Shortwave relