Circularly Polarized Antenna With Reconfigurable Broadside and Conical Beams Facilitated by a Mode Switchable Feed Network

Abstract

A pattern-reconfigurable slot-augmented patch antenna is reported that radiates circularly-polarized (CP) fields and is switchable between a broadside and a conical radiating mode. Two novel design strategies are adopted to realize these advantageous performance characteristics. First, a mode switchable feed network which includes a set of eight L-probes was developed that facilitates the proper excitation of either the patch's TM11 or TM21 mode and yields symmetric radiation patterns. Second, their operating bands are made to overlap by augmenting this patch with an annular slot. Consequently, the radiation pattern is easily switched between the broadside and the conical mode within the overlapping operational bandwidths. A prototype was fabricated and tested. The measured results are in good agreement with their simulated values, verifying the design concepts. The measured operating bandwidth, 7.8% from 2.45 to 2.65 GHz, was determined from the overlap of the impedance and AR bandwidths for both modes. The measured realized gain values are stable for both radiating states within this operational bandwidth, the broadside (conical) peak value being 8.5 dBic (5.8 dBic). The CP pattern reconfigurability of this antenna with its favorable performance characteristics makes it an ideal candidate for many RFID and satellite communication applications.

Low‐profile circularly polarized microstrip patch antenna with pattern diversity

“…It causes the antenna to produce circularly polarized conical radiation pattern. It greatly simplifies the complexity of the antenna compared with the previous works …”

“…Various pattern diversity antennas with broadside and omnidirectional patterns are designed . The antennas in Refs.…”

“…In Refs. , circularly polarized antennas realize the reconfigurable broadside and conical beams by using a 90° phase‐shifted feed network with switches, thus, they suffer from complex structures, high profiles, and fabrication difficulties.…”

“…2 Various pattern diversity antennas with broadside and omnidirectional patterns are designed. [3][4][5][6][7][8][9][10][11][12][13][14][15] The antennas in Refs. 3-5 achieve pattern diversity by integrating antennas with different radiation patterns.…”

“…With four pairs of silts on the patch, the antenna achieves good circular polarization performance for both broadside and conical patterns on the planar structure. Compared with previous circular polarization pattern diversity antennas, [13][14][15] the proposed antenna has the merits of the low fabrication cost, simpler structure, and low-profile. Figure 1 shows the geometry of the proposed pattern diversity circularly polarized antenna.…”