated by those of ordinary skill in the art that the invention is further applicable to any wireless communication device.

A front surface 107 of the casing 103 includes in a lower region a keypad 109 and various buttons and control actuators 110 for data entry and function control. The front surface 107 includes in an upper region a display 111 for the display of data.

FIG. 2 is a rear perspective view (shown from behind the front face 107 of the casing 103) . In FIG. 2, a rear portion of the casing 103 is removed to show components mounted internally in the casing 103. The end of the casing 103 shown to the right in FIG. 2 corresponds to the upper end shown in FIG. 1. Fitted inside an enclosure formed by the casing 103 is a chassis 201 formed of lightweight conducting metallic material which serves to hold internal components of the device 100. A board 203, e.g. made of printed circuit board material, having a conducting surface extends lengthwise inside the device 100 on the chassis 201. The board 203 is held by various fixing members, including, attached to the chassis 201, a clip 205, blocks 207 and studs 209. An assembly 211 of components is mounted on the board 203 near the upper end of the board 203.

FIG. 3 is an enlarged perspective view of the assembly 211 removed from the device 100. The assembly 211 is formed on a conducting support member 301. One function of the conducting support member 301 is to fix and galvanically connect the assembly 311 to the chassis 201 through the board 203 (FIG. 2) . This is achieved by studs made of conducting material (not shown) fitted through holes 303 (one of which is shown in FIG. 3) formed in flanges 304 (one of which is shown in FIG. 3) The conducting support member 301 together with a conducting layer 305 beneath the conducting support member 301 may also form a protective housing for a component device of the communication device 100, such as a radio transceiver (not shown) formed on the board 203. The conducting support member 301 also forms part of antenna apparatus embodying the invention to be described later. The conducting support member 301 and the conducting layer 305 provide additional galvanic connection between conducting material of the board 203 and part of an electrically conducting ground plane of an antenna board which forms part of antenna apparatus embodying the invention to be described later.

An imager device 307 is provided at the upper end (the front end as shown in FIG. 3) of the device 100.

Such a device may for example be used for data collection by bar code reading in a known manner. The imager device 307 includes several sub-components including a first insulating board 309, such as a printed circuit board, having a portion of conducting material (not shown) formed thereon, e.g. from a shaped metallic layer of conducting material such as copper.

The imager device 307 also includes, separated from the first insulating board 309, a second insulating board 310, which may also be a printed circuit board having a portion of conducting material (not shown) formed thereon, e.g. from a shaped metallic layer of conducting material such as copper. The conducting materials on the first insulating board 309 and the second insulating board 310 are parasitic conductors which form part of antenna apparatus embodying the invention and are referred to later.

The imager device 307 is held in position by an insulating holder 311 fixed to the chassis 201 by studs made of conducting material (not shown) fitted through the holes 303 in the flanges 304. An antenna sub-assembly 313 is fitted on the conducting support member 301.

An enlarged, more detailed perspective view of the antenna sub-assembly 313 is shown in FIG. 4. The antenna sub-assembly 313 in FIG. 4 is shown removed from the other components of the assembly 211 apart from the conducting support member 301. A layer 401 of dielectric material is deposited on the conducting support member 301. The sub-assembly 313 includes an antenna board 403 which serves as the insulating antenna substrate referred to earlier. The antenna board 403, e.g. made from printed circuit board material, is held a fixed distance away from the conducting support member 301 by the layer 401 and by insulating support columns 405 (one of which is shown in FIG. 5) and screws 407 fitted to the support columns 405. Thus, the antenna board 403 and the conducting support member 301 have facing surfaces which are parallel. The antenna board 403 is shaped to fit into the internal layout of the device 100. A coaxial cable 409 is welded by soldering to the antenna board 403. The coaxial cable 409 delivers radio frequency signals between the antenna board 403 and an RF transceiver (not shown) of the device 100, which may for example be housed inside an enclosure formed by the support member 301 and the conducting layer 305. A connector 411 comprising a conducting shorting pin extends vertically from the antenna board 403 and provides a galvanic connection between the antenna board 403 and the conducting support member 301. The connector 411 is part of antenna apparatus embodying the invention and is referred to later.

Also shown in FIG. 4 are Cartesian coordinate axes x, y and z which are fixed relative to the construction of the device 100. The axis x is parallel to the longer sides of the antenna board 403. The axis y is perpendicular to the axis x and is also in the plane of the antenna board 403; it is parallel to an axis of the casing 103. The axis z is perpendicular to the axes x and y and is parallel to the support columns 405 extending vertically between the conducting support member 301 and the antenna board 403. The axes x, y and z are referred to later.

