HK1097354B - Circuit board having a peripheral antenna apparatus with selectable antenna elements - Google Patents

Description

Circuit board including peripheral antenna device with selectable antenna elements

Cross Reference to Related Applications

The priority of U.S. provisional patent application No. 60/630,499, entitled "Method and Apparatus for providing 360 Degrid Coverage via Multiple Antenna Elements Co-located with electronic Circuitry on a Printed Circuit Board Assembly", filed on 22.2004, is hereby incorporated by reference. This application also relates to co-pending U.S. patent application No. 11/010,076 entitled "System and Method for an Omnidirectional planar antenna Apparatus with selected Elements", filed on 9.2004, also incorporated herein by reference.

Technical Field

The present invention relates generally to wireless communications, and in particular to a circuit board including a peripheral antenna arrangement with selectable antenna elements.

Background

In communication systems, there is a continuing increased demand for higher data throughput and a corresponding drive to reduce interference that can disrupt data communications. For example, in an IEEE 802.11 network, an access point (i.e., base station) communicates data with one or more remote receiving nodes (e.g., network interface cards) via a wireless link. The wireless link may be susceptible to interference from other access points, other radio transmission devices, changes or disturbances in the wireless link environment between the access point and the remote receiving node, and the like. The interference may be such as to degrade the wireless link, for example by forcing communication at a lower data rate, or may be strong enough to completely disrupt the wireless link.

One approach to reducing interference in the wireless link between the access point and the remote receiving node is to provide omni-directional antennas at the access point according to the "diversity" law. For example, one common configuration for the access point includes a data source coupled to two or more physically separated omnidirectional antennas through a switching network. The access point may select one of the omni-directional antennas by which to maintain the wireless link. Due to the separation between the omni-directional antennas, each antenna experiences a different signal environment and each antenna contributes a different interference level to the wireless link. The switching network couples the data source to any of the omnidirectional antennas that experiences the lowest interference within the wireless link.

However, one limitation to utilizing two or more omni-directional antennas for an access point is that each omni-directional antenna includes a separate manufacturing unit for the access point, thus requiring additional manufacturing steps to be incorporated into the omni-directional access point. A further limitation is that omni-directional antennas typically include a standing bar (wand) attached to the housing of the access point. The wand typically includes a stem that is exposed to the exterior of the housing and may be susceptible to breakage or damage.

Another limitation is that typical omni-directional antennas are vertically polarized. Vertically polarized Radio Frequency (RF) energy does not travel as efficiently as horizontally polarized RF energy in a typical office or residential space, and furthermore, most laptop network interface cards have horizontally polarized antennas. To date, typical solutions for producing horizontally polarized RF antennas have been either too costly to manufacture or have not provided sufficient RF performance to be commercially viable.

Yet another limitation with two or more omni-directional antennas is that each of several antennas may experience similar levels of interference because the physically separated antennas may still be relatively close to each other, and only a relatively slight reduction in interference may be obtained by switching from an omni-directional antenna to another omni-directional antenna.

Disclosure of Invention

A system includes communication circuitry, a first antenna element, and a second antenna element. The communication circuit is located on a first area of a circuit board and is configured to generate an RF signal to an antenna feed port of the circuit board. The first antenna element is located near a first periphery of the circuit board and is configured to generate a first directional radiation pattern when coupled to the antenna feed port. The second antenna element is located near a second periphery of the circuit board and is configured to generate a second directional radiation pattern offset from the first directional radiation pattern when coupled to the antenna feed port.

A method includes generating an RF signal in a communication circuit located on a first area of a circuit board, routing the RF signal from the communication circuit to an antenna feed port of the circuit board; and coupling the RF signal from the antenna feed port to the first antenna element and the second antenna element. The first antenna element is located near a first periphery of the circuit board and is configured to generate a first directional radiation pattern when coupled to the antenna feed port. The second antenna element is located near a second periphery of the circuit board and is configured to generate a second directional radiation pattern offset from the first directional radiation pattern when coupled to the antenna feed port.

A circuit board includes: an antenna feed port configured to distribute RF signals generated by communication circuitry located on the circuit board; a first antenna element located proximate a first periphery of the circuit board and configured to generate a first directional radiation pattern when coupled to the RF signal; and a second antenna element located proximate a second periphery of the circuit board and configured to generate a second directional radiation pattern offset from the first directional radiation pattern when coupled to the RF signal.

