A Metasurface based Dual Passband Filter with Sharp Rejection for L-band Applications

In this paper, a dual passband filter has been proposed with an extremely sharp rejection band between them incorporating metasurface (MS) structure in L-band. A highly rejecting stopband of 20 dB has been achieved at 1486 MHz between the two closely spaced passbands located at 1211 MHz and 1761 MHz respectively. The top metallic pattern of the unit cell of the proposed MS structure has been designed on the top of a 1 mm thick FR4 dielectric comprising two inverted L slots arranged along the principal diagonal together with two ring slots. It is confirmed from the field analyses that the ring slots offer the two closely spaced passbands while the two inverted L slots are responsible for strong transmission zero at the stop band. The proposed structure offers polarization insensitive response as well as very good stability for oblique incidence up to 45°. Being electrically ultra-thin and compact in nature, the proposed structure can find potential applications in space communication and radar navigational systems at L-band.