Ultra-short wave transmitter
An ultra-short wave transmitter is a transmission system for the generation of electromagnetic ultra-short waves (VHF) with a carrier frequency of 30 MHz to 300 MHz, corresponding to wavelengths between ten meters and one meter. In 1925 the world's first VHF transmission took place between Jena and Kahla by Abraham Esau .
To broadcast FM radio is frequency modulation used. The emphasis used in European VHF broadcasting when transmitting has a time constant of 50 µs, which results in a cutoff frequency of 3.2 kHz. In the USA, on the other hand, “FM radio” has a time constant of 75 µs.
In mobile systems, vertically polarized antennas are used as transmitting antennas , and in stationary systems mostly horizontally polarized antennas . These can be implemented as a dipole , cross dipole , slot radiator, butterfly antenna or dipole field.
The operation of VHF transmission systems in Germany is controlled by the Federal Network Agency . With a few exceptions, the transmission systems were operated by the provider Media Broadcast until 2013 . Since there was a dispute over fee increases through the media broadcast, some private local radio stations switched to the provider Uplink Network .
Since February 2006, the operation of so-called mini transmitters (also: FM transmitters) in the VHF band (Band II) with a short range of a few meters with up to 50 nW ERP for private purposes has been permitted in Germany, e.g. B. to transmit the signals of an MP3 player to the car radio.
- Stephan Munder: UPLINK NETWORK GmbH takes over parts of the radio NRW network. In: radioWOCHE - Current radio news, FM news, digital radio news and radio jobs. May 18, 2016, accessed May 18, 2016 .
- Order 07/2006: General allocation of frequencies in the frequency ranges 87.5-108 MHz, 863-865 MHz and 1795-1800 MHz for wireless audio radio applications, limited to 31.12.2016. (PDF; 19 kB) Federal Network Agency, February 8, 2006, archived from the original on September 27, 2007 ; Retrieved February 14, 2009 .