A circuit board for wireless communications includes communication circuitry for modulating and/or demodulating a radio frequency (RF) signal and an antenna apparatus for transmitting and receiving the RF signal, the antenna apparatus having selectable antenna elements located near one or more peripheries of the circuit board. A first antenna element produces a first directional radiation pattern; a second antenna element produces a second directional radiation pattern offset from the first radiation pattern. The antenna elements may include one or more reflectors configured to provide gain and broaden the frequency response of the antenna element. A switching network couples one or more of the selectable elements to the communication circuitry and provides impedance matching regardless of which or how many of the antenna elements are selected. Selecting different combinations of antenna elements results in a configurable radiation pattern; alternatively, selecting several elements may result in an omnidirectional radiation pattern.
1. An antenna system, comprising:
communication circuitry located in an interior area of a circuit board, the communication circuitry generating an RF signal and providing the RF signal into a feed line distribution point of the circuit board;
a plurality of antenna elements arranged proximate edges of the circuit board to surround the communication circuitry, wherein a first antenna element and a second antenna element in the plurality of antenna elements are arranged to produce respective directional radiation patterns oriented in substantially the same direction when coupled to the communication circuitry; and
a switching network that selectively couples one or more of the plurality of antenna elements to the communication circuitry, the switching network arranged between the plurality of antenna elements and the feed line distribution point.
2. The antenna system of claim 1 , wherein the first and the second antenna elements have substantially identical physical dimensions.
3. The antenna system of claim 1 , wherein the first and the second antenna elements are arranged along an axis substantially parallel to an edge of the circuit board.
4. The antenna system of claim 1 , wherein the first and the second antenna elements are arranged along an axis substantially perpendicular to an edge of the circuit board.
5. The antenna system of claim 1 , wherein at least one antenna element in the plurality of antenna elements has physical dimensions different than that of another antenna element in the plurality of antenna elements.
6. The antenna system of claim 1 , wherein the switching network maintains a match at the feed line distribution point of at least 10 dB return loss of the RF signal when one or more antenna elements in the plurality of antenna elements are coupled to the feed line distribution point.
7. The antenna system of claim 1 , wherein the switching network includes RF switches that selectively couple and decouple corresponding antenna elements in the plurality of antenna elements to the feed line distribution point, the RF switches respectively located at about a multiple of one-half wavelength from the feed-line distribution point.
8. The antenna system of claim 7 , further comprising feed lines coupling the RF switches to the corresponding antenna elements.
9. The antenna system of claim 8 , wherein each of the feed lines have substantially equal electrical length.
10. The antenna system of claim 7 , wherein a first feed line of the feed lines has an electrical length different from that of a second feed line of the feed lines by a multiple of one-half wavelength of the RF signal.
11. The antenna system of claim 10 , wherein the electrical length of the first feed line is different from that of the second feed line by an odd multiple of one-half wavelength of the RF signal.
12. The antenna system of claim 1 , wherein the switching network selectively changes a frequency response of one or more of the plurality of antenna elements.
13. The antenna system of claim 1 , wherein a given antenna element in the plurality of antenna elements is formed on a single layer of the circuit board.
14. An antenna system, comprising:
communication circuitry located in an interior area of a circuit board, the communication circuitry generating an RF signal;
a plurality of antenna elements arranged proximate edges of the circuit board to surround the communication circuitry, wherein a first antenna element and a second antenna element in the plurality of antenna elements are arranged to produce respective directional radiation patterns oriented in substantially the same direction when coupled to the communication circuitry, and wherein a given antenna element in the plurality of antenna elements includes a first portion on a first layer of the circuit board and coupled to a feed line on the first layer, and includes a second portion on a second layer of the circuit board and coupled to the first layer by an array of metalized vias; and
a switching network that selectively couples one or more of the plurality of antenna elements to the communication circuitry.