Claims
- 1. An antenna system for transmitting and receiving electromagnetic signals, the antenna system comprising:
- a plurality of radiators;
- a distribution network, coupled to each of the radiators, for communicating the electromagnetic signals from and to each of the radiators; and
- a feedback system coupled relative to the distribution network for generating a feedback signal to at least one of the radiators, the feedback system including at least one feedback element disposed offset relative to a pair of radiators within the plurality of radiators for generating the feedback signal in response to receiving the electromagnetic signals transmitted by said pair of radiators, the feedback signal operative to cancel a leakage signal present at the distribution network and thereby increase the port to port isolation of the antenna system.
- 2. The antenna system recited in claim 1 further comprising a radome coupled relative to the distribution network for protecting the radiators and the distribution network from exposure to the operating environment of the antenna system, wherein the feedback element is coupled to the radome for generating the feedback signal in response to receiving the electromagnetic signals transmitted by the radiators.
- 3. The antenna system recited in claim 2, wherein each feedback element is connected to an interior surface of the radome and positioned proximate to at least one of the radiators.
- 4. The antenna system recited in claim 2, wherein the feedback element comprises an electrically conductive material having a length sufficient for resonating at a frequency of the transmitted electromagnetic signals.
- 5. The antenna system recited in claim 4, wherein the feedback element is sized having a width equal to a maximum of 1/8 wavelengths.
- 6. The antenna system recited in claim 2, wherein the feedback element comprises an electrically conductive material sized sufficiently for resonating at a frequency of the transmitted electromagnetic signals.
- 7. The antenna system recited in 6, wherein the feedback element is in the form of a circular patch.
- 8. The antenna system recited in claim 1, wherein the feedback element is in the form of a conductive strip having a length of 1/2 wavelength.
- 9. The antenna system recited in claim 1, wherein the feedback element is in the form of a conductive strip positioned on a nonconductive material, the conductive strip thereby being electrically isolated from the distribution network.
- 10. The antenna system recited in claim 1, wherein the feedback element is capacitively coupled to at least one of the radiators, for generating the feedback signal in response to receiving the electromagnetic signals transmitted by the radiators.
- 11. The antenna system recited in claim 10, wherein the feedback element comprises an electrically conductive material having a length sufficient for resonating at the frequency of the transmitted electromagnetic signals.
- 12. The antenna system recited in claim 11, wherein the feedback element has a length of 1/8 wavelength.
- 13. The antenna system recited in claim 11, wherein the feedback element has a length of 3/10 wavelength.
- 14. The antenna system recited in claim 10, wherein the feedback element is capacitively coupled to each radiator at a position on the radiator where the voltage of the transmitted electromagnetic signals is at a maximum level, thereby promoting maximum electrical coupling of the transmitted electromagnetic signals to the feedback element.
- 15. The antenna system recited in claim 1, wherein the feedback system comprises at least one feedback element configured so to produce a rotational characteristic within the feedback signal.
- 16. An antenna system for transmitting and receiving electromagnetic signals, the antenna system comprising:
- a plurality of radiators;
- a distribution network, coupled to each of the radiators, for communicating the electromagnetic signals from and to each of the radiators; and
- a feedback system coupled relative to the distribution network for generating a feedback signal to at least one of the radiators, the feedback signal operative to cancel a leakage signal present at the distribution network and thereby increase the port to port isolation of the antenna system, said feedback system comprises at least one feedback post, coupled to the distribution network and positioned proximate to at least one of the radiators, for generating the feedback signal in response to receiving the electromagnetic signals transmitted by the radiators.
- 17. The antenna system recited in claim 16, wherein each feedback post is positioned between the radiators and comprises electrically conductive material having a length sufficient for resonating at the frequency of the transmitted electromagnetic signals.
- 18. An antenna system for transmitting and receiving electromagnetic signals, the antenna system comprising:
- a plurality of radiators;
- a distribution network, coupled to each of the radiators, for communicating the electromagnetic signals from and to each of the radiators; and
- a feedback system coupled relative to the distribution network for generating a feedback signal to at least one of the radiators, the feedback signal operative to cancel a leakage signal present at the distribution network and thereby increase the port to port isolation of the antenna system, the feedback system comprises at least one feedback wire, coupled relative to the distribution network and positioned so to electrically cooperate with at least one of the radiators, for generating the feedback signal in response to receiving the electromagnetic signals transmitted by the radiators.
- 19. The antenna system recited in claim 18, wherein the feedback wire and the distribution network are separated by a nonconductive material thereby positioning the feedback wire above a surface of the distribution network.
- 20. The antenna system recited in claim 19, wherein the feedback wire comprises a loop sized to promote resonance at the frequency of the transmitted electromagnetic signals.
- 21. An antenna system for transmitting and receiving electromagnetic signals, the antenna system comprising:
- a plurality of radiators;
- a distribution network, coupled to each of the radiators, for communicating the electromagnetic signals from and to each of the radiators;
- a feedback system coupled relative to the distribution network for generating a feedback signal to at least one of the radiators, the feedback signal operative to cancel a leakage signal present at the distribution network and thereby increase the port to port isolation of the antenna system; and
- a radome coupled relative to the distribution network, and wherein the feedback system comprises a plurality of feedback elements coupled to the radome and configured such that the distances between each of the plurality of feedback elements is uneven.
