Compact microstrip and CPW duplexers using complementary and conventional logarithmic spiral resonators

Recently, we proposed a super compact metamaterial particle called logarithmic spiral resonators (LSRs) and used them in microwave filter applications. The stopband property in LSRs is due to the resonant behavior of individual elements and not due to the periodicity. Therefore LSR can generate a stopband even with one element. In this paper we study the applications of complementary and conventional LSRs in microstrip and coplanar waveguide (CPW) duplexer designs, respectively. Being the dual counterpart of complementary LSRs (CLSRs), the conventional LSRs are investigated here for the first time.