Drawings

The present invention will now be described with reference to the accompanying drawings, which represent preferred embodiments of the invention. In the drawings, like elements have the same reference numerals. The particular embodiments are illustrative of the invention and not limiting thereof. The drawings include the following figures:

FIG. 1 illustrates an exemplary diagram of a system including a circuit board including a peripheral antenna device having selectable elements in accordance with a specific embodiment of the present invention;

FIG. 2 illustrates the circuit board of FIG. 1 including a peripheral antenna assembly having selectable elements in accordance with a specific embodiment of the present invention;

fig. 3A illustrates a modified dipole (dipole) for the antenna apparatus of fig. 2, in accordance with a specific embodiment of the present invention;

fig. 3B illustrates a reduced-size modified dipole for the antenna apparatus of fig. 2, according to an alternative specific embodiment of the invention.

Fig. 3C illustrates an alternative modified dipole for the antenna apparatus of fig. 2, according to an alternative specific embodiment of the present invention.

Fig. 3D illustrates a modified dipole with coplanar band switching for the antenna apparatus of fig. 2, according to an alternative specific embodiment of the present invention.

FIG. 4 illustrates the antenna element of FIG. 3A showing layers of a circuit board in accordance with one embodiment of the present invention;

fig. 5A illustrates the antenna feed port and switching network of fig. 2 in accordance with one embodiment of the present invention;

fig. 5B illustrates the antenna feed port and switching network of fig. 2 in accordance with an alternative embodiment of the present invention;

fig. 5C illustrates the antenna feed port and switching network of fig. 2 in an alternative embodiment according to the present invention.

The main reference numbers are described below:

100: system for controlling a power supply

105: circuit board

110: peripheral antenna device

120: radio modem

210: region(s)

215: power supply

220: antenna selector

225: data processor

230: radio modem

234: microstrip RF line

235A-C: antenna feed port

237: switching network

239A-G: microstrip feeder line

240A-G: antenna element

310: first dipole member

311: second dipole member

312: reflector

315: first dipole member

316: second dipole member

317: reflector

321: first dipole member

322: second dipole member

323: reflector

330A-B: CPS dipole arm

331: reflector

332: coplanar band (CPS) conversion

411D: second dipole member

412A-D: reflector portion

415: metallized via

515A-G: RF trace

520A-G: PIN diode

Detailed Description

A system for wireless link (i.e., radio frequency or RF) to a remote receiving device includes a circuit board containing communication circuitry for generating RF signals and an antenna device for transmitting and/or receiving the RF signals. The antenna device comprises two or more antenna elements arranged close to the periphery of the circuit board. Each antenna element provides a directional radiation pattern. In some embodiments, the antenna elements are electronically selectable (e.g., switched on or off) to enable the antenna assembly to form a configurable radiation pattern. If multiple antenna elements are switched on, the antenna device can form an omnidirectional radiation pattern.

Advantageously, the circuit board interconnects the communication circuits and the antenna arrangement is provided in a printed circuit board which can be easily manufactured. Incorporating the antenna device within the printed circuit board may reduce the cost of manufacturing the circuit board and simplify the interconnectivity with the communication circuit. Additionally, incorporating the antenna device within the circuit board may provide more consistent RF matching between the communication circuitry and each antenna element. A further advantage is that the antenna device radiates a directional radiation pattern substantially in the plane of the antenna elements. When horizontally assembled, the radiation patterns are horizontally polarized, and thus RF signal transmission in a room can be enhanced compared to a vertically polarized antenna.

Fig. 1 illustrates an exemplary schematic diagram of a system 100 incorporating a circuit board including a peripheral antenna arrangement with selectable elements in accordance with an embodiment of the present invention. The system 100 may include, for example, but not limited to, a transmitter/receiver such as an 802.11 access point, an 802.11 receiver, a set-top box, a laptop computer, a television, a cellular telephone, a cordless telephone, a wireless VoIP phone, a remote control, and a remote terminal such as a handheld gaming device. In some embodiments, the system 100 includes an access point for communicating to one or more remote receiving nodes over a wireless link, such as an 802.11 wireless network.

