Single- and Dual-Polarized Slot and Patch Antennas with Wide Tuning Ranges.

[摘要] Frequency- and polarization-agile antennas are of great interest for multi-function, software-defined, and cognitive radios.Frequency tuning over an octave is challenging because the radiation conductance changes as the antennas are tuned.In this work, single- and dual-polarized antennas are tuned over frequency ranges of up to 2:1 and 1.7:1, respectively, while remaining impedance matched.The impedance match over tuning is maintained by a properly chosen reactive element in series with the antenna.Both polarizations of the dual-polarized antennas are tuned independently—enabling either simultaneous frequency- and polarization-agility, or operation at two independent frequencies on orthogonal polarizations.First, the tunability of the slot-ring antenna is demonstrated with fixed-capacitor loading, and then, single and dual-polarized slot-ring antennas are tuned from 0.95 – 1.8 GHz and 0.93 – 1.6 GHz, respectively, using varactor diodes.Microstrip reactive loads are developed to maintain >20 dB port-to-port isolation over most of the tuning range of the dual-polarized antenna.This may be the first dual-polarized tunable antenna with independent control of both polarizations over a 1.7:1 frequency range.Single-sided radiation is desirable for many applications, and varactor-tuned cavity-backed slots are investigated for this purpose.A shallow cavity-backed slot is tuned from 1.0 to 1.9 GHz with <-20 dB return loss.The antenna operates either in free-space or conformally mounted with minimal change in input impedance.Finally, a dual-polarized cavity-backed patch antenna is tuned from 0.6 – 1 GHz.Differential feeds are employed to achieve >30 dB port-to-port isolation (differential-differential mode) over the tuning range, and the measured cross-polarization level at 0.65, 0.8, and 0.95 GHz is <-25 dB.This may be the first demonstration of dual-polarized independent tuning over a 1.7:1 frequency range with single-sided radiation.

[发布机构] University of Michigan

[效力级别] Dual-polarized Antennas

[关键词] Reconfigurable Antennas;Dual-polarized Antennas;Slot Antennas;Patch Antennas;Tunable Antennas;Antennas for Software-defined and Cognitive Radio;Electrical Engineering;Engineering;Science;Electrical Engineering