It is therefore ideal for use in diplexers. These forms are useful in the design of diplexers and multiplexers. Applications include suppressing the harmonic output of transmitters and the design of wide-band diplexers. Robertson fabricated circuits for diplexers and couplers and coined the term "finline". Such devices include impedance matching components, directional couplers, and diplexers. The plan is economical if the diplexers cost less than running a second cable. Diplexers are not used at VLF transmitters. A satellite earth station may have multiple diplexers connected to a multi-band antenna feeder. Many other large UHF-/VHF-transmitters use diplexers. Diplexers are also used at medium wave broadcasting stations. Diplexers may be used as a back-up device. Diplexers are also used for non-broadcast applications such as amateur radio.