The system 100 includes a circuit board 105 that contains a radio modulator/demodulator (modem) 120 and a peripheral antenna device 110. The modem 120 may receive data from a router connected to the internet (not shown), convert the data to a modulated RF signal, and the antenna device 110 may wirelessly transmit the modulated RF signal to one or more remote receiving nodes (not shown). The system 100 may also form part of a wireless local area network by communicating between a number of remote receiving nodes. While the present disclosure will focus on a particular embodiment of the system 100 that includes the circuit board 105, the various features of the present invention are applicable to a wide variety of applications and are not limited to the disclosed embodiments. For example, although the system 100 is described as transmitting to a remote receiving node via the antenna apparatus 110, the system 100 may also receive RF modulated data from the remote receiving node via the antenna apparatus 110.

Fig. 2 illustrates the circuit board 105 of fig. 1 including a peripheral antenna assembly 110 having selectable elements in accordance with an embodiment of the present invention. In some embodiments, the circuit board 105 comprises a Printed Circuit Board (PCB), such as FR4, Roger 4003, or other dielectric materials having four layers, although any number of layers, such as six, are contemplated.

The circuit board 105 includes a region 210 for interconnecting circuitry, including, for example, a power supply 215, an antenna selector 220, a data processor 225, and a radio modulator/demodulator (modem) 230. In some embodiments, the data processor 225 includes known circuitry for receiving data packets from a router connected to the internet (e.g., via a local area network). The radio modem 230 includes communication circuitry including substantially any device for converting data packets processed by the data processor 225 into modulated RF signals for transmission to and reception from one or more remote receiving nodes. In some embodiments, the radio modem 230 includes circuitry for converting data packets into modulated RF signals corresponding to 802.11.

From the radio modem 230, the circuit board 105 also includes a microstrip RF line 234 to route the modulated RF signals to an antenna feed port 235. Although not shown, in some embodiments, the antenna feed port 235 is configured to distribute the modulated RF signal directly to the antenna elements 240A-240G of the peripheral antenna device 110 via respective antenna feeds. In the embodiment depicted in fig. 2, the antenna feed port 235 is configured to distribute the modulated RF signal to one or more of the selectable antenna elements 240A-240G via the switching network 237 and microstrip feed lines 239A-G. Although depicted as microstrips, the feed line 239 may also include coupling microstrips, coplanar strips with impedance transformers, coplanar waveguides, coupling strips, and the like.

The antenna feed port 235, the switching network 237 and feed line 239 include respective switching and routing components on the circuit board 105 for routing the modulated RF signal to the antenna elements 240A-G. That is, the antenna feed port 235, the switching network 237, and feed 239 include structure for impedance matching between the radio modem 230 and antenna elements 240, as further described herein. The antenna feed port 235, the switching network 237 and the feed 239 may be further illustrated in fig. 5.

That is, the peripheral antenna assembly includes a plurality of antenna elements 240A-G located proximate to the peripheral region of the circuit board 105, as described further herein. The antenna elements 240 each produce a directional radiation pattern having gain (as compared to an omni-directional antenna) and polarization substantially in the plane of the circuit board 105. The antenna elements may each be aligned in a direction that is offset from the other antenna elements 240, such that the directional radiation pattern produced by an antenna element (e.g., the antenna element 240A) is offset in direction from the directional radiation pattern produced by another antenna element (e.g., the antenna element 240C). Some of the antenna elements may also be arranged in substantially the same direction, such as antenna elements 240D and 240E. Arranging two or more antenna elements 240 in the same direction may provide spatial diversity between the antenna elements 240 arranged in this manner.

In embodiments having the switching network 237, various combinations of the antenna elements 240 are selected to produce various radiation patterns from highly directional to omnidirectional. Generally, enabling adjacent antenna elements 240 may result in higher directivity in azimuth than selecting either antenna element 240 alone. For example, selecting adjacent antenna elements 240A and 240B may provide higher directivity than selecting either of the individual antenna elements 240A or 240B. Alternatively, selecting one antenna element (i.e., such as antenna elements 240A, 240C, 240E, and 240G) or all of the antenna elements 240 every other may produce an omnidirectional radiation pattern.

For a further understanding of the principles of operation of the Selectable Antenna element 240, reference is made to co-pending U.S. patent application No. 11/010,076, filed on 9.12.2004, entitled "System and Method for and for an organic Planar Antenna Apparatus with selective Elements", and previously incorporated herein by reference.