FIG. 5 is an enlarged view of a surface of the antenna board 403 as seen from the rear of the casing 103 (FIG. 1), and FIG 6 is an enlarged view of an opposite surface of the antenna board 403. The surface of the antenna board 403 shown in FIG. 5 will be referred to as the front surface as it is the surface seen when the antenna board 403 is fitted in the device 100 as shown in FIG. 3. The surface shown in FIG. 6 will be referred to as the rear surface as it is behind the front surface. A first conducting portion 501 which serves as a first radiator is formed on the front surface of the antenna board 403. The first conducting portion 501 is in the form of an elongate conducting strip, for example formed of deposited metallic material such as copper, having a shape which has three sides and approximates to a U' shape so that its length is accommodated on the limited surface are area available on the antenna board 403. A conducting region 503 of enlarged area (relative to the area per unit length of the first portion 501) is formed at an end of the first conducting portion 501. The conducting region 503 serves as a land or feed point to which an inner (live') conductor 505 of the coaxial cable 409 is welded, e.g. by soldering 507, for delivery of radio frequency signals to or from the first conducting portion 501. A second conducting portion 502 indicated by a dashed line in FIG. 5 and shown in FIG. 6 is formed on the rear surface of the antenna board 403. The second conducting portion 502 serves as a second radiator. The second conducting portion 502 is not galvanically connected to the first conducting portion 501. The second conducting portion 502 has a selected shape as shown in FIG. 6 including a sloping side 513, for enhancing bandwidth of the resonance obtained in two desired frequency ranges as illustrated later with reference to FIG. 7. The insulating antenna board 403 has thereon further conducting portions which form part of an electrically conducting ground plane of antenna apparatus embodying the invention. This is the first part of the conducting ground plane referred to earlier. The further conducting portions forming part of this ground plane part comprise (i) a third conducting portion 509 which is formed on the front surface of the antenna board 403 in an upper corner region thereof as shown in FIG. 5; and (ii) a fourth conducting portion 512 which is formed on the rear surface of the antenna board 403 in an upper corner region thereof as shown in FIG. 6. The fourth conducting portion 512 is located directly behind the third conducting portion 509 and has a shape and size which, in reverse, match the shape and size of the third conducting portion 509 whereby the third conducting portion 509 when projected onto the fourth conducting portion 512 has an outline which coincides with that of the fourth conducting portion 512. Conducting vias 511 which pass through the insulating antenna board 403 provide galvanic connections between the third conducting portion 509 and the fourth conducting portion 512. The first conducting portion 501 does not have a galvanic connection to the ground plane part comprising the third conducting portion 509 and the fourth conducting portion 512. The second conducting portion 502 is galvanically connected to the fourth conducting portion 512. In fact, the second conducting portion 502 and the fourth conducting portion may comprise a common conducting portion. A dashed line 514 in FIG. 6 indicates a notional boundary between the second conducting portion 502 and the fourth conducting portion 512.

As shown in FIG. 5, the coaxial cable 409 has an insulating sleeve 506 from which the inner conductor 505 emerges to be welded at the soldering 507. The insulating sleeve 506 carries an outer conductor 508, e.g. in the form of a conventional braided multiwire, which is welded to the third portion 509 by soldering 510.

The communication device 100 which has been described above with reference to FIGS. 1 to 6 includes antenna apparatus embodying the invention including the following primary parts: (i) the antenna board 403 including thereon the first conducting portion 501, the second conducting portion 502 and the electrically conducting ground plane part formed comprising at least the third conducting portion 509 (and optionally the fourth conducting portion 512 connected to the third conducting portion by the conducting vias 511); (ii) the conducting support member 301; (iii) the connector 411 forming a galvanic connection between the electrically conducting ground plane part of the insulating antenna board 403 and the conducting support member 301.

The following parts also contribute to the construction and operation of the antenna apparatus embodying the invention: (iv) the coaxial cable 409; (v) the conducting layer 305 by its galvanic connection to the conducting support member 301; (v) conducting material on the board 203 by its galvanic connection to the conducting support member 301 and to the conducting layer 305; (vi) the chassis 201 by its galvanic connection to the conducting material on the board 203; (vii) conducting material of the first board 309 and the second board 310 of the imager device 307; and (viii) the layer 401 of dielectric material (by its effect on the separation as an electrical length between the antenna board 403 and the conducting support member 301) Operation of these parts as the antenna apparatus embodying the invention is as given in the following description. Operation is intended to take place in one of two frequency ranges which will be called respectively a lower frequency range' and a higher frequency range' because the frequency of operation is higher in one of the ranges than in the other range.

