A stair-case structure loaded ZOR antenna for millimeter wave applications

In this paper, a compact stair-case multi-finger capacitive structure is proposed which is then loaded on to a patch antenna, to design a ZOR antenna for millimeter wave applications. From the band of millimeter wave, 30 GHz is selected as a resonating frequency of zeroth-order mode as it is suitable for applications like threat detection and standoff screening. An equivalent circuit of a unit cell is designed using composite right/left handed (CRLH) transmission line model. The metamaterial behaviour has been verified from dispersion diagram and vector electric field plot. Results of ZOR antenna is compared with that of the patch antenna designed for same resonating frequency operating in TM010 mode. Overall Antenna dimensions for ZOR mode comes out to be 0.8λ0 × 0.9λ0 × 0.08λ0 which is almost 60% of the TM010 mode antenna dimensions with almost similar characteristics. The design complexity of the proposed antenna is very less, as no vias are involved. Similarly, insertion of stair-case structure provides multiband characteristics with the advantage of tuning, which can be used for designing of multiband antennas.