Circuit board having a peripheral antenna apparatus with selectable antenna elements and selectable phase shifting
View Patent ↗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 and selectable phase shifting. 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, and includes a selectable phase shifter to allow the phase of the antenna elements to be shifted by 180 degrees. The phase shifter includes a first RF switch and two ¼-wavelength delay lines of PCB traces or delay elements and a second RF switch. The phase shifter selectively provides a straight-through path, a 180 degree phase shift, a high impedance state, or a notch filter.
1. A system for selective phase shifting, comprising:
an input port configured to receive an RF signal;
a straight-through path coupled to the input port and including a first RF switch;
a long path of predetermined length coupled to the input port and including a second RF switch coupled to a ground, the long path comprising a first delay path and a second delay path;
a delay element coupled to the first and second delay paths in series with the second RF switch;
the first delay path comprising a first trace line of ¼-wavelength of the RF signal less a phase delay of the delay element;
the second delay path comprising a second trace line of ¼-wavelength of the RF signal less a phase delay of the delay element;
the first delay path and the second delay path selectively coupled to ground by application of a forward bias to the second RF switch; and
an output port coupled to the straight-through path and the long path.
2. The system of claim 1 wherein the predetermined length comprises a 180 degree phase delay between the input port and the output port.
3. The system of claim 1 wherein the predetermined length comprises a multiple of 90 degree phase shift between the input port and the output port.
4. The system of claim 1 wherein the straight-through path is configured to selectively transmit the RF signal from the input port to the output port by application of a forward bias to the first RF switch.
5. The system of claim 1 wherein the long path is configured to selectively present a high impedance to both the input port and the output port by application of a forward bias to the second RF switch.
6. The system of claim 1 wherein the long path is configured to selectively receive the RF signal from the input port, apply a multiple of 90 degree phase shift to the RF signal, and transmit the phase shifted RF signal to the output port by application of an appropriate bias to the second RF switch.
7. The system of claim 1 wherein the long path is configured to selectively receive the RF signal from the input port, apply a 180 degree phase shift to the RF signal, and transmit the phase shifted RF signal to the output port by application of a zero or reverse bias to the second RF switch.
8. The system of claim 1 wherein the long path is divided in half by the second RF switch.
9. The system of claim 1 wherein the first RF switch and the second RF switch comprise PIN diodes.
10. A system for selective phase shifting, comprising:
an input port configured to receive an RF signal;
a straight-through path coupled to the input port and including a first RF switch;
a long path of predetermined length coupled to the input port and including a second RF switch coupled to a ground, the long path comprising a first half path and a second half path,
the first half path including a first delay element and a first trace line of ¼-wavelength of the RF signal less a phase delay of the first delay element,
the second half path including a second delay element and a second trace line of ¼-wavelength of the RF signal less a phase delay of the second delay element,
the first half path and the second half path selectively coupled to ground by application of a zero or reverse bias to the second RF switch for a phase delay of ½-wavelength of the RF signal; and
an output port coupled to the straight-through path and the long path.
11. The system of claim 10 wherein the long path is configured to selectively present a high impedance to the input port and the output port by application of a forward bias to the second RF switch.
12. The system of claim 10 wherein the long path is configured to selectively receive the RF signal from the input port, apply a multiple of 90 degree phase shift to the RF signal, and transmit the phase shifted RF signal to the output port by application of an appropriate bias to the second RF switch.
13. The system of claim 10 wherein the first RF switch and the second RF switch comprise PIN diodes.
14. The system of claim 10 wherein the predetermined length comprises a multiple of 90 degree phase shift between the input port and the output port.
15. The system of claim 10 wherein the straight-through path is configured to selectively transmit the RF signal from the input port to the output port by application of a forward bias to the first RF switch.
16. A method for phase shifting an RF signal, comprising:
receiving an RF signal at an input port;
disabling a straight-through path coupled to the input port by applying a zero or reverse bias to a first RF switch included in the straight-through path;
phase shifting the RF signal by enabling a long path of a predetermined length coupled to the input port by applying a zero or reverse bias to a second RF switch included in the long path, the predetermined length of the long path being a multiple of one half of a wavelength of the RF signal, the second RF switch coupled to a ground; and
transmitting the phase shifted RF signal to an output port coupled to the straight-through path and the long path.
