A miniaturized dielectric monoblock duplexer matched by the buried impedance transforming circuit

A dielectric monoblock duplexer as surface mount device is realized by using the stepped impedance resonators and the buried impedance transforming circuit. The RF leakage is suppressed because the whole outside wall of the filter is covered with plating electrode. The volume of the trial filter for 800 MHz mobile telephone terminal is less than 3.9 cm/sup 3/. The insertion loss and attenuation of transmitting filter are 1.6 dB and 53 dB, and those of receiving filter are 2.3 dB and 56 dB.<>