- Passive repeater
A passive radio link deflection, or passive repeater is a plant for the implementation of a
microwave link , in which because of an obstacle in the signal path no direct line of sight microwave link is possible. It has the advantage over the installation of amicrowave radio relay station with active components, that at the place of the installation no electricity supply is required and that no further frequencies are needed (atrepeater stations with active components usually different frequencies for reception and transmission are used, in order to prevent feedbacks). The corresponding disadvantage is that the returned signal is significantly weaker.Passive radio relay link defelection systems in the vertical level can be realized by receiving the signal with a
parabolic antenna and leading it through awaveguide to a second parabolic antenna, where it is radiated. For passivemicrowave radio relay link deflections in the horizontal plane, flat surfaces of metallic material are used, arranged so that the angle of incoming beam corresponds to the angle of the outcoming signal. The resulting structure resembles a billboard. For small deflection angles, cavity prisms can be used.Similar systems are used also occasionally for
TV relay transmitter s or astunnel transmitter . Here aYagi antenna receives the signal of the transmitter and supplies it by way of acoaxial cable to a second antenna.External links
* [http://long-lines.net/places-routes/Thurmont_repeater/index.html Microwave passive repeater in Maryland]
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