Base station antenna system employing circular polarization and angular notch filtering

• US 7,593,753 B1
• Filed: 07/19/2005
• Issued: 09/22/2009
• Est. Priority Date: 07/19/2005
• Status: Expired due to Fees

• Current Assignee: Sprint Communications Company LP (Deutsche Telekom AG)
• Original Assignee: Sprint Communications Company LP (Deutsche Telekom AG)
• Inventors: Rausch, Walter F.
• Primary Examiner(s): Nguyen; Duc
• Assistant Examiner(s): Rego; Dominic E
• Application Number:
  US11/184,700
• Time in Patent Office: 1,526 Days
• Field of Search: 455/13.3, 455/19, 455/25, 455/63.4, 455/82, 455/83, 455/562.1, 455/575.5, 455/575.7, 455/561, 342/359, 342/361, 342/363, 342/365, 343/276.1, 343/751, 343/754, 343/756, 343/778, 343/824
• US Class Current: 455/562.1
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

An antenna system for transferring wireless communication signals between a wireless communication device and a base station is provided. The system includes a first linear polarization antenna associated with a first signal, and a second linear polarization antenna associated with a second signal and oriented perpendicularly to the first antenna. The first and second antennas are coupled to a phase shifter through first and second signal attenuators configured to selectively attenuate the first and second signals, respectively. The phase shifter is also coupled with the base station, and is configured to delay the phase of the first signal by ninety degrees. In addition, an attenuator controller coupled with the first and second attenuators is configured to control when the first and second signal attenuators attenuate the first and second signals.

Claims

1. An antenna system for transferring wireless communication signals between a wireless communication device and a base station, the antenna system comprising:

a first linear polarization antenna;

a second linear polarization antenna oriented perpendicularly to the first linear polarization antenna;

a first signal attenuator coupled with the first linear polarization antenna, the first signal attenuator configured to selectively attenuate a first signal associated with the first linear polarization antenna;

a second signal attenuator coupled with the second linear polarization antenna, the second signal attenuator configured to selectively attenuate a second signal associated with the second linear polarization antenna;

a phase shifter coupled with the first and second signal attenuators and the base station, wherein the phase shifter is configured to induce a 90-degree phase delay in the first signal to generate circular polarization for the antenna system, wherein the phase shifter exhibits a characteristic impedance of 50 ohms;

an attenuator controller coupled with the first and second signal attenuators, the attenuator controller configured to control when the first and second signal attenuators attenuate the first signal and the second signal to form a notch in the circular polarization at a range of polarization angles;

a first cable coupling the phase shifter with the first signal attenuator, the first cable exhibiting a characteristic impedance of 50 ohms, the first cable comprising a length;

a second cable coupling the phase shifter with the second signal attenuator, the second cable exhibiting a characteristic impedance of 50 ohms, the second cable comprising a length substantially equal to the length of the first cable; and

a third cable coupling the phase shifter with the base station, the third cable exhibiting a characteristic impedance of 50 ohms.

2. The antenna system of claim 1, wherein the first linear polarization antenna and the second linear polarization antenna each exhibit a characteristic impedance of 50 ohms.

3. The antenna system of claim 1, wherein the first signal attenuator and the second signal attenuator each exhibit a characteristic impedance of 50 ohms.

4. The antenna system of claim 1, wherein the first signal attenuator and the second signal attenuator each comprise an electronic switch configured to selectively eliminate the first and second signals.

5. The antenna system of claim 1, wherein the first signal attenuator and the second signal attenuator each comprise an electronic circuit configured to reduce the power of the first and second signals.

6. The antenna system of claim 1, the phase shifter comprising an electronic circuit.

7. The antenna system of claim 1, the attenuator controller comprising an electronic circuit synchronized with the first signal and the second signal, the attenuator controller configured to selectively activate the first and second signal attenuators during periods of time associated with interference from other electromagnetic sources.

8. The antenna system of claim 7, the attenuator controller further comprising a processor configured to execute instructions for determining the periods of time associated with the interference from the other electromagnetic sources.