Fig. 3A illustrates the antenna element 240A of fig. 2 in an embodiment in accordance with the invention. The antenna element 240A of this particular embodiment comprises a modified dipole having components on both exterior surfaces of the circuit board 105 (which may be considered the planes of fig. 3A). In detail, on the first surface of the circuit board 105, the antenna element 240A includes a first dipole component 310. On a second surface of the circuit board 105, i.e., as illustrated by the dashed lines in fig. 3, the antenna element 240A includes a second dipole component 311 that extends substantially opposite the first dipole component 310. The first dipole component 310 and the second dipole component 311 form the antenna element 240A to produce a generally cardioid directional radiation pattern substantially in the plane of the circuit board.

In some embodiments, the dipole component 310 and/or the dipole component 311 may be bent to conform to the edge of the circuit board 105, such as the antenna elements 240B and 240C of fig. 2. Incorporating the bend into the dipole component 310 and/or the dipole component 311 reduces the size of the circuit board 105. Although described as being formed on a surface of the circuit board 105, in some embodiments, the dipole components 310 and 311 may be formed on an interior layer of the circuit board, as described herein.

The antenna element 240A may optionally include one or more reflectors (i.e., as the reflector 312). The reflector 312 includes elements that are configured to concentrate the directional radiation pattern formed by the first dipole component 310 and the second dipole component 311. The reflector 312 may also be configured to broaden the frequency response of the antenna element 240A. In some embodiments, the reflector 312 may broaden the frequency response of each modified dipole to about 300MHz to 500 MHz. In some embodiments, the combined operating bandwidth of the antenna device resulting from coupling more than one antenna element 240 to the antenna feed port 235 is less than the bandwidth resulting from coupling only one of the antenna elements 240 to the antenna feed port 235. For example, four antenna elements 240 (e.g., antenna elements 240A, 240C, 240E, and 240G) are selected to obtain an omni-directional radiation pattern, and the combined frequency response of the antenna device is approximately 90 MHz. In some embodiments, coupling more than one antenna element 240 to the antenna feed port 235 maintains matching with less than 10dB return loss at 802.11 wireless LAN frequencies, regardless of the number of switched-on antenna elements 240.

Fig. 3B illustrates the antenna element 240A of fig. 2 in an alternative embodiment according to the present invention. The antenna element 240A of this embodiment may be reduced in dimension compared to the antenna element 240A of fig. 3A. In detail, the antenna element 240A of the present embodiment includes a first dipole member 315 that merges into meanders (meanders), a second dipole member 316 that merges into corresponding meanders, and a reflector 317. Due to the meandering, the antenna element 240A of this embodiment may require less space on the circuit board 105 than the antenna element 240A of fig. 3A.

Fig. 3C illustrates the antenna element 240A of fig. 2 in an alternative embodiment according to the present invention. The antenna element 240A of this particular embodiment includes one or more components on one or more layers within the circuit board 105. In particular, in an embodiment, the first dipole component 321 is formed on an internal ground plane of the circuit board 105. A second dipole element 322 is formed on the outer surface of the circuit board 105. As further set forth with reference to fig. 4, the reflector 323 may be formed inside the circuit board 105 or may be formed on an exterior surface of the circuit board 105. One advantage of this embodiment of the antenna element 240A is that the path through the circuit board 105 is reduced or eliminated, resulting in a lower cost of manufacture for the antenna element 240A of this embodiment.

Fig. 3D illustrates the antenna element 240A of fig. 2 in an alternative embodiment according to the present invention. Antenna element 240A of this embodiment comprises a modified dipole having a microstrip-to-coplanar strip (CPS) transition 332 and CPS dipole arms 330A and 330B on a surface layer of circuit board 105. In particular, the present embodiment provides that the CPS dipole arm 330A may be coplanar with the CPS dipole arm 330B and may be formed on the same surface of the circuit board 105. This embodiment may also include a reflector 331 formed on one or more internal layers of the circuit board 105 or on an opposing surface of the circuit board 105. One advantage of this embodiment is that no vias are required within the circuit board 105.

It should be appreciated that the dimensions of the individual components of the antenna elements 240A-G, such as the first dipole component 310, the second dipole component 311 and the reflector 312, are dependent upon the desired operating frequency of the antenna device. In addition, it should be appreciated that the wavelength dimension is dependent upon the conductive and dielectric materials comprising the circuit board 105, since the speed of electron propagation is dependent upon the properties of the circuit board 105 materials. Thus, the wavelength dimensions referred to herein are specifically intended to incorporate into the properties of the circuit board, including considerations such as the conductive and dielectric properties of the circuit board 105. RF simulation software, such as IE3D from ZelandSoftware, Fremont, ca, may be utilized to establish the dimensions of the individual elements.

