DE60122698T2 - Multi-band antenna - Google Patents

Abstract

An antenna comprising a conductive patch arranged to resonate when excited by an electromagnetic signal, and a feed mechanism arranged to provide electromagnetic signals to the conductive patch. For a generally rectangular patch, the feed mechanism is arranged to feed electromagnetic signals to a point substantially on, or in-line with, a diagonal of the patch. Feeding the conductive patch in this manner enables the patch to resonate in a plurality of discrete frequency bands. This means that the antenna is capable of multi-band operation without the need for additional resonating patches, shorting pins, matching circuits or multiple feed points. In a preferred embodiment, the patch includes one or more slots for manipulating the performance of the antenna. <IMAGE>

Description

The The present invention relates to multi-band antennas, and more particularly Mehrbandplanarantennen.

BACKGROUND THE INVENTION

Lots Applications require one antenna to receive signals in two or more separate frequency bands can send and receive. For example, in the field of mobile telecommunications Mobile telecommunications networks in one or more different Working frequency bands, which can vary from country to country. Therefore, must Mobile phones work in more than one frequency band can, if they are using more than one mobile network using different frequency bands, to be compatible (this is sometimes called presence of Change of location functionality designated). A multiband antenna is an antenna that can be used in more can work as a frequency band.

planar antennas, such as microstrip planar antennas, are an antenna shape with increasing popularity. Planar antennas have a relative Compact design, are relatively lightweight, relatively simple produce and therefore relatively inexpensive. In addition, planar antennas for the internal Use suitable, i. you can in a telecommunication device, e.g. a mobile phone handset, to get integrated. This not only increases the aesthetic appeal of the device, but the antenna is also protected, which makes it less susceptible to damage. Another Advantage of planar antennas is that they, for example arranged in a telephone receiver could be, that during the radiation emitted by the user, mainly directly from the user of the listener is routed away.

It are earlier Attempts have been made to provide multi-band planar antennas. These attempts involve combining two planar antennas one above the other or side by side or the use of a matching network. These Antennas have the disadvantage that they are large and complex and their Manufacturing can therefore be relatively difficult and costly. Other experiments included the combination of slots and shorting pins, however have to such antennas are relatively large and are for that reason the installation in modern telecommunications devices, in particular Telephone handset, not suitable. The problem of size is aggravated by the fact that many mobile telecommunications networks operate in relatively low frequency bands, where a low frequency operation is usually a large planar antenna requires.

JY Sze and KL Wong, "Broadband Rectangular Microstrip Antenna with Pair of Toothbrush Shaped Slots", Electronic Letters, Vol. 34, No. 23, 12.11.1998, pp. 2186-2187, XP6010604 discloses an antenna having the features of the preamble of Claim 1. JF Zurcher and FE Gardiol, "Broadband Patch Antennas", 1998, Section 2.5. "Broadbanding" in Section 2.5.2., Discloses a folded dipole antenna that includes a centrally-located H-shaped slot The antennas of each of these documents can operate in two resonant modes whose frequencies are sufficiently close to each other to serve as a single broad band resonance mode. The patent of the United States US 5,955,995 (Silverstein) discloses a planar antenna fed at one corner of the plate, causing the antenna to resonate at two adjacent frequencies. None of these antennas achieve resonance in several separate frequency bands. US 5,955,995 discloses the preamble of claim 1.

It There is therefore a need for improved multi-band planar antennas.

SUMMARY THE INVENTION

The The invention provides a flat antenna comprising: a generally rectangular conductive Plate, opposed by a first and second pair Pages is delimited; a ground plane; a dielectric substrate between the plate and the ground plane; a feeding mechanism for applying electromagnetic signals to a feed point, the yourself on the conductive Plate is located; and one or more slots in the plate are formed, each slot spaced from the sides of the plate is, with the feed point on an imaginary line through a Corner and the middle of the conductive Plate is arranged or matches with this, a first slot an elongated one body part which is adjacent and parallel to one of the first pages the plate is arranged, characterized in that the antenna of the Further includes a second slot, which is an elongated body part which is adjacent and parallel to the other of the first pages the plate is arranged, the first slot a corresponding one Fußschlitzabschnitt which is adjacent and parallel to a corresponding second side the plate is arranged, wherein the second slot has a corresponding Includes foot slot section, adjacent and parallel to the corresponding second sides the plate is arranged.