Examples of these ranges are given later.

An RF (radio frequency) signal for transmission is delivered from an RF transceiver (not shown) by the coaxial cable 409 and is coupled by the soldering 507 at the region 503 of enlarged area into the first conducting portion 501 from the inner conductor 505 and by the soldering 510 of the outer conductor 508 to the third portion 509. The first conducting portion 501 of the antenna board 403 has an electrical length which is equivalent to a quarter wave at the wavelength of a centre frequency of operation in the lower frequency range and thereby provides a quarter wave radiator in that range. The second conducting portion 502 which has galvanic connection to the third conducting portion 509, has an electrical length which is equivalent to a quarter wave at the wavelength of a centre frequency of operation in the higher frequency range and thereby provides a quarter wave radiator in that range. There is a difference between the electrical lengths of the first conducting portion 501 and the second conducting portion 502 which is equivalent to a quarter wave at the wavelength of a central frequency of operation in the higher frequency range. RF signals for transmission by the second conducting portion 502 are delivered via the coaxial cable 509 to the third conducting portion 509 and through the conduction vias 511 to the fourth conducting portion 512 and are galvanically coupled into the second conducting portion 502.

In a reception mode, RF radiation signals received in an incoming direction, by the first conducting portion 501 and the second conducting portion 502 are coupled into the coaxial cable 509 and are delivered by the coaxial cable 509 to the RF transceiver (not shown) of the device 100.

As noted earlier, the third conducting portion 509 and the fourth conducting portion 512, galvanically connected to the third conducting portion 509 by the vias 511, form an electricafly conducting ground plane part on the insulating antenna board 503. As is well known to those skilled in the art, a ground plane (alternatively known as a counterpoise) is a conducting surface (not necessarily a planar surface) needed for the antenna to operate efficiently. The ground plane of the antenna apparatus embodying the invention is completed by further parts galvanically connected by the connector 411 to the part comprising the third conducting portion 509 and the fourth conducting portion 512 and the conducting support member 301. The further parts comprise a galvanically connected combination of the conducting support member 301, the conducting material on the insulating board 203 and the chassis 201. These further parts are referred to collectively herein as the second' part of the ground plane.

When the antenna apparatus embodying the invention operates to transmit or receive a signal in the lower frequency range, RF electrical currents flow in the x-y plane, principally along the axes x and y, defined by the axes x, y, and z shown in FIG. 4. Similarly, when the antenna apparatus embodying the invention operates to transmit or receive a signal in the higher frequency range, RF electrical currents flow in the x-y plane, principally along the axes x and y, defined by the axes x, y, and z shown in FIG. 4. These various currents in both the low and high frequency ranges produce RF

electromagnetic fields having an omnidirectional

radiation pattern, as illustrated by gain results given later, with polarization vector (electric vector) principally along the x and y axes.

In addition, the vertical separation along the z axis (as shown in FIG. 4) between (1) the conducting support member 301 and (ii) the conducting portions 501, 502 and the electrically conducting ground plane part of the insulating antenna board 403; is selected to create

electromagnetic fields having an omnidirectional

radiation pattern, as illustrated by gain results given later, with polarization vector component along the z axis. The vertical separation is selected to be from O.03A (three hundredths of A) to 0.05A (five hundredths of A) where A is the wavelength for the centre frequency of operation of the lower frequency range. This is equivalent to from 0.06A1 to 0.1A1, where A1 is the wavelength at the centre frequency of the higher frequency range.

Furthermore, further electrical currents are induced in the conducting material on the first board 309 and the conducting material on the second board 310 by the capacitive coupling between the those materials and the conducting portions 501, 502 and the electrically conducting ground plane part of the insulating antenna board 403. The first insulating board 309 and the second insulating board 310 and the conducting material formed on them are disposed at an acute angle relative to the x-y plane. In view of the angular separation between the antenna board 403 and each of the first board 309 and the second board 310, these further electrical currents in the conducting material of the boards 309 and 310 improve impedance matching in the lower and higher frequency ranges of the antenna apparatus embodying the invention.

