Method of constructing a composite receiving band filter

摘要

In a radio transmission/receiving device in which the same communication frequency band is used for transmission and receiving modes, a low pass filter for preventing higher harmonics is arranged between an antenna and a transmission circuit under the transmission mode and a band filter for band selection is arranged between the antenna and a receiving circuit under the receiving mode, whereby a reduction of production costs of the system is achieved at by reducing the number of elements required for the band filter.