9. The antenna system of claim 8, the periods of time being determined from previously detected interference, and signal polarization associated therewith.

10. The antenna system of claim 8, the periods of time being determined from previously dropped calls, and signal polarization associated therewith.

11. The antenna system of claim 1, wherein the first signal and the second signal are linearly-polarized transmission signals combined to produce a clockwise circularly-polarized transmission signal to the wireless communication device.

12. The antenna system of claim 1, wherein the first signal and the second signal are linearly-polarized transmission signals combined to produce a counter-clockwise circularly-polarized transmission signal to the wireless communication device.

13. The antenna system of claim 1, wherein the first signal and the second signal are linearly-polarized signals received by the first linear polarization antenna and the second linear polarization antenna from the wireless communication device.

14. An antenna system for transferring wireless communication signals between a wireless communication device and a base station, the antenna system comprising:

a first linear polarization antenna;

a second linear polarization antenna oriented perpendicularly to the first linear polarization antenna;

a first signal attenuator coupled with the first linear polarization antenna, the first signal attenuator configured to selectively attenuate a first signal associated with the first linear polarization antenna;

a second signal attenuator coupled with the second linear polarization antenna, the second signal attenuator configured to selectively attenuate a second signal associated with the second linear polarization antenna;

a phase shifter coupled with the first and second signal attenuators and the base station, wherein the phase shifter is configured to induce a 90-degree phase delay in the first signal to generate circular polarization for the antenna system, and wherein the phase shifter comprises a phase harness;

an attenuator controller coupled with the first and second signal attenuators, the attenuator controller configured to control when the first and second signal attenuators attenuate the first signal and the second signal to form a notch in the circular polarization at a range of polarization angles;

wherein the phase harness comprises;

a T-connector;

a first cable coupling the T-connector with the first signal attenuator, the first cable comprising a length of an integral multiple of an electrical wavelength of the first signal and the second signal, plus one-quarter of the electrical wavelength of the first signal and the second signal; and

a second cable coupling the T-connector with the second signal attenuator, the second cable comprising a length of the integral multiple of the electrical wavelength of the first signal and the second signal; and

wherein the antenna system further comprises a third cable coupling the T-connector with the base station.

15. The antenna system of claim 14, wherein each of the first cable and the second cable comprise coaxial cable exhibiting a characteristic impedance of 100 ohms, and wherein the third cable comprises coaxial cable exhibiting a characteristic impedance of 50 ohms.

16. The antenna system of claim 14, the attenuator controller comprising an electronic circuit synchronized with the first signal and the second signal, the attenuator controller configured to selectively activate the first and second signal attenuators during periods of time associated with interference from other electromagnetic sources.

17. The antenna system of claim 16, the attenuator controller further comprising a processor configured to execute instructions for determining the periods of time associated with the interference from the other electromagnetic sources.

18. A base station comprising an antenna system for transferring wireless communication signals between a wireless communication device and the base station, the antenna system comprising:

a first linear polarization antenna;

a second linear polarization antenna oriented perpendicularly to the first linear polarization antenna;

a first signal attenuator coupled with the first linear polarization antenna, the first signal attenuator configured to selectively attenuate a first signal associated with the first linear polarization antenna;

a second signal attenuator coupled with the second linear polarization antenna, the second signal attenuator configured to selectively attenuate a second signal associated with the second linear polarization antenna;

a phase shifter coupled with the first and second signal attenuators and the base station, wherein the phase shifter is configured to induce a 90-degree phase delay in the first signal; and

an attenuator controller coupled with the first and second signal attenuators, the attenuator controller configured to control when the first and second signal attenuators attenuate the first signal and the second signal;

wherein the attenuator controller comprises an electronic circuit synchronized with the first signal and the second signal, and wherein the attenuator controller is configured to selectively activate the first and second signal attenuators during periods of time associated with interference from other electromagnetic sources.

19. A wireless communication network comprising the base station of claim 18.

20. The wireless communication network of claim 19, wherein the base station is a base transceiver station for broadband wireless communication.