Design of circularly polarized terahertz antenna with superstrate (cover) layer

We present the design of a circularly polarized antenna operating at 996 GHz. The antenna meets the requirements demanded by security applications where the orientation of the hidden object might not be optimal from the detection viewpoint. In order to radiate high power, we integrated an LT GaAs photomixer into the antenna structure considering a matrix realization with an interdigital electrode, choke filters and a superstrate layer. Since a good impedance matching between the antenna and the photomixer is essential for radiating the high output power, we developed an equivalent model of the interdigital electrode (IDE) and computed its capacitance in order to precisely design the matching. The addition of a superstrate layer with a specific size will induce a significant effect on antenna performances. Particularly, the realized gain of the proposed antenna structure can be significantly increased.