A Wideband CP Crossed Slot Antenna Using 1- λ Resonant Mode With Single Feeding

This communication proposes to use the 1-λ resonant mode of slot radiator with single feeding for bandwidth enhancement. The impedance of a simple slot radiator is studied using computer simulation. Since operating the slot radiator in the 1-λ resonant mode requires a longer slot length, a large square slot is used at both ends of the slot to reduce the required slot length. The results of the study are subsequently used to design a wideband circularly polarized (CP) crossed slot antenna (CSA) with single feeding. The CSA consists of two slot radiators having the same length and placed in a crossed shape, i.e., orthogonal positions. A single microstrip line with a via at the end is used to feed the CSA. By loading reactive elements with appropriate values on each slot near to the feed line, the two slots generate two linearly polarized electric fields with 90°-phase difference for CP operation. The CSA is studied and designed using simulation and measurement. Measured results show that the CSA has a wide impedance bandwidth of 1.52-3.44 GHz (1.92 GHz, 77.4%) and axial-ratio bandwidth of 1.73-3.01 GHz (1.28 GHz, 54%), much wider than the previous directional and bidirectional CSAs using single feeding.