A Dual Band Dual Sense Circularly Polarised Single Feed Microstrip Patch Antenna

A novel and compact dual band dual sense circularly polarized microstrip patch antenna with single coaxial feed has been reported in the present work. The key idea of generating dual band circular polarisation (CP) is the integration of a square patch with corner truncation and a smaller concentric circular patch with double slits. The first resonance is provided by the larger patch whose corner truncation generates two orthogonal modes. The inner patch controls the higher-order resonance with the CP contributed by two narrow slits. The higher order resonating frequency can be monitored by controlling the dimensions of the circle and the slits. The antenna provides the CP in two orthogonal planes with two different sense of polarisation. The lower order CP is of left-handed orientation, whereas the higher order shows right-handed polarization. The cross-polarization level is also found to be very low.