A Lumped Constant Complementary Filter for Frequency Ranges 157 to 212 MC and 225 to 400 MC

A complementary filter has been developed which permits using one antenna for simultaneous operation of two electronic equipments in the respective frequency ranges of 157 to 212 Mc and 225 to 400 Mc. It consists of lumped constant components, where distributed effects were considered in the design values of the lumped parameters chosen. Separate low and high pass units were also constructed. The filter has a VSWR less than 2:1 in its transmission regions. Its high pass section has a maximum insertion loss of 1.6 db at 225 Mc which remains less than 1 db from 234 to 400 Mc. There is more than 70 db attenuation at 212 Mc and more than 50 db at 157 Mc. The low pass section has maximum insertion loss of less than 1.9 db at 212 Mc which remains less than 1 db from 208 to 155 Mc. It has an attenuation of greater than 70 db at 225 Mc and more than 40 db at 400 Mc.