As a result of the various currents which have been described above, an electromagnetic radiation pattern is produced by the antenna apparatus embodying the invention in both of the low and high frequency ranges which is omnidirectional in three dimensions, as represented by the x, y and z axes, of the polarization vector of the radiation.

Example 1

A specific illustrative example of an antenna apparatus embodying the invention made as described above with reference to FIGS. 3 to 6 was targeted for use in each of a particular low frequency range and a particular high frequency range. The two particular frequency ranges, which are of commercial interest, are as follows: Frequency Range 1 from 824 (eight hundred and twenty four) MHz (Megahertz) to 960 (nine hundred and sixty) MHz; and Frequency Range 2 from 1710 (one thousand, seven hundred and ten) MHz to 1990 (one thousand, nine hundred ninety) MHz. The Frequency Range 1 embraces operation in the following well known system types: GSM (Global System for Mobile communications) and GPRS (General Packet Radio service) and CDMA (Code Division Multiple Access) . The Frequency Range 2 embraces operation in the following well known system types operating at different frequencies: CDMA, GSM, and GPRS. Of course, other specific examples of the antenna apparatus embodying the invention can, by use of suitable design scaling well known in the art, be targeted at operation in other frequency ranges such as covering 2.4 GHz (GigaHertz) for use in Bluetooth (RTM) or WLAN (Wireless Local Area Network) systems or 4.9 GHz for use in other WLAN systems.

In the specific illustrative example for use in the Frequency Ranges 1 and 2, the antenna apparatus had the following specific properties: 1) Dimensions of conducting portions on the antenna board 503 as shown in FIG. 5 were as follows: (i) length of the lower horizontal strip of the portion 501: 26 mm; (ii) length of the upper horizontal strip of the portion 501 (including the enlarged region 503): 25.63 mm; (iii) length of the sloping strip of the portion 501: 16.45 mm; (iv) maximum distance between the left side edge of the portion 502 and the right side edge of the portion 514: 36.19 mm; (v) length of the upper straight side edge portion of the antenna board 403: 23.52 mm; (vi) length of the left side edge of the portion 502: 7.09 mm; (vii) length of the right side edge of the portion 502 (adjacent to the portion 514) : 8.51 mm; (viii) length ofthe lower horizontal edge portion of the portion 502: 10.13 mm; (ix) length of the right side edge of the portion 509: 16.88 mm; (x) length of lower sloping edge of the portion 502: 18.59 mm; (xi) length of lower straight edge of the portion 509: 5.01 mm.

2) The vertical separation along the z axis of the antenna board 403 and the conducting support member 301 was selected for the Frequency Range 1 to be equivalent to an electrical length of 0.37A (zero point three seven lambda); or for the Frequency Range 2 was selected to be equivalent to an electrical length of 0.077 A (zero point zero seven seven lambda), where A (lambda) is the wavelength at the centre of the respective frequency range. A single result applies for both Frequency Ranges 1 and 2.

3) The board 403 was made of the industry standard material FF4 having a thickness of 0.8 (zero point eight) mm (millimetres), and dielectric properties of relative permittivity () = 4.6 (four point six) and tangent of dielectric loss angle (tan 5) = 0.019 (zero point zero one nine) . The conducting material of the conducting portions on each of the boards 203, 309, 310 and 403 was copper.

4) The layer 401 of dielectric material had a thickness of 1.5 mm (one point five millimetres) and was made of ABS polymer material commercially available under the trade name CYCOLAC G368 ABS. This material has a relative permittivity (Er) of 2.8 (two point eight) and a tangent of dielectric loss angle (tan 5) value of 0.014 (zero point zero one four) . Consequently, the layer 40 causes the separation as an apparent electrical length between the antenna board 403 and the conducting support member 301 to be greater than the actual physical gap size by a factor of about 1.22. The actual physical gap between the layer 401 and the conducting support member 301 was 10.2 (ten point two) millimetres.

Properties of the specific antenna apparatus made as described in Example 1 were measured as follows. The VSWR (voltage standing wave ratio) was measured as a function of frequency in a well known manner. As is well known to those of ordinary skill in the antenna design art, VSWR is a measure of the matching performance of an antenna (relative to a standard impedance of fifty ohms) in its operational frequency range. The VSWR may be considered to be suitably low if has a value of between one and an arbitrary upper level of three.