The antenna can resonate in a plurality of separate frequency bands. This means that the antenna is capable of multi-band operation without requiring additional resonant plates, shorting pins, matching circuits or several feeding points are needed.

Preferably the feed mechanism is designed to be the conductive plate provides a direct feed. The feeding mechanism can Alternatively, feed the plate by indirect coupling. Preferably the antenna is made up of microstrips.

Preferably At least a portion of at least one of the slots is in close proximity to an edge the plate arranged so that the at least one slot part electromagnetic Energy in a different frequency band than the natural one Resonance frequency bands the plate radiates.

Preferably At least one slot does not comprise a first and a second one parallel slot section. In particular, it is preferred that the first and second slot portions substantially perpendicular to each other are arranged. Furthermore, it is preferred that the at least one Slit essentially I-shaped or H-shaped.

at a preferred embodiment the conductive plate has a generally rectangular shape and includes a first and a second slot, one each on both sides of the feeding point, each slot having an elongated body portion with a respective foot section both ends of the body section or adjacent to them, the slots are designed so that the respective elongated ones Body sections in the Essentially parallel in relation to a pair of opposite Edges of the plate are arranged and that the respective foot sections In the next Close to opposite the other pair Plate edges are located. Preferably, this is a pair of opposed ones Plate edges from the plate edges, which during the resonance in a Frequency band emit electromagnetic energy, the conductive plate primarily designed for it is to resonate with respect to the frequency band. Preferably For example, the first and second slots are substantially I-shaped and the respective foot sections are designed so that they are essentially parallel to the others against liegenen Plate edges are arranged.

Other preferred characteristics are presented in the dependent claims.

Further Advantageous aspects of the invention will become apparent to those skilled in the art Review of the following description of the specific embodiments of the invention with reference to the accompanying drawings.

SHORT DESCRIPTION THE DRAWINGS

specific embodiments The invention will now be described by way of example and with reference to FIGS attached Drawings are described, wherein:

1 Fig. 12 is a perspective view of a planar antenna in position in a mobile telephone receiver;

2 Fig. 12 is a perspective view of a planar antenna according to the invention mounted on a front end module (FEM) for a radio transceiver;

3 a side view of the antenna 2 is;

4 is a plan view of an unslotted planar antenna;

5a to 5c Diagrams of the current density in the unslotted antenna 4 at different supply frequencies are;

6 is a plot of the reflection loss (dB) versus frequency (GHz) for the unslit planar antenna;

7 shows a set of equations for use in the construction of a planar antenna.

DETAILED DESCRIPTION OF THE INVENTION

With reference to 1 In the drawings, there is shown a perspective view of a mobile telecommunication handset generally used with 10 is designated. The listener 10 is shown in the general outline only for purposes of clarity. The listener 10 comprises a planar antenna in the preferred form of a microstrip planar antenna 12 , The flat antenna 12 is on a radio module or front-end module (FEM) 14 fastened, in turn, in a conventional manner on a printed circuit board (PCB) 16 is attached. The antenna 12 includes a dielectric substrate 20 that is a first conductive layer or plate 18 on one side and a second conductive layer or ground plane 22 on the opposite side. A feeding mechanism (in 1 not shown) is for communication between the FEM 14 and the antenna 12 provided. The feed mechanism may be directly connected to the plate (direct feed) or it may be indirectly coupled to the plate.

