This paper presents a novel dual band, dual Circularly Polarized (CP) hybrid antenna consisting of a microstrip patch radiator and semi-hexagonal half mode substrate integrated waveguide (HMSIW) cavity. The hexagonal HMSIW cavity operates at its fundamental TM010 mode and excites two rectangular radiating patches with different sizes to provide multiband operation. An inclined slot with suitable size and position is placed on top of each patch to provide CP with different types including right-handed CP (RHCP) wave at the first band and a lefthanded CP (LHCP) wave for the other band. Antenna structure is numerically simulated using High Frequency Simulator Structure Simulator (HFSS) and results including reflection coefficient, axial ratio (AR), and radiation patterns are reported. Moreover, a linear array of two elements of the proposed hybrid antenna is designed and simulated. A prototype of the proposed single element and two elements array is made and successfully tested. The measured results show that for the proposed two elements array 3 dB AR bandwidth and peak gain for the low- and the high-band are 1%, 9.2 dBi and 3.1%, 8.8 dBi respectively, which agrees well with those obtained by simulation.

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