Dual-Sense Circularly Polarized Antenna With a Dual-Coupled Line

This letter presents a dual-sense circularly polarized (CP) microstrip patch antenna with a dual-coupled line. The rectangular patch antenna operating in TM01 mode is utilized as a basic design, and a single-coupled line is introduced to excite the TM10 mode with a phase difference of 90°, generating CP operation. As different polarizations can be obtained by changing the position of the single-coupled line, a dual-coupled line is introduced to the rectangular patch antenna to excite two CP modes with different polarizations. The prototype of the dual-band dual-sense CP antenna is fabricated and measured. The measured results illustrate that the dual-sense CP antenna obtains a wide impedance bandwidth of 7.95% and dual axial ratio (AR) bandwidth of 0.33% for the left-hand circular polarization (LHCP) and 0.72% for the right-hand circular polarization (RHCP). Furthermore, the antenna has a wide 3 dB axial-ratio beamwidth and a small frequency ratio of 1.04.