When used, the FEM will send and receive 14 as is customary about the antenna 12 elec magnetic signals, including radio frequency signals. During transmission, the FEM feeds 14 via the feed mechanism an electrical signal into the antenna 12 one. The signal excites the plate 18 to cause the emission of electromagnetic energy or waves thereof. In particular, a charge distribution on the back or bottom of the plate 18 and the ground plane generates when the plate 18 is excited by a supply signal. At some point, the bottom of the plate is positively charged and the ground plane is negatively charged. The attractive forces between these charges tend to hold a large percentage of the charge between the two opposing surfaces. However, the repulsive forces between positive charges on the plate push some of these charges towards the edges of the plate, resulting in a large charge density or current density at some of the edges (usually two opposite edges). These regions of high charge density are the source of fringing fields at the edges of the plate 18 and the corresponding radiation from the plate 18 ,

A Planar or flat antenna radiates energy only in frequency bands, in which resonance occurs. The location of the resonant or operational frequency band a flat antenna hangs mainly from their dimensions and their composition. If a plate is fed with a signal in the resonant frequency band Therefore, the disk emits energy in this frequency band.

The efficiency with which the disk emits energy depends, among other things, on whether an impedance match between the disk 18 and the feeding mechanism or not. Typically, a coaxial feed device has an impedance of 50 ohms, and it is therefore important to position the feed point so that the effective impedance applied by the board at the feed point matches the impedance of the feed device. Radiation efficiency can be measured in terms of reflectance loss (typically in decibels (dB)) or voltage standing wave ratio (VSWR). A reflection loss value (RLV) of about -10 dB or better, which corresponds to a VSWR of about 2 or less, is usually considered desirable in an operable frequency band, although poorer efficiency may be satisfactory.

Usually a flat antenna 12 considered as a single band construction with narrow bandwidth, ie a design with only a single relatively narrow resonant frequency band. To construct a flat antenna for operation in a desired frequency band and for a given dielectric constant and substrate thickness, equations [1] to [4] can be made 7 used to approximate the required length and width of the plate 18 to determine. Normally, fine tuning is then required to complete the plate dimensions to suit the application in question.

The next step in the construction of the flat antenna 12 is to determine the position of the point where the feed mechanism feeds the antenna. Conventionally, the feeding point is arranged on an imaginary straight line perpendicular to the edges of the plate 18 and passes through the middle of the plate. Such a feeding position will hereinafter be referred to as a central or symmetrical feeding position. One conventional way of determining the best position for the feed point is to operate the antenna 12 for different feed positions starting from a plate edge and towards the center of the plate along the imaginary center line. A suitable feed point is found when there is an impedance match between the feed mechanism and the plate (note that in some cases there is no impedance match on the center line.) In these cases, the normal solution is the size of the plate 18 or an impedance matching network between the feed mechanism and the disk 18 provide).

When a signal is fed into the resonant or operable frequency band, the current density on the surface of the plate increases 18 along two opposite edges of the plate 18 significantly, causing electromagnetic waves to be radiated from these edges. The current density also increases on the surface of the plate 18 between the two radiating edges, and this causes further electromagnetic radiation emanating from the gap between the two radiating edges. The resulting radiation pattern is relative to the plate 18 essentially symmetrical, and this optimizes the gain of the antenna. This is the main reason why flat antennas are traditionally fed from a central position.

However, a center fed flat antenna provides only a single resonant frequency band. Previous attempts have been made to provide multi-band planar antennas, including multi-band flat antennas. These attempts involve stacking or laminating two planar antennas on top of each other or side by side, or using an appropriate network. Other attempts included combining slots and shorting pins or providing multiple feed points. It is believed that such previous attempts have disadvantages in terms of size and / or complexity. Their manufacture can consequently be relatively difficult and expensive. In addition, it is believed that the size of these antennas makes them unsuitable for incorporation into modem telecommunications devices, particularly telephone handsets. The problem of size is exacerbated by the fact that many mobile telecommunication networks operate in relatively low frequency bands, where low frequency operation normally requires a large antenna.

As will now be described, one aspect of the invention provides a Single-Layer Planar or Flat Antenna capable of multi-band operation without the use of shorting pins, matching nets or more Dining items is able.

