Patent ID: 8358182

Claim:
A duplexer comprising: a dielectric substrate having a circuit-receiving surface and an opposite surface; a ground structure deposited on one of said circuit-receiving surface and said opposite surface; a first filter connectable to a first terminal and having a first frequency bandpass; a second filter connectable to a second terminal and having a second frequency bandpass different from said first frequency bandpass, said first filter and said second filter each having at least one filter section deposited on said circuit-receiving surface; and an uncovered coupling circuit connectable to a third terminal and deposited on said circuit-receiving surface between said first filter and said second filter, the coupling circuit being spaced apart from said first and second filter by a coupling gap and configured for electromagnetically coupling said first filter and said second filter together in order to electromagnetically couple a first quasi-transverse electromagnetic (TEM) wave signal having a first frequency within said first frequency bandpass between said uncovered coupling circuit and said first filter, and a second quasi-TEM wave signal having a second frequency within said second frequency bandpass between said uncovered coupling circuit and said second filter.