Fig. 4 illustrates the antenna element 240A of fig. 3A showing the layers of the circuit board 105 in an embodiment of the present invention. The circuit board 105 of this embodiment includes a 60 mil thick stack (stackup) having three dielectrics and four metallization layers a-D with an internal RF ground plane at layer B (10 mils from the top layer a to the internal ground layer B. layer B is separated from the next layer C, which may include a power plane, by a 40 mil thick dielectric.layer C is separated from the bottom layer D by a 10 mil dielectric.

The first dipole component 310 and portions 412A of the reflector 312 are formed on the first (outer) surface layer a. Respective corresponding portions 412B of the reflector 312 are formed in a second metallization layer B that includes connections (depicted as open traces) to the ground plane. On the third metallization layer C, respective corresponding portions 412C of the reflector 312 are formed. The second dipole component 411D is formed on the fourth (outer) surface metallization layer D together with a reflector corresponding portion 412D. Each reflector 412A-D and each second dipole component 411B-D on different layers is interconnected to the ground layer B by an array of metallized vias 415 (only one via 415 is depicted for simplicity) spaced less than 1/20 wavelengths apart, determined by the 2.4-2.5GHz operating RF frequency range of 802.11. Those skilled in the art will appreciate that the reflector 312 includes four layers, depicted as 412A-D.

One advantage of the antenna element 240A of fig. 4 is that transitions in the RF path can be avoided. In addition, the antenna element 240A of this embodiment provides a good ground plane for the ground dipole 311 and the reflector element 312 due to the via array interconnecting the layers of the circuit board 105 and the cut-away portions of the reflector 412A.

Fig. 5A illustrates the antenna feed port 235 and the switching network 237 of fig. 2 in an embodiment thereof according to the invention. The antenna feed port 235 of this embodiment receives the RF line 234 from the radio modem 230 into a distribution point 235A. From the distribution point 235A, impedance-matched RF traces 515A-G extend to PIN diodes 520A-G. In particular embodiments, RF traces 515A-G contain 20 mil wide traces based on 10 mil dielectric from the internal ground plane (i.e., ground plane B of fig. 4). Feed lines 239A-G (only a portion of feed line 239 is drawn for simplicity of illustration) extend from respective PIN diodes 520A-G to each antenna element 240.

Each PIN diode 520 includes a single pole, single throw switch to switch each antenna element 240 on or off (i.e., to couple or decouple each antenna element 240 from the antenna feed port 235). In a specific embodiment, a series of control signals (not shown) are utilized to bias each PIN diode 520. By forward biasing the PIN diode 520 and conducting DC current, the PIN diode 520 is switched on and the corresponding antenna element 240 is selected. The PIN diode 520 is reverse biased and the PIN diode 520 is switched off.

In a particular embodiment, the RF traces 515A-G have lengths equal to multiples of half a wavelength from the antenna feed port 235. Although depicted as equal lengths in fig. 5A, the RF traces 515A-G may be of unequal lengths, but multiples of half a wavelength from the antenna feed port 235. For example, the RF trace 515A may be zero in length, thus attaching the PIN diode 520A directly to the antenna feed port 235. The RF trace 515B may be a half wavelength, the RF trace 515C may be one wavelength, and so on, in any combination. PIN diodes 520A-G are multiples of half a wavelength from the antenna feed port 235, so disabling one PIN diode (e.g., PIN diode 520A) does not create RF mismatch that causes RF reflection back to the other enabled trace 515 (e.g., trace 515B) and the distribution point 235A. In this manner, when the PIN diode 540A is "off," the radio modem 230 sees a high impedance on the RF trace 515A, while the impedance of the "on" trace 515B is substantially unaffected by the PIN diode 540A. In some embodiments, PIN diodes 520A-G are located at a distance offset by a half wavelength. The offset is determined to take into account stray electrical content within the dispense point 235A and/or PIN diodes 520A-G.

Fig. 5B illustrates the antenna feed port 235 and the switching network 237 of fig. 2 in an alternative embodiment thereof in accordance with the present invention. The antenna feed port 235 of this embodiment receives the RF line 234 from the radio modem 230 into the distribution point 235B. The distribution point 235B of this particular embodiment is configured as a pad for the PIN diodes 520A-G. PIN diodes 520A-G are soldered between the distribution point 235B and the ends of feed lines 239A-G. Basically, the distribution point 235B of this embodiment represents a zero wavelength distance from the antenna feed port 235. One advantage is that the feed lines extending from the PIN diodes 520A-G to the antenna elements 240A-G provide a controlled impedance that is uninterrupted.

