Fractal antenna system and method for improved wireless telecommunications

• US 7,088,965 B1
• Filed: 01/08/2002
• Issued: 08/08/2006
• Est. Priority Date: 01/08/2002
• Status: Expired due to Term

• Current Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Ngan, John Cheong-Wai
• Primary Examiner(s): Beamer, Temica
• Application Number:
  US10/041,326
• Time in Patent Office: 1,673 Days
• Field of Search: 455/562.1, 455/500, 455/501, 455/504, 455/63.1, 455/63.4, 455/65, 455/67.11, 455/67.13, 455/84, 455/101, 455/114.2, 455/115.1, 455/115.3, 455/132, 455/133, 455/134, 455/135, 455/137, 455/226.1, 455/226.2, 455/226.3
• US Class Current: 455/114.2
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 15/0093 having a fractal shape
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H01Q 9/40 Element having extended radiating surface
• CPC Class Codes: H04B 7/0871 using different reception schemes, at least one of them being a diversity reception scheme

Abstract

A method and system having one or more fractal antennas for communicating signals. The fractal antennas are coupled to a diversity receive circuit for receiving the signals. The diversity receive circuit provides an output signal based on a combination of the receive signals. The fractal antennas and the diversity receive circuit can help compensate for, or reduce the effects of fading. Additionally, a transmitter provides a transmit signal. One of the fractal antennas may both transmit and receive signals. Alternatively, a transmit antenna, separate from the receive antennas, may transmit the transmit signals. The fractal antennas may also be fractal arrays for providing additional resistance to fading.

Claims

1. A device comprising:

a first fractal antenna for receiving a first set of signals;

a second fractal antenna for receiving a second set of signals; and

a diversity receive circuit coupled to the first fractal antenna for receiving the first set of signals and to the second fractal antenna for receiving the second set of signals, wherein the diversity receive circuit includes a combiner for providing a combiner output signal based on a combination of the first set of signals and the second set of signals, wherein the combiner output signal is stronger than the first set of signals and is stronger than the second set of signals; and

wherein the first and second fractal antennas are spaced from each other in an optimized manner so as to reduce the likelihood that both antennas are in an interference null zone for signal radiation of an expected wavelength.

2. The device of claim 1, further comprising a transmitter coupled to a third fractal antenna to transmit a third set of signals.

3. The device of claim 1, further comprising a transmitter coupled to the first fractal antenna to transmit a third set of signals on the first fractal antenna.

4. The device of claim 1, wherein the device is a wireless mobile station.

5. The device of claim 1, wherein the device is a base station.

6. The device of claim 1, wherein the first and second fractal antenna are physically separated by approximately an integral number of fractions of a wavelength.

7. The device of claim 1, wherein the diversity receive circuit provides the output signal for the compensation of fading and wherein said fading is caused by an event selected from the group consisting of multipath interference, signal obstruction, terrain absorption, diffraction, and refraction.

8. A device comprising:

a first fractal antenna for receiving a first set of signals;

a second fractal antenna for receiving a second set of signals;

a transmitter for generating a third set of signals;

a bi-directional coupler connected to the first fractal antenna and to the transmitter, wherein the bi-directional coupler receives the first set of signals from the first fractal antenna and transmits the third set of signals from the transmitter to the first fractal antenna;

a combiner connected to the second fractal antenna and to the bi-directional coupler for producing a combiner output signal based on a combination of the first set of signals from the bi-directional coupler and the second set of signals from the second fractal antenna, wherein the combiner output signal is stronger than the first set of signals from the bidirectional coupler and is stronger than the second set of signals from the second fractal antenna;

a receive circuit coupled to the combiner for receiving the combiner output signal; and

wherein the first and second fractal antennas are spaced from each other in an optimized manner so as to reduce the likelihood that both antennas are in an interference null zone for signal radiation of an expected wavelength.

9. The device of claim 8, where the combiner is a max-ratio combiner.

10. The device of claim 8, where the bi-directional coupler is a duplexer comprising:

a receive band-pass filter coupling the first set of signals from the first fractal antenna to the combiner; and

a transmit band-pass filter coupling the third set of signals from the transmitter to the first fractal antenna.

11. The device of claim 8, where the bi-directional coupler comprises a circulator.

12. The device of claim 8, where the bi-directional coupler comprises a switch connected to the first fractal antenna, to the combiner, and to the transmitter, wherein:

the transmitter is coupled to the first fractal antenna to transmit the third set of signals when the transmitter is in a transmit mode,

the first fractal antenna is coupled to the combiner for receiving the first set of signals when the receive circuit is in a receive mode.

13. The device of claim 8, wherein the device is a mobile station.

14. The device of claim 8, wherein the device is a base station.

15. The device of claim 8, wherein the first and second fractal antenna are physically separated by an integral number of fractions of a signal wavelength.

16. A device comprising:

a first fractal antenna for receiving a first set of signals;

a second fractal antenna for receiving a second set of signals;

a diversity receiver circuit coupled to the first fractal antenna to receive the first set of signals and to the second fractal antenna to receive the second set of signals, wherein the diversity receiver circuit includes a combiner for providing an output signal based on a combination of the first set of signals and the second set of signals, wherein the combiner output signal is stronger than the first set of signals and is stronger than the second set of signals;

a down-converter coupled to the diversity receiver circuit for converting the combiner output signal into a base band receive signal;

an up-converter for converting a base band transmit signal to a third set of signals; and

a transmitter coupled to the up-converter, wherein the transmitter is coupled to the first fractal antenna for transmitting the third set of signals on the first fractal antenna; and

wherein the first and second fractal antennas are spaced from each other in an optimized manner so as to reduce the likelihood that both antennas are in an interference null zone for signal radiation of an expected wavelength.

17. The device of claim 16, further comprising a processor coupled to the up-converter and to the down-converter for processing the base band receive signal and the base band transmit signal.

18. The device of claim 17, further comprising:

a microphone coupled to the processor for converting voice signals into the base band transmit signal; and

a speaker coupled to the processor for converting the base band receive signal to an audio signal.

19. A device comprising:

a fractal array for receiving a set of RF receive signals and for transmitting a set of RF transmit signals;

a bi-directional coupler connected to the fractal array for receiving the set of RF receive signals and for transmitting the set of RF transmit signals;

a receiver coupled to the bidirectional coupler for receiving the set of RF receive signals, wherein the receiver includes a combiner for providing a combiner output signal based on a combination of RF receive signals within the set of RF receive signals, wherein the combiner output signal is stronger than each of the RF receive signals in the set of RF receive signals;

a transmitter coupled to the bi-directional coupler for transmitting the set of RF transmit signals; and

wherein the fractal array comprises first and second fractal antennas are spaced from each other in an optimized manner so as to reduce the likelihood that both antennas are in an interference null zone for signal radiation of an expected wavelength.

20. A method for receiving a radio frequency signal method comprising:

using a first fractal antenna to receive a first signal;

using a second fractal antenna to receive a second signal; and

using a combiner to produce a combiner output signal that is stronger than the first signal and is stronger than the second signal; and

wherein the first and second fractal antennas are spaced from each other in an optimized manner so as to reduce the likelihood that both antennas are in an interference null zone for signal radiation of an expected wavelength.

21. The method of claim 20 further comprising transmitting a third signal.

22. The method of claim 21, wherein the first fractal antenna receives the first signal and transmits the third signal.

23. The method of claim 21, wherein a third fractal antenna transmits the third signal.