2 and 3 illustrate a flat antenna 112 , which is designed according to a preferred embodiment of the invention and on a FEM 114 is attached. The antenna 112 includes a multi-sided plate 118 in the form of a layer of conductive material, in particular conductive metal, such as copper or a copper alloy. The plate 118 Coats one side of a substrate 120 made of a dielectric material such as duroid, ceramic or alumina. A second conductive layer 122 Covers the opposite side of the dielectric substrate 120 , The second conductive layer 122 which are typically made of the same material as the plate 118 exists, serves as a ground plane for the antenna 112 ,

The antenna 112 includes a feeding mechanism 124 for supplying electromagnetic signals (such as radio or microwave signals) in the form of electrical signals between the antenna 112 and the FEM 14 , In 2 takes the feeding mechanism 124 the shape of a coaxial feeder, although it will be apparent to those skilled in the art, that other forms of conventional feeder mechanisms such as microstrip, stripline and waveguide may alternatively be used. The feeding device 124 is preferably designed to be a direct feed into the plate 118 provides and is accordingly at a feed point 126 on the plate 118 self-attached. A non-conductive shell 123 For example, formed of polytetrafluoroethylene (PTFE) surrounds the body of the feeder 124 ,

The feeding point 126 is on an imaginary straight line 128 passing through a corner of the plate 118 and the middle of the plate 118 runs. If the plate is a straight-sided figure, like the generally rectangular plate 118 that in the example off 2 is shown, is the feed point 126 on a diagonal of the plate.

When the feeding point 126 arranged on a diagonal, it is found that the plate 118 resonates in a variety of different frequency bands. It is believed that this phenomenon occurs because all sides of the disk are exposed to the excitation signal as possible areas from which radiation can emanate. In the case of the generally rectangular plate 118 out 2 are therefore due to the diagonally arranged feeding point 126 all four sides of the plate 118 available as potential radiating elements. Since the frequency at which radiation takes place depends on the plate dimensions, and since the corresponding opposite sides of the plate 118 have different lengths, the respective resonance states occur in different frequency bands.

The plate 118 includes two slots 130 . 132 for influencing the performance of the antenna 112 as described in more detail below.

First, consider the operation of an unslotted disk. 4 shows a plan view of an unslotted plate 218 with a diagonally arranged feeding point 226 is provided. The dimensions of the plate 218 are made using equations [1] to [4] 7 for a desired operating frequency, fr, of about 1800 MHz, wherein the substrate thickness, t, is about 1.2 mm and the dielectric constant, εr, is about 10. Accordingly, the length is 1 of the plate 218 about 34.20 mm and the plate width, w, is about 23.37 mm. The optimal position of the feeding point 226 was determined by the operation of the plate 218 was simulated, with the feed point first at or near a corner 234 the plate 218 and then subsequently at points progressively closer to the center of the plate along the diagonal. In the present design, an impedance match was found when feed point 226 was 5.70mm from the longer edge 236 the plate 218 and 7.98 min from the shorter edge 238 the plate 218 was arranged as in 4 shown. It is understood that the feeding point 226 as well along the corresponding diagonal from each corner of the plate 218 can be arranged.

In 5a to 5c is the current density on the plate 218 shown. It can be seen that only areas of relatively high or significant current density are shown by the dashed lines. In general, the current density on a plate may be in the range of 0 to 1500 A / m or higher. In 5 are only areas; where the current density about 400 A / m and more is shown. A current density of about 500 A / m and more is considered to be particularly significant.

5a to 5c show sketches of the current density on the plate 218 at different supply frequencies at which a resonance occurs. 5a to 5c therefore show the current density of the plate 218 in three different resonance states in three different frequency bands. In 5 is the current density by short dashes on the surface of the plate 218 displayed, wherein the density of the bars corresponds to the current density. 5a shows the current density when the plate 218 is fed with an excitation signal of about 1389 MHz. The main area of high current density is roughly the dashed line 501 displayed. This area corresponds to the area of the most significant electromagnetic radiation from the panel 218 in this resonant condition, where the radiation occurs in a frequency band centered at about 1389 MHz. How out 5a As can be seen, the main areas of high current density in this frequency band occur at the middle portions of the opposite longer edges 236 . 240 and around them as well as on the plate 218 between the two edges 236 . 240 on. Consequently, the main radiation of electromagnetic energy occurs at the middle portions of the edges 236 . 240 and around them and from the disk surface between the edges 236 . 240 in this resonant state (and therefore in the 1389 MHz frequency band).