Fig. 5C illustrates the antenna feed port and switching network of fig. 2 in an alternative embodiment thereof in accordance with the present invention. This embodiment may be considered a combination of the embodiments described in fig. 5A and 5B. PIN diodes 520A, 520C, 520E, and 520G are connected to RF traces 515A, 515C, 515E, and 515G, respectively, in a manner similar to that previously described with reference to fig. 5A. However, PIN diodes 520B, 520D, and 520F are soldered to distribution point 235C and corresponding feed lines 239B, 239D, and 239F in a manner similar to that previously described with reference to fig. 5B.

Although the switching network 237 is described as including a PIN diode 520, it should be understood that the switching network 237 may include substantially any RF switching device such as a GaAs FET, as is well known in the art. In some embodiments, the switching network 237 includes one or more single pole, multi-throw switches. In some embodiments, one or more light emitting diodes (not shown) are coupled to the switching network 237 or feed line 239 as a visual indicator of which antenna element 240 is on or off. In some embodiments, a light emitting diode is placed in circuit with each PIN diode 520 such that the light emitting diode is illuminated when the corresponding antenna element 240 is selected.

Referring to fig. 2, the length of antenna feed 239 may not be equal from the antenna feed port 235, since in some embodiments the antenna feed port 235 is not at the center of the circuit board 105, which may result in equal length and minimal loss of antenna feed 239. The unequal lengths of the antenna feed lines 239 may cause phase shifts between the antenna elements 240. Thus, in some embodiments not depicted in fig. 2, the feed lines 239 to the antenna elements 240 are designed to be as long as the longest of the feed lines 239, even for those antenna elements 240 that are relatively close to the antenna feed port 235. In some embodiments, the length of the feed line 239 is designed to be a multiple of a half-wavelength offset from the longest of the feed lines 239. In yet other embodiments, the length of the feed line 239 is an odd multiple of the half-wavelength offset from the other feed lines 239, incorporating the "phase-reversed" antenna element 240 to compensate. For example, referring to fig. 2, antenna elements 240C and 240F are inverted 180 degrees because feed lines 239C and 239F are 180 degrees out of phase from feed lines 239A, 239B, 239D, 239E and 239G. In the phase-inverted antenna element 240, the first dipole component (e.g., a surface layer) replaces the second dipole component (e.g., a ground layer). It will be appreciated that this may provide a 180 degree phase shift within the antenna element to compensate for a 180 degree feeder phase shift.

The system 100 (fig. 1) incorporates a circuit board 105 (fig. 2) including a peripheral antenna arrangement with selectable antenna elements 240, which has the advantage that each antenna element 240 can be built directly on the circuit board 105, so that the entire circuit board 105 can be manufactured easily and at low cost. That is, as illustrated in FIG. 2, embodiments or layouts of the circuit board 105 include a substantially square or rectangular shape, thereby facilitating the panelization of the circuit board 105 from readily available circuit board materials. That is, the circuit board 105 minimizes or eliminates the possibility of damage to the antenna elements 240, as compared to systems incorporating externally mounted, vertically polarized "whip" antennas for diversity.

Another advantage of the circuit board 105 incorporating a peripheral antenna assembly with selectable antenna elements 240 is that the antenna elements 240 may be configured to reduce interference in the wireless link between the system 100 and a remote receiving node. For example, the system 100 communicating over a wireless link to the remote receiving node may select a particular configuration of the selected antenna element 240, which may minimize interference over the wireless link. For example, if an interfering signal is strongly received by the antenna element 240C and a remote receiving node is strongly received by the antenna element 240A, selecting only the antenna element 240A may reduce the interfering signal relative to selecting the antenna element 240C. The system 100 may select a configuration of the selected antenna element 240 that corresponds to a maximum gain between the system and the remote receiving node. Alternatively, the system 100 may select a configuration corresponding to selected antenna elements 240 that are below the maximum gain but that correspond to reduced interference. Alternatively, each antenna element 240 may be selected to form a combined omnidirectional radiation pattern.

Another advantage of the circuit board 105 is that the directional radiation pattern of the antenna element 240 is largely in the plane of the circuit board 105. When the circuit board 105 is horizontally mounted, the corresponding radiation pattern of the antenna element 240 is horizontally polarized. Horizontally polarized RF energy tends to propagate better indoors than vertically polarized RF energy. Providing horizontally polarized signals may improve interference rejection (potentially up to 20dB) from utilizing RF sources that use commonly available vertically polarized antennas.