FIG. 7 is a graph of VSWR versus frequency measured in MHz (MegaHertz) showing a curve 700 plotted for the specific antenna apparatus made as described in Example 1. A dashed line 701 indicates a threshold VSWR value of three. The curve 700 beneficially shows a VSWR value of three or less, in other words the VSWR is not above the threshold VSWR indicated by the line 701, in two regions, namely a first region 702 and a second region 703. The first region 702 extends from about 800 MHz (MegaHertz) to about 1000 MHz, and the second region 705 extends from about 1200 MHz to about 2000 MHz.

The two frequency ranges of commercial interest, namely Frequency Range 1 and Frequency Range 2 referred to earlier, fall suitably in the first region 702 of the curve 700 and the second region 703 of the curve 700 respectively. Specific measured points on the curve 700 in the first region 702 are indicated by three markers Ml, M2 and M3. Markers Ml and M3 indicate the respective ends of the Frequency Range 1. Specific measured points on the curve 700 in the second region 703 are indicated by three markers M4, M5 and M6. Markers M4 and M6 indicate the respective ends of the Frequency Range 2.

FIG. 7 also shows a table, Table 1, in which the measured VSWR and frequency for each of the markers Ml to M6 is given. For each of the markers Ml to M6 the VSWR value measured, as listed in Table 1, is a low value which is beneficially less than 2.5.

The specific antenna apparatus made as described in Example 1 showed in both of the Frequency Range 1 and the Frequency Range 2 omnidirectional radiation patterns for the radiation polarization vector in three dimensional space, as represented by the x, y and z axes shown in FIG. 4. In particular, the following gain properties were obtained.

1) Frequency Range 1 from 0.82 to 0.96 GHz At about the centre frequency of the range, 900 MHz, radiation patterns and maximum gain were measured for the polarization vectors in three dimensions and is illustrated in FIGS. 8 to 10. FIG. 8 shows a plot 800 in two dimensions in the y-z plane illustrating the omnidirectional radiation pattern obtained in that plane. The maximum gain with the polarization vector along the x axis was -3.4 (minus three point four) dBi (decibels over isotropic) . FIG. 9 shows a plot 900 in two dimensions in the x-z plane illustrating the omnidirectional radiation pattern obtained in that plane. The maximum gain measured for the polarization vector along the y axis was 0.99 (zero point nine nine) dBi. FIG. 10 shows a plot 1000 in two dimensions in the x-y plane illustrating the omnidirectional radiation pattern obtained in that plane. The maximum gain measured for the polarization vector along the z axis was 0.89 (zero point eight nine) dBi.

2) Frequency Range 2 from 1.71 to 1.99 GHz At about the centre frequency of the range, 1850 MHz, radiation patterns and maximum gain were measured for the polarization vectors in three dimensions and is illustrated in FIGS. 11 to 13. FIG. 11 shows a plot 1100 in two dimensions in the y-z plane illustrating the omnidirectional radiation pattern obtained in that plane. The maximum gain with the polarization vector along the x axis was 1.9 (one point nine) dBi. FIG. 12 shows a plot 1200 in two dimensions in the x-z plane illustrating the omnidirectional radiation pattern obtained in that plane. The maximum gain with the polarization vector along the y axis was -1.82 (minus one point eight two) dBi. FIG. 13 shows a plot 1300 in two dimensions in the x-y plane illustrating the omnidirectional radiation pattern obtained in that plane. The maximum gain with the polarization vector along the z axis was 0.57 (zero point five seven) dBi.

In the foregoing specification, specific

embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below.

Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.

Claims

CLAIMS

1. Antenna apparatus for a wireless communication device comprising an insulating antenna substrate having on a first surface thereof a first conducting portion providing a first radiator and on a second surface thereof a second conducting portion providing a second radiator, the first conducting portion and the second conducting portion being galvanically unconnected, the insulating antenna substrate also having thereon a first part of a conducting ground plane comprising a third conducting portion, the apparatus also including, galvanically connected to the first part of the conducting ground plane, a second part of the conducting ground plane, the second part of the conducting ground plane comprising a conducting support member, the insulating substrate being separated from but supported on the conducting support member.

2. Antenna apparatus according to claim 1 wherein the first conducting ground portion includes, galvanically connected to the third conducting portion, a fourth conducting portion.

3. Antenna apparatus according to claim 2 including a conducting shorting pin galvanically connected to the fourth conducting portion.