A second resonant condition occurs when the excitation signal is about 1971 MHz, and the associated current density map is in 5b shown. The main area of high current density is roughly the dashed line 503 displayed. In this condition, the main areas of high current density are in the middle portions of the remaining two opposite edges 238 . 242 and around them as well as on the plate 218 between the two edges 238 . 242 , Consequently, the main radiation of electromagnetic energy in the frequency band around 1971 MHz occurs at the middle portions of the edges 238 . 242 around and around the board surface between the edges 238 . 242 on.

A third resonance condition occurs when the excitation signal is about 2476 MHz and the associated current density map is in 5c shown. The main area of high current density is roughly the dashed line 505 displayed. In this state, the main areas of high current density are in the middle portions of all four edges 236 . 238 . 240 . 242 and around them. Consequently, the main radiation of electromagnetic energy occurs in the frequency band around 2476 MHz at the four edges 236 . 238 . 240 . 242 and around it. It can also be seen that a zero point for the current density in the middle of the plate 218 and around it is present and that the level of current density towards the edges of the plate 318 increases. The current density or the radiation pattern, the or in 5c 2 is linearly or circularly polarized, which means that a high current density and therefore radiation occurs simultaneously at all four edges in this frequency band.

Out 5a to 5c it is apparent that the plate 218 as a result of the diagonal feeding position is able to energy from all four edges 236 . 238 . 240 . 242 unlike a conventional mid-feed plate, which emits energy only from two opposite edges. This allows the plate 218 resonates in more than one frequency band.

6 shows the reflection loss (dB) for each of the resonance states that occur in 5a to 5c are illustrated. The first reflection loss peak 601 represents a resonant or operable frequency band centered at about 1389 MHz and corresponding to the resonant state in 5a is shown. The second reflection loss peak 602 represents a resonant frequency band centered at about 1971 MHz and corresponding to the resonant state found in 5b is shown. The third reflection loss tip 603 represents a resonant frequency band centered at about 2476 MHz and corresponding to the resonant state found in 5c is shown. The second reflection loss peak 602 is significantly better (about -13 dB) than the first and third reflection loss peaks 601 . 603 (each about -4 dB and -4.5 dB). This is expected since the plate 218 specially designed for a resonance at around 1800 MHz and was the feed point 226 has been chosen to provide a good impedance match in this frequency range. Nevertheless, the first and third reflection loss peak 601 . 603 and, as described in more detail below, may be designed to provide additional operable frequency bands for an antenna in which they are integrated.

Therefore, the unslotted plate 218 be installed with diagonal feed in an antenna of the general kind, as in 2 and 3 and the resulting antenna is operable in a number of different frequency bands. This is achieved by using only a single conductive layer for the plate 218 , using only a single feed mechanism and without the need for shorting pins or matching circuitry. However, the relatively poor reflection loss peaks 601 . 603 for the first and third frequency band normally unsatisfactory for the commercial use. In addition, there are the three illustrated reflection loss peaks 601 . 602 . 603 in frequency bands that are not currently in commercial use in the mobile telecommunications industry. In this context, four main frequency bands currently in use in the mobile telecommunications market are GSM (Global System for Mobile telecommunications - about 890 to 960 MHz), GPS (Global Positioning System - about 1.57 to 1.58 GHz), DCS ( Digital Communication System - about 1.71 to 1.88 GHz) and Bluetooth (about 2.4 to 2.48 GHz).

It is therefore suggested to have one or more slots in the plate 218 to affect the performance of the antenna. In particular, it is proposed to provide a planar antenna capable of satisfactory operation in at least two commercially used frequency bands.

The Provision of slots increased the current density in the plate around at least some of the slot edges around. An increase in current density has the effect of having the plate becomes electrically larger, and this causes the disk to behave as if it were physically bigger, though the actual Length and Width of the plate are unchanged. By careful Arrangement of a slot (including the slot shape, the Slot size and the Slot position) can one or more of the frequency bands, in which the plate resonates to be adjusted. Especially For example, by arranging at least a portion of a slot in or adjacent to a region of the plate having a relatively high current density while has the resonance in a given frequency band, the frequency band (i.e., the resonance occurs at a lower frequency on). This is because the increase in the current density of the caused by the presence of the slot causes that the record behaves like this as if it were bigger - and larger plates generally resonate at lower frequencies.