17. The method of claim 16 wherein the long path is divided in half by the second RF switch.
18. A method for phase shifting an RF signal, comprising:
receiving an RF signal at an input port;
disabling a straight-through path coupled to the input port by applying a zero or reverse bias to a first RF switch included in the straight-through path;
phase shifting the RF signal by enabling a long path of a predetermined length coupled to the input port by applying a zero or reverse bias to a second RF switch included in the long path, the long path including a delay element, the second RF switch coupled to a ground; and
transmitting the phase shifted RF signal to an output port coupled to the straight-through path and the long path.
19. The method of claim 18 wherein the long path is of length equal to one half of a wavelength of the RF signal minus the phase delay presented by the delay element.
20. The method of claim 18 wherein the long path is of length equal to a multiple of one half of a wavelength of the RF signal minus the phase delay presented by the delay element.
21. The method of claim 18 wherein the predetermined length of the long path is one half of a wavelength of the RF signal.
22. The method of claim 18 wherein the long path is divided in half by the second RF switch.
23. An antenna apparatus having selectable antenna elements and selectable phase shifting, comprising:
communication circuitry located in a first area of a circuit board, the communication circuitry configured to generate an RF signal into an antenna feed port of the circuit board;
a first antenna element located near a first periphery of the circuit board, the first antenna element configured to produce a first directional radiation pattern when coupled to the antenna feed port; and
a phase shifter, the phase shifter including a straight-through path configured to selectively couple the antenna feed port to the first antenna element with a first PIN diode, the phase shifter further including a long path of predetermined length configured to selectively couple the antenna feed port to the first antenna element with a second PIN diode coupled to a ground, the phase shifter configured to selectively provide a zero degree phase shift, a 180 degree phase shift, and a multiple of 180 degree phase shift between the antenna feed port and the first antenna element.
24. The antenna apparatus of claim 23 , wherein the phase shifter is configured to selectively isolate the antenna feed port from the first antenna element.
25. The antenna apparatus of claim 23 , wherein the phase shifter is configured to selectively provide a zero degree phase shift between the antenna feed port and the first antenna element.
26. The antenna apparatus of claim 23 , wherein the phase shifter is configured to selectively provide a 180 degree phase shift between the antenna feed port and the first antenna element.
27. A system for selective phase shifting, comprising:
an input port configured to receive an RF signal;
a straight-through path coupled to the input port and including a first RF switch;
a long path of predetermined length coupled to the input port and including a second RF switch coupled to a ground, the long path comprising a first half path and a second half path,
the first half path including a first delay element and a first trace line of a multiple of ¼-wavelength of the RF signal less a phase delay of the first delay element,
the second half path including a second delay element and a second trace line of a multiple of ¼-wavelength of the RF signal less a phase delay of the second delay element,
the first half path and the second half path with a zero or reverse bias for the second RF switch results in a multiple of phase delay of ½-wavelength of the RF signal; and
an output port coupled to the straight-through path and the long path.
28. The system of claim 27 wherein the first RF switch and the second RF switch comprise PIN diodes.
29. The system of claim 27 wherein the first half path and the second half path are selectively coupled to ground by the second RF switch.
30. The system of claim 27 wherein the predetermined length comprises a multiple of 90 degree phase shift between the input port and the output port.
31. The system of claim 27 wherein the straight-through path is configured to selectively transmit the RF signal from the input port to the output port by application of a forward bias to the first RF switch.
32. The system of claim 27 wherein the long path is configured to selectively present a high impedance to the input port and the output port by application of a forward bias to the second RF switch.
33. The system of claim 27 wherein the long path is configured to selectively receive the RF signal from the input port, apply a multiple of 90 degree phase shift to the RF signal, and transmit the phase shifted RF signal to the output port by application of an appropriate bias to the second RF switch.