- 22. An antenna system for transmitting and receiving electromagnetic signals, the antenna system comprising:
- a plurality of radiators;
- a distribution network, coupled to each of the radiators, for communicating the electromagnetic signals from and to each of the radiators;
- a feedback system coupled relative to the distribution network for generating a feedback signal to at least one of the radiators, the feedback signal operative to cancel a leakage signal present at the distribution network and thereby increase the port to port isolation of the antenna system; and
- a radome coupled relative to the distribution network and wherein the feedback system comprises a plurality of feedback elements coupled to the radome and configured in a nonsymmetrical pattern with respect to the plurality of radiators.
- 23. A method for adjusting a port to port isolation characteristic of an antenna system, comprising the steps of:
- (a) performing baseline measurements on the antenna system to generate an initial set of selected performance parameters for the antenna system;
- (b) presenting a feedback signal having an amplitude characteristic and a phase characteristic to the antenna system, the feedback signal operative to cancel at least a portion of a leakage signal at an output port of the antenna system;
- (c) monitoring the port to port isolation characteristic of the antenna system while presenting the feedback signal to the antenna system; and
- (d) adjusting the feedback signal by varying at least one of the amplitude characteristic and the phase characteristic of the feedback signal until the port to port isolation characteristic is set to a desired isolation level.
- 24. The method recited in claim 23 further comprising the steps of:
- (e) responsive to adjusting the feedback signal, performing the baseline measurements on the antenna system to generate a second set of selected performance parameters for the antenna system; and
- (f) comparing the initial set of selected performance characteristics to the second set of selected performance characteristics to determine if the performance of the antenna system has been degraded by presenting the feedback signal to the antenna system.
- 25. The method recited in claim 24 further comprising the step of
- (g) repeating steps (b)-(f) until the desired isolation level is achieved without degrading the performance of the antenna system.
- 26. The method recited in claim 23, wherein the step of presenting the feedback signal to the antenna system comprises the step of:
- placing a feedback element proximate to one of a plurality of radiators for the antenna system so that the feedback element can respond to the radiator transmitting an electromagnetic signal by generating the feedback signal.
- 27. The method recited in claim 26, wherein the step of adjusting the feedback signal comprises adjusting the position of the feedback element relative to the radiator to support electrical coupling of the feedback signal between the feedback element and the radiator.
- 28. The method recited in claim 23, wherein the step of presenting the feedback signal to the antenna system comprises the steps of:
- placing a feedback element on a section of a radome for the antenna system; and
- placing the radome section proximate to one of a plurality of radiators of the antenna system so that the feedback element can respond to the radiator transmitting an electromagnetic signal by generating the feedback signal.
- 29. The method recited in claim 28, wherein the step of adjusting the feedback signal comprises:
- (i) adjusting the position of the radome section relative to the particular radiator to support generation of the feedback signal by the feedback element and reception of the feedback signal by the radiator;
- (ii) placing another one of the radome section proximate to another one of the radiators if the desired isolation level is not achieved for the antenna system; and
- (iii) adjusting the position of the other radome section until the desired isolation level is achieved by placement of the combination of the radome section and the other radome section proximate to the radiators of the antenna system.
- 30. The method recited in claim 29 further comprising the step of repeating steps (ii) and (iii) until the desired isolation level is achieved by placement of the combination of the radome section and the other radome section proximate to the radiators of the antenna system.
- 31. The method recited in claim 23, wherein the antenna system comprises a plurality of radiators extending adjacent to a ground plane, and the step of presenting the feedback signal to the antenna system comprises placing a conductive post proximate to one of the radiators and electrically isolated from the ground plane, the conductive post operative to resonate in response to an electromagnetic signal transmitted by one of the radiators and to generate the feedback signal for communication to the radiator.
- 32. The method recited in claim 23, wherein the antenna system comprises a plurality of radiators extending adjacent to a ground plane, and the step of presenting the feedback signal to the antenna system comprises placing a conductive loop proximate to one of the radiators and electrically isolated from the ground plane, the conductive loop operative to resonate in response to an electromagnetic signal transmitted by one of the radiators and to generate the feedback signal for communication to the radiator.
- 33. The method recited in claim 23, wherein the antenna system comprises a plurality of radiators extending adjacent to a ground plane, and the step of presenting the feedback signal to the antenna system comprises placing a conductive strip positioned on a nonconductive material proximate to at least one radiator, the conductive strip thereby being electrically isolated from the ground plane structure.
- 34. The method recited in claim 23, wherein the antenna system comprises a plurality of radiators, and the step of presenting the feedback signal to the antenna system comprises capacitively coupling a conductive strip to one of the radiators, the conductive strip operative to resonate in response to an electromagnetic signal transmitted by one of the radiators and to generate the feedback signal for communication to the radiator.
- 35. An antenna system for transmitting and receiving electromagnetic signals, the antenna system comprising:
- a plurality of crossed-dipole radiators, each crossed-dipole including a first pair of arms and a second pair of arms;
- a distribution network, coupled to each of the radiators, for communicating the electromagnetic signals from and to each of the radiators; and
- a feedback system coupled relative to the distribution network for generating a feedback signal to at least one of the radiators, the feedback system including at least one feed back element disposed between a first pair of arms and a second pair of arms of a respective crossed-dipole for generating the feedback signal in response to receiving the electromagnetic signals transmitted by the pairs of arms of the crossed-dipole radiator, the feedback signal operative to cancel a leakage signal present at the distribution network and thereby increase the port to port isolation of the antenna system.
RELATED APPLICATIONS
This application is related to U.S. patent application Ser. No. 08/572,529, filed Dec. 14, 1995 and U.S. patent application Ser. No. 08/733,399, filed Oct. 18, 1996.
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EPX |
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