A two terminal electronic filter network is provided for connection across TV antenna input terminals to reduce interference from noncommercial FM radio stations operating within a frequency band near the TV channel 6 frequency band. The two terminal electronic filter circuit which exhibits a rapid change...http://www.google.com.hk/patents/US4287602?utm_source=gb-gplus-share專利 US4287602 - Rejection filter to remove TV channel 6 and FM radio interference
