Self‐isolated quadruplexing SIW antenna with extremely low frequency ratio for C‐band applications

Abstract

In this letter, an substrate integrated waveguide ‐based self‐quadplexing antenna based on a modified Jerusalem cross‐shaped slot is presented. By introducing different lengths of the slots of Jerusalem cross, the antenna operates at four different closely spaced resonant frequencies 4.08, 4.37, 4.61, and 4.97 GHz. The proposed quadplexer antenna achieved a minimum port isolation of 20 dB between any two ports with an extremely low frequency ratio of 1.2. The quadplexer antenna has unidirectional radiation pattern and independent frequency tunability characteristics with a gain of 6.88, 6.51, 7.03, and 7.12 dBi, at corresponding resonant frequencies and a compact size of 0.142, where 0 is the free space wavelength at the lowest resonant frequency. The proposed antenna is suitable for C‐band multiplexing applications.