4. Antenna apparatus according to claims 3 wherein the conducting shorting pin is also galvanically connected to the conducting support member.

5. Antenna apparatus according to claim 2, claim 3 or claim 4 wherein the third conducting portion is on the same surface of the antenna substrate as the first conducting portion and is galvanically unconnected to the first conducting portion.

6. Antenna apparatus according to claim 5 wherein the fourth conducting portion is on the same surface of the antenna substrate as the second conducting portion and is galvanically connected to the second conducting portion.

7. Antenna apparatus according to any one of the preceding claims which is operable to provide transmission and reception of electromagnetic radiation signals in first and second operational frequency ranges by the first conducting portion and the second conducting portion, the second frequency range having a centre frequency which is higher in frequency than a centre frequency of the first frequency range.

8. Antenna apparatus according to any one of the preceding claims wherein the first conducting portion and the second conducting portion comprise quarter wave radiators.

9. Antenna apparatus according to any one of the preceding claims wherein the first conducting portion and the second conducting portion have electrical lengths which differ by an amount equivalent to a quarter wavelength at a frequency of operation.

10. Antenna apparatus according to any one of the preceding claims including a coaxial cable for feeding radio frequency signals for transmission or reception of electromagnetic radiation signals, the coaxial cable having an inner conductor galvanically connected to the first conducting portion and an outer conductor galvanically connected to the third conducting portion.

U. Antenna apparatus according to any one of the preceding claims wherein a surface of at least one conducting portion of the insulating antenna substrate and a surface of the conducting support member are parallel surfaces.

12. Antenna apparatus according to claim 11 wherein the parallel surfaces have a separation which is equivalent to an electrical length of from O.03A (zero point zero three times lambda) to O.05X (zero point zero five times lambda) where X (lambda) is a wavelength of operation for a lower frequency range or from O.06A (zero point zero six times lambda) to O.1A (zero point one times lamda) for a higher frequency range.

13. Antenna apparatus according to any one of the preceding claims including a layer of dielectric material between the insulating antenna substrate and the conducting support member to reduce the physical separation between the insulating antenna substrate and the conducting support member needed to obtain a separation which is equivalent to a desired electrical length.

14. Antenna apparatus according to any one of the preceding claims wherein the first conducting portion has first and second elongate strip portions which are parallel and a third elongate strip portion joining ends of the first and second portions.

15. Antenna apparatus according to claim 14 wherein the second conducting portion is wider than the strip portions of the first conducting portion and has a first elongate side which is parallel to the first and second strip portions of the first conducting portion and has a second elongate side which is sloping relative to its first elongate side.

16. Antenna apparatus according to any one of the preceding claims including at least one further conducting member providing a parasitic conductor capacitively coupled to the first conducting portion and to the second conducting portion and to the first electrically conducting ground plane part of the insulating antenna substrate.

17. Antenna apparatus according to claim 16 wherein the at least one further conducting member comprises a conducting portion deposited on a further insulating substrate.

18. Antenna apparatus according to claim 16 or claim 17 wherein the at least one further conducting member has a surface which is disposed angularly with respect to the insulating antenna substrate and with respect to an axis of separation of the insulating antenna substrate and the conducting support member.

19. Antenna apparatus according to any one of the preceding claims wherein the conducting support member is galvanically connected to one or more further conducting members which extend the surface area of the ground plane.

20. Antenna apparatus according to claim 19 including a conducting chassis to which the conducting support member is galvanically connected.

21. Antenna apparatus according to claim 19 or claim 20 including a further substrate having a further conducting portion formed thereon, the further conducting portion being galvanically connected to the conducting support member and to the conducting chassis.

22. Antenna apparatus according to any one of the preceding claims including a plurality of insulating support columns supporting the antenna substrate on the conducting support member.

23. Antenna apparatus according to any one of claims 7 to 22 wherein the first frequency range includes frequencies from eight hundred and twenty four MegaHertz to nine hundred and sixty MegaHertz and the second frequency range includes frequencies from one thousand, seven hundred and ten MegaHertz to one thousand, nine hundred and ninety MegaHertz.

24. Antenna apparatus according to any one of the preceding claims which in operation provides an omnidirectional radiation pattern for three mutually orthogonal spatial orientations of the polarization vector for at least two frequency ranges.

25. Antenna apparatus according to any one of the preceding claims and substantially as herein described with reference to the accompanying drawings.

26. A wireless communication device incorporating antenna apparatus according to any one of the preceding claims.