The Slots also provide another effect when they according to the invention are arranged. The raised Surface current density around the slot edges causes additional reflection loss peaks in different frequency bands. The slot edges, when properly positioned, act as Pseudo plate edges from which electromagnetic energy is emitted can. One slot can therefore effectively have one or more others resonance states for the plate and thus increase the versatility of the antenna.

The Providing a slot in the plate can also be the affect effective impedance of the plate relative to the feed point. The slot may therefore be the size of the reflection loss tip in one or more resonant frequency bands.

Therefore can with a suitable construction and arrangement of slots according to the invention the natural Resonance frequency bands of a planar antenna, other resonant frequency bands, i. Operating frequencies, are generated and the reflection loss value (i.e., the disk efficiency) in the resonant frequency bands be improved. However, the elimination of material from a plate to form a slot disadvantageous to the Efficiency of the antenna effect, and this must during slot construction considered become.

Out From the foregoing, it can be seen that it is for the construction of a plate necessary for operation in a number of different frequency bands is, carefully to choose an arrangement of slots so that the plate in the desired frequency bands and with a satisfactory efficiency (i.e. a satisfactory Reflection loss value) resonates. More than one slot is preferred since this is the setting of a larger number of frequency bands relieved - to For example, a slot can be used to set the frequency value and / or reflection loss value primarily in a resonance frequency state to adjust while another slot for that can be used, the frequency value and / or reflection loss value primary in a different resonant frequency state.

For determining the location of one or more slots for adjusting one or more resonant frequencies, it has been found that attaching a slot (or portion of a slot) in or adjacent to a region of significant electromagnetic radiation in a particular resonant state will generally have the current density in the resonator Increased range, whereby the radiation frequency is reduced in this state. Increasing the length of the slot (or sub-slot) in the area also increases the current density and reduces the radiation frequency (and vice versa). The dislocation of the slot (or sub-slot) closer to a plate edge radiating in the resonant state also increases the current density around the slot (or sub-slot), thereby reducing the radiation frequency (and vice versa). Similarly, dislodging a slit (or slit) into or towards a higher radiance region (s) further increases current density and lowers the frequency. Furthermore, the slot (s) may cause additional resonance states which are not appreciable in an unslotted disc. This is special especially the case when the slot (s) (or sub-slot (s)) are located in close proximity to and substantially parallel to a plate edge.

It It can be seen that in a plate of different dimensions the resonance states from both a slotted and an unslotted plate in other frequency bands than can occur as described above and the slots on this Way in different frequency bands can act.

It It can be seen that the slot construction methods described herein can be applied to plates, not necessarily from a point on a diagonal be fed.

The Presence of more than one slot in the plate is preferred since this makes it easier to influence more than one operating frequency. However, it can be seen that an operable disk is also under Use of only one slot can be achieved.

It It will also be appreciated that the or each slot is not necessarily Must be I-shaped. However, it is preferred that at least one slot has a first one and a second non-parallel slot portion. This increases the length of the Slit edges in a given area (for example around the feet), whereby the effect that the slot has on the operating frequencies is enlarged. In particular, it is preferred that the first and second slot section essentially perpendicular to each other. This is special useful for general rectangular plates, since it is disposing of the slot with a corresponding section substantially parallel to a corresponding one Plate edge allows. For one non-rectangular plate can be the relative angle between the set according to the first and the second slot section become. It will be apparent to those skilled in the art that there are many different slot shapes there are that can be used to take advantage of the teachings of the invention. For example, the foot sections of the slot is not necessarily located at the very end of the body portion be.

Of the second non-parallel slot section does not necessarily need one piece to be with the first slot section. For example, the foot sections at an I-shaped Slit from the body section be separated. this leads to to a decrease in the current density, especially in the range between the foot sections and the body part. The reduction in current density leads to an increase in the operating frequency in the resonance states, in which the main radiation areas are the area around the foot sections encompass around. It has also been found that a Separation of the feet from the body Reflection loss value improved in the DCS frequency band.

