Single-pole double-throw switchable diplexer and single-pole quadruple-throw switchable quadplexer using capacitively loaded multicoupled line

Compact switchable diplexer and quadplexer are proposed using the capacitively loaded multicoupled line and the common resonator technique. The proposed single-pole double-throw (SPDT) switchable diplexer integrates the functions of SPDT radio frequency switch and bandpass filter, and each signal path can be independently synthesised using the insertion loss method. In addition, by a simple modification to the common resonator, a single-pole quadruple-throw switchable quadplexer can be achieved by the connection of two proposed SPDT switchable diplexers. Low-loss, compact size, good selectivity, and high-linearity are achieved.