Metamaterial reconfigurable antennas

Abstract

Leaky wave antennas that can be reconfigured in pattern and / or polarization by exploiting the characteristic of metamaterial structures loaded with variable capacitor and inductors employ a Composite Right Left Handed (CRLH) unit cell with two independent DC biases used to actively change the group delay of the transmission line and the polarization of the radiated field while preserving good impedance matching. Different degrees of pattern and polarization reconfigurability are achieved by cascading multiple of these unit cells along a straight line, a circular line or a zigzag line while preserving high gain for all the antenna configurations and good impedance matching.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims benefit of U.S. Provisional Application No. 61 / 286,786 filed Dec. 16, 2009.TECHNICAL FIELD[0002]The present invention relates generally to the field of reconfigurable antennas. Specifically, the present invention relates to antennas that can be reconfigured in pattern and / or polarization by using metamaterial structures loaded with variable capacitor and inductorsBACKGROUND OF THE INVENTION[0003]The changing behavior of the wireless channel causes fluctuations in the level of received signal power. In order to limit the effect of the varying wireless channel on system performance, a possible solution is to adopt reconfigurable antenna systems capable of adaptively tuning their radiation characteristics in response to the multivariate channel. Radiation pattern shape, polarization state and frequency of operation can be tuned to accommodate the operating requirements. Different solutions employing different techniqu...

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Benefits of technology

[0005]To address the above-mentioned needs in the art, the invention described herein uses leaky wave antennas (LWAs) built using metamaterial structures loaded with tunable capacitors and inductors and specific DC bias networks to control the values of capacitance and inductance across the antenna. Three different reconfigurable antenna designs built using a LWA metamaterial structure are described. These antennas exploit the characteristics of Composite Right Left Handed (CRLH) materials to achieve high pattern and polarization reconfigurability, with good impedance matching in a compact antenna design.

[0006]In particular, the invention includes metamaterial reconfigurable antennas that uses varactor diodes to change characteristics of unit cell structures such as group delay of transmission lines, polarization and impedance, by changing the values of variable capacitors and / or inductors in response to independent DC biases provided by independent DC bias circuits. As they operate on a traveling wave and not a resonating wave basis, these antennas may enable significant improvements in gain and reconfigurability. By controlling the varactor diodes independently, the group delay, polarization and impedance may be more widely varied than standard unit cell structures that only change the group delay.

Problems solved by technology

Using these techniques allows generating different polarizations and radiation patterns but, especially when the antenna has several different configurations, it generally causes some of the antenna configurations to suffer of low gain or impedance mismatch.

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