Unidirectional AMC reflector backed L-band annular slot antenna

This paper presents an artificial magnetic conductor (AMC) reflector backed low-profile annular slot-antenna with unidirectional radiation operating at the L band (1-2 GHz). The proposed antenna comprises of an FR4 substrate with a square shaped annular slot on one side and a feed element on the other side. The intrinsically bidirectional radiation of the slot antenna is made unidirectional by backing it with an AMC surface. An AMC has an added advantage because it can be kept closer to the radiating structure without distorting its antenna properties compared to the traditional perfect electric conductor (PEC) reflector, thus resulting in a low antenna profile. Three different types of AMC unit cells on grounded Rogers 3010 substrate, namely square patch, jerusalem cross and ring have been compared as back reflectors for this purpose. An overall antenna volume of 0.6 λ₀ × 0.6 λ₀ × 0.1222 λ₀ at 1.5 GHz has been achieved using an AMC backed reflector for a close separation of ~0.1 λ₀ between the annular slot radiator and the AMC reflector surface.