| 摘要 |
<p>A radio frequency signal folding-back transmitting/receiving circuit for use with a radio transmitting/receiving apparatus is disclosed, that comprises a signal folding-back means for folding back a transmission signal of a local station to a radio frequency signal line of a receiver of the local station through a directional coupler, a first band-pass filter for allowing a reception signal that is output from an opposite station to pass, a second band-pass filter, connected to the first band-pass filter in parallel, for allowing a transmission signal whose frequency is different from the frequency of the reception signal to pass, and a selecting means for selecting the second band-pass filter when a radio frequency signal folding-back test is performed. <IMAGE></p> |
