Reducing stray capacitance in antenna element switching

• US 20070247255A1
• Filed: 04/30/2007
• Published: 10/25/2007
• Est. Priority Date: 08/18/2004
• Status: Active Grant

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: Ruckus Wireless, Inc. (CommScope Holding Company, Inc.)
• Inventors: Shtrom, Victor
• Granted Patent: US 7,696,946 B2
• Time in Patent Office: Days
• US Class Current: 333/17.300
• CPC Class Codes: H01P 1/15 by semiconductor devices
• CPC Class Codes: H03H 7/383 comprising distributed impedance elements together with lumped impedance elements

Abstract

An antenna array may include an antenna element configured to receive an RF signal. A PIN diode may selectively couple the antenna element to an RF source. Biasing the PIN diode may cancel the received RF signal at a stub coupled to the diode thereby reducing stray capacitance of the PIN diode. A method for switching antenna elements is also disclosed. A PIN diode coupled to an antenna element is biased thereby reflecting the received RF signal out-of-phase within a stub such that the signal is cancelling and stray capacitance of the PIN diode is reduced.

Claims

1. An antenna array comprising:

an antenna element configured to receive an RF signal; and

a PIN diode coupled to the antenna element, wherein biasing the PIN diode influences the received RF signal.

2. The antenna array of claim 1, wherein the PIN diode is forward biased and the received RF signal is cancelled at a stub coupled to the PIN diode.

3. The antenna array of claim 2, wherein the RF signal is cancelled by reflecting the RF signal out-of-phase within the stub.

4. The antenna array of claim 3, wherein the cancellation of the RF signal reduces stray capacitance of the PIN diode.

5. The antenna array of claim 2 further comprising an inductor coupled to the stub, wherein the inductor draws the RF signal to the stub via the forward biased PIN diode.

6. The antenna array of claim 1, wherein the PIN diode is reverse biased and the received RF signal is allowed to propagate at the antenna element.

7. The antenna array of claim 2, wherein the stub is one-quarter of the wavelength of the RF signal in length.

8. The antenna array of claim 5, wherein the inductor is a chip inductor with a self-resonance at the frequency of the RF signal.

9. The antenna array of claim 1, wherein the antenna element is configured to be selectively coupled to an RF source by the PIN diode, the PIN diode being associated with the antenna element.

10. The antenna array of claim 9, wherein the antenna element is a part of a series of antenna elements that may each be selectively coupled to the RF source by a PIN diode associated with each of the series of antenna elements.

11. The antenna array of claim 10, wherein selectively coupling one or more antenna elements in the series of antenna elements to the RF source generates one or more directional radiation pattern substantially in the plane of the one or more antenna elements.

12. The antenna array of claim 11, wherein a combined radiation pattern resulting from the selective coupling of the one or more antenna elements in the series of antenna elements is substantially omnidirectional.

13. An antenna array, comprising:

an antenna element configured to receive an RF signal;

a PIN diode coupled to the antenna element, wherein forward biasing of the PIN diode cancels the received RF signal at a stub coupled to the PIN diode by reflecting the RF signal out-of-phase within the stub, the cancellation of the RF signal reducing stray capacitance of the PIN diode; and

a chip inductor coupled to the stub with a self-resonance at the frequency of the RF signal, the inductor configured to draw the RF signal to the stub via the forward biased PIN diode.

14. The antenna array of claim 13, wherein the antenna element is a part of a series of antenna elements that may be selectively coupled to an RF source by an associated PIN diode and selectively coupling one or more antenna elements in the series of antenna elements to the RF source generates one or more directional radiation patterns substantially in the plane of the one or more antenna elements.

15. The antenna array of claim 14, wherein a combined radiation pattern that results from the selective coupling of the one or more antenna elements in the series of antenna elements is substantially omnidirectional.

16. A method for reducing stray capacitance in antenna element switching, comprising:

receiving an RF signal within an antenna element; and

biasing a PIN diode coupled to the antenna element, wherein biasing the PIN diode influences the received RF signal.

17. The method of claim 16, wherein the PIN diode is forward biased and the received RF signal is cancelled at a stub coupled to the PIN diode by reflecting the RF signal out-of-phase within the stub.

18. The method of 17, wherein the cancellation of the RF signal reduces stray capacitance of the PIN diode.

19. The method of claim 18, wherein the antenna element is a part of a series of antenna elements that may be selectively coupled to an RF source by a PIN diode individually associated with each of the series of antenna elements.

20. The method of claim 19, further comprising:

selectively coupling one or more antenna elements in the series of antenna elements to the RF source; and

generating a directional radiation pattern substantially in the plane of the one or more antenna elements, wherein a combined radiation pattern resulting from the selective coupling of the one or more antenna elements in the series of antenna elements generates a substantially omnidirectional radiation pattern.