Circularly Polarized Leaky-Wave Antennas Based on Periodically Arranged Rotated Right-Angle Triangular Microstrip Patches

In this article, a scheme to realize the circularly polarized (CP) periodic leaky-wave antennas (p-LWAs) is prosed. A single-row model and a dual-row model are presented based on the series-fed periodically arranged rotated right-angle triangular (RAT) microstrip patches. For either of the two models, the antenna unit of one period occupies four RAT microstrip patches and the units are arranged repetitively on one side or on both sides of a transmission line. The open-stopband (OSB) is eliminated by adjusting the distances between the patches in each unit. The single-row model with 12 units on one side of a transmission line achieves a main beam sweeping angle range of 96° ( $-{\mathrm {56}}^{\circ }$ , $- {\mathrm {40}}^{\circ }$ ). The model realizes the left-hand (LH) circular polarization as the main beam is scanning continually from $-{\mathrm {19}}^{\circ }$ to 22°. The dual-row model includes 20 units of a different form of the rotated RAT microstrip patches arranged on both sides of a transmission line. The main beam is able to scan from $-{\mathrm {40}}^{\circ }$ to 35° while the antenna is radiating. The model realizes the LH circular polarization while the main beam is scanning from $-{\mathrm {18}}^{\circ }$ to 13°. The proposed two models can both realize circular polarization and continual beam scanning across the broadside.