Switchable Filtering Circuit With Single- and Multi-Channel Operations

In this brief, we proposed a switchable filtering circuit with single- and multi-channel operations. It is a six-port circuit, consisting of three sections, namely, a switchable single- and quad-channel filtering circuit, a reconfigurable impedance matching network (IMN), and a single-pole double-throw (SPDT) switch. Two of the ports can be switched to satisfy the requirement of a time division duplexer sub-system, while other four ports can be reconfigured to transmit or receive signals in one channel or four channels. The presented switchable circuit can be utilized as the feeding network of a switchable directive and omni-directional antenna systems by using only directive antennas, while the omni-directional antenna can be eliminated. The design methods and experimental results of the presented switchable filtering circuits are given to verify the proposed ideas.