The invention has been described in terms of several preferred embodiments. Other embodiments of the invention, including alternatives, modifications, permutations and equivalents of the embodiments described herein, will be apparent to those skilled in the art from consideration of the specification, review of the drawings and practice of the invention. The above-described embodiments and preferred features should be considered illustrative, and the invention is defined by the appended claims, which are therefore intended to include all such alternatives, modifications, permutations and equivalents as fall within the true spirit and scope of the invention.

Claims (29)

1. A peripheral antenna system comprising:

a communication circuit located in an interior region of a circuit board, the communication circuit configured to generate an RF signal to a feed line distribution point of the circuit board;

a first antenna element located proximate a first periphery of the circuit board, the first antenna element configured to produce a first directional radiation pattern when coupled to the feed line distribution point;

a second antenna element located proximate a second periphery of the circuit board, the second antenna element configured to produce a second directional radiation pattern offset from the first directional radiation pattern when coupled to the feed line distribution point, wherein the first antenna element and the second antenna element collectively produce omnidirectional and horizontally polarized radiation coverage in the plane of the circuit board when the first antenna element and the second antenna element are coupled to the feed line distribution point; and

a switching network configured to selectively couple the feeder distribution point to the first antenna element and the second antenna element,

wherein the switching network comprises a first RF switch located at a multiple of half a wavelength from the feeder distribution point, the first RF switch configured to selectively couple the feeder distribution point to the first antenna element.

2. The peripheral antenna system of claim 1, further comprising:

a first feed line of the circuit board configured to couple the feed line distribution point to the first antenna element; and

a second feed line of the circuit board configured to couple the feed line distribution point to the second antenna element, the second feed line having an electrical length that is a multiple of a half wavelength compared to the first feed line.

3. A peripheral antenna system as recited in claim 1, wherein the first antenna element comprises a modified dipole.

4. A peripheral antenna system according to claim 3, wherein the modified dipole comprises a bent dipole component.

5. A peripheral antenna system according to claim 3, wherein the first antenna element further comprises a reflector configured to focus the radiation pattern of the first antenna element.

6. A peripheral antenna system according to claim 3, wherein the first antenna element further comprises a reflector configured to broaden the frequency response of the first antenna element.

7. The peripheral antenna system of claim 1, wherein the first antenna element comprises a first dipole component and a second dipole component, wherein at least one of the first dipole component and the second dipole component is formed on an exterior surface of the circuit board.

8. A peripheral antenna system as recited in claim 1, wherein the first antenna element includes a first dipole component formed on a surface of the circuit board and a second dipole component formed on an opposite surface of the circuit board, the second dipole component being coupled to an internal ground layer of the circuit board.

9. A peripheral antenna system comprising:

a communication circuit located in an interior region of a circuit board, the communication circuit configured to generate an RF signal to a feeder distribution point of the circuit board;

a plurality of antenna elements disposed proximate to at least two edges of the circuit board, each of the plurality of antenna elements configured to form a directional radiation pattern when coupled to the feed line distribution point; and

a switching network configured to selectively couple the feeder distribution point to each of the plurality of antenna elements to collectively implement configurable and omnidirectional and horizontally polarized radiation patterns generated in the circuit board plane,

wherein the switching network comprises an RF switch for each antenna element, the RF switch being located at a multiple of half a wavelength from the feeder distribution point.

10. A peripheral antenna system according to claim 9, further comprising a feed line coupling the RF switch to the antenna element, the feed line having an electrical length that is a multiple of half a wavelength from a feed line point of divergence.

11. The peripheral antenna system of claim 9, wherein at least one of the antenna elements comprises a modified dipole.

12. The peripheral antenna system of claim 11, further comprising at least one phase-inverted modified dipole.

13. A peripheral antenna system according to claim 11, further comprising a reflector for the modified dipole, the reflector configured to focus a radiation pattern of the modified dipole.

14. A peripheral antenna system according to claim 11, further comprising a reflector for the modified dipole, the reflector configured to broaden the frequency response of the modified dipole.

