Circularly polarized annular slot antenna with switchable frequency

Abstract

A design for frequency reconfigurable annular slot antennas with circular polarization (CP) is described.The slot antenna is excited with a shorted microstrip line through coupling, and one varactor diode placed on the slot is used to generate CP radiation. By controlling the dc bias of the varactor, the CP operating frequency of the slot antenna can be switched between two frequencies with a frequency ratio of about 1.6; moreover, the antenna operating at each CP frequency has a return loss of less than 10 dB and the broadside radiation with a peak gain of higher than 3 dB. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1115–1118, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27509

Circularly Polarized Wideband-to-Narrowband Switchable Antenna

“…The antenna can support both RHCP and LHCP operations in single wideband (1.6-2.56 GHz) and dual-band (1.25/2.43 GHz) modes by using four PIN diodes locating in the links and the feed lines of the two ports. Also, in [17], a frequency reconfigurable circularly polarized slot antenna is proposed. The antenna consists of annular slot fed by a shorted microstrip line through coupling.…”

“…The antenna can be reconfigured between two operating frequencies of 1.88 GHz with bandwidth ratio of 2.7% and 2.88 GHz with bandwidth ratio of 3.3% by controlling the dc voltage of the varactor placed on the slot. The antennas in [16] and [17] are circularly polarized at all modes, but the wideband mode bandwidth isn't sufficient for the sensing process of the cognitive radio devices.…”

Double triangular monopole-like antenna with reconfigurable single/dual-wideband circular polarization

“…In references, many methods are reviewed to design the printed CP antennas with different shapes of patches, feeds or radiating slots for dual‐band or broad‐band CP. A multi‐resonant CP antenna is also useful to reduce the total size . The conventional single‐fed CP antennas typically have a relatively narrow CP bandwidth (BW) .…”

“…A multi-resonant CP antenna is also useful to reduce the total size. 7 The conventional single-fed CP antennas typically have a relatively narrow CP bandwidth (BW). 8 For a dual-fed design, different power dividers are required to obtain the desired orthogonal polarizations and so the broad-band CP.…”