It is also possible omit the second slot section. For example, the foot sections an I-shaped one Slot be omitted. This leads to a decrease in the current density in the areas where the feet were, what in turn leads to an increase in the operating frequency in the resonance states, in which the main radiation areas the area around the foot sections include.

A Another alternative is at least part of the body section to omit the slot. For example, with an I-shaped slot the middle section of the slot body are removed so that two spaced T-shaped slots remain. This arrangement is in the cases suitable in which the plate for an operation in frequency bands is determined, in which the middle portions of the slots no significant Role-play.

It is generally desirable that an antenna generates as symmetrical a radiation pattern as possible, and it is therefore preferred that the slots are generally one symmetrical shape and generally a symmetrical arrangement in the plate.

It It is also apparent that the invention is not limited to use limited with antennas is where the plate is fed directly with an excitation signal becomes. Other conventional food arrangements, such as coupling, a coplanar waveguide or microstrip feedline, can also be used. In any case, the feeding point according to the invention is the same arranged that he is on an imaginary line from a corner the plate is to the center of the plate or matches this.

It can be seen that the plate 118 . 218 Can both transmit and receive signals in multiple frequency bands. Preferably, the plate is 218 of the invention mounted on a front-end module (FEM), which is designed both for transmitting and for receiving signals in the corresponding frequency bands. However, the plate can 218 alternatively be used with a FEM that can only receive or only send.

It is also noted that the plates 118 . 218 can resonate in other frequency bands in addition to those described herein. For example, in 6 a little reflection loss tip 604 at about 2750 MHz available. However, such additional reflection loss tips are not used by the preferred embodiment of the invention.

Claims (8)

Flat antenna ( 12 ), comprising: a generally rectangular conductive plate ( 118 ) defined by first and second pairs of opposite sides; a ground plane ( 122 ); a dielectric substrate ( 120 ) between the plate and the ground plane; a feed mechanism ( 124 ) for applying electromagnetic signals to a feed point ( 126 . 226 ) located on the conductive plate; and one or more slots ( 130 . 132 ) formed in the plate, each slot being spaced from the sides of the plate, the feed point (Fig. 126 . 226 ) is arranged on or coincides with an imaginary line through a corner and the center of the conductive plate, a first slot comprising an elongated body portion disposed adjacent and parallel to one of the first sides of the plate, characterized in that the antenna of the Another second slot ( 132 ) comprising an elongated body portion disposed adjacent and parallel to the other of the first sides of the plate, the first slot (Fig. 130 ) includes a corresponding foot slot portion disposed adjacent and parallel to a corresponding second side of the disk, the second slot (14) 132 ) includes a corresponding foot slot portion disposed adjacent and parallel to the respective second sides of the plate. An antenna according to claim 1, wherein the foot slot sections one piece with the corresponding elongated body parts each of the first and second slots are formed. An antenna as claimed in any one of the preceding claims, wherein the sides of the first pair are shorter than the sides (Fig. 240 . 246 ) of the second pair. Antenna according to one of the preceding claims, wherein the feed mechanism ( 124 ) is arranged to provide a direct feed to the conductive plate. Antenna according to one of the preceding claims, wherein the antenna is formed from a microstrip. Antenna according to one of the preceding claims, wherein the first and second slots are substantially "H" shaped are. An antenna according to any one of the preceding claims, wherein the first and second slots ( 130 . 132 ) on both sides of the feed point ( 124 Each slot has an elongated body portion with a corresponding foot portion at or adjacent both ends of the body portion, the respective elongate body portions being disposed substantially parallel with respect to a respective pair of first opposing sides of the panel and adjacent the respective foot portions are arranged to the second pair of opposite plate sides. The antenna of claim 1, wherein the first pair is opposed Plate sides are the plate sides which are in resonance during resonance Frequency band emit electromagnetic energy, the conductive plate primary designed for it is to resonate with respect to the frequency band.