15. A method for generating a radiation pattern, comprising:

generating an RF signal in a communication circuit located in an interior region of a circuit board;

a feeder line distribution point for conveying the RF signal from the communication circuit to the circuit board; and

coupling the RF signal from the feeder distribution point to a first antenna element and a second antenna element, the first antenna element located proximate a first periphery of the circuit board, the second antenna element located proximate a second periphery of the circuit board, the first antenna element configured to produce a first directional radiation pattern when coupled to the feeder distribution point, the second antenna element configured to produce a second directional radiation pattern offset from the first radiation pattern when coupled to the feeder distribution point, wherein the first directional radiation pattern and the second directional radiation pattern collectively produce an omnidirectional and a horizontally polarized radiation pattern in a plane of the circuit board when the first antenna element and the second antenna element are coupled to the feeder distribution point,

wherein coupling the RF signal from the feed line distribution point to the first antenna element comprises enabling an RF switch coupled to the circuit board at a multiple of half a wavelength of the RF signal from the feed line distribution point.

16. The method of claim 15, wherein the RF switch comprises a PIN diode.

17. The method of claim 15, wherein the RF switch is coupled to the circuit board at an offset from the feed line dispense point that is a multiple of a half wavelength of the RF signal, the offset based on a stray capacitance of at least one of the feed line dispense point and the RF switch.

18. The method of claim 15, wherein coupling the RF signal to the first antenna element and the second antenna element comprises energizing a first feed line of the circuit board and a second feed line of the circuit board, the second feed line comprising a multiple of half a wavelength compared to the first feed line.

19. The method of claim 15, wherein coupling the RF signal to the first antenna element and the second antenna element comprises routing the RF signal to the first antenna element and the second antenna element such that the first antenna element is co-phased with the second antenna element.

20. The method of claim 15, wherein the first periphery and the second periphery are on opposite edges of the circuit board.

21. The method of claim 15, wherein the first antenna element comprises a modified dipole.

22. The method of claim 21, wherein the first antenna element further comprises a reflector.

23. A peripheral antenna system comprising:

a communication circuit located in an interior region of a circuit board, the communication circuit configured to generate an RF signal to a feeder distribution point of the circuit board;

a first means for radiating the RF signal in a first directional radiation pattern, the first means formed within a first periphery of the circuit board;

a second means for radiating the RF signal in a second directional radiation pattern offset from the first directional radiation pattern, the second means formed at a second periphery of the circuit board; and

means for coupling the feeder distribution point to the first means for radiating the RF signal and the second means for radiating the RF signal, wherein the first means and the second means collectively produce omnidirectional and horizontally polarized radiation coverage in the plane of the circuit board when the first means and the second means are coupled to the feeder distribution point,

wherein the means for coupling further comprises means for selectively coupling the feeder distribution point to the first means and the second means, and the means for selectively coupling comprises a first RF switch located at a multiple of half a wavelength from the feeder distribution point, the first RF switch configured to selectively couple the feeder distribution point to the first means.

24. A peripheral antenna system according to claim 23, wherein the first means for radiating the RF signal comprises means for converging the first directional radiation pattern.

25. A circuit board, comprising:

a feeder distribution point configured to distribute RF signals generated by communication circuitry located in an interior region of the circuit board;

a first antenna element located proximate a first periphery of the circuit board, the first antenna element configured to generate a first directional radiation pattern when coupled to the RF signal;

a second antenna element located proximate a second periphery of the circuit board, the second antenna element configured to produce a second directional radiation pattern offset from the first directional radiation pattern when coupled to the RF signal, wherein the first antenna element and the second antenna element collectively produce omnidirectional and horizontally polarized radiation coverage in the plane of the circuit board when coupled to the RF signal; and

a switching network adapted to receive a first RF switch and a second RF switch, the switching network configured to couple the feed line distribution point to the first antenna element when the first RF switch is enabled and to couple the feed line distribution point to the second antenna element when the second RF switch is enabled;

wherein the switching network is configured with a first RF switch at a multiple of half a wavelength of the RF signal from the feeder distribution point.

26. The circuit board of claim 25, wherein the first antenna element comprises a modified dipole.

27. The circuit board of claim 26, wherein the first antenna element further comprises a reflector configured to focus the radiation pattern of the first antenna element.

28. The circuit board of claim 26, wherein the first antenna element further comprises a reflector configured to broaden the frequency response of the first antenna element.

29. The circuit board of claim 25, wherein the first antenna element comprises a first dipole component formed on a surface of the circuit board, a second dipole component formed on an opposite surface of the circuit board, the second dipole component coupled to an internal ground layer of the circuit board.