We report on the design and construction of a prototype band pass filter using inductive-strips (E-plane planar circuits) based on electromagnetic-field simulations. We also report on the construction and characteristics of a prototype duplexer consisting of two band-pass filters-one each for the uplink and downlink-and a Y-shaped branch circuit. As a result of the experiment of duplexer, an insertion loss of about 3.1dB in a bandwidth of 195MHz for the uplink filter and an out-of-band attenuation of 50dB at 41.47GHz could be achieved. And an insertion loss of about 3.0dB in a bandwidth of 763MHz for the downlink filter and an out-of-band attenuation for the downlink filter of 59dB at 42.09GHz could be achieved.