Radiation Properties of Wideband Multi-Ring Microstrip Antennas Fed by an L-Probe for Single- and Dual-Band Operations

Yuki KIMURA  Sakuyoshi SAITO  Yuichi KIMURA  Tatsuya FUKUNAGA  

IEICE TRANSACTIONS on Communications   Vol.E104-B    No.7    pp.858-864
Publication Date: 2021/07/01
Publicized: 2021/01/08
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2020EBP3129
Type of Manuscript: PAPER
Category: Antennas and Propagation
multi-ring microstrip antenna,  planar antenna,  wideband,  multiband,  L-probe,  

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This paper presents the design and measurement of wideband multi-ring microstrip antennas fed by an L-probe for single- and dual-band operation. The proposed antennas consist of one or two square ring patches and an L-probe arranged in a multi-layered dielectric substrate. By using a thick substrate for the L-probe and optimizing the distances between the L-probe and the patches, wideband performance is successfully achieved. The optimal substrate thickness of the L-probe and patches to obtain good wideband performance were determined, and prototype antennas for single- and dual-band operation were fabricated and tested. The measured fractional bandwidths corresponding to reflection coefficients below -10dB were 46.1% for the single-band antenna and 20.3% and 15.7% for the dual-band antenna. The measured gains of the test antennas in the above bandwidths were 0-6.9dBi for the single-band antenna and 3.0-8.6dBi for the dual-band antenna. Although the E-plane radiation patterns were slightly tilted against the frequency, stable broadside radiation was confirmed. The proposed antennas exhibited excellent performance as wideband planar antennas for single- and dual-band operation. The proposed wideband antennas can be easily extended to a dual linearly polarized antenna by using another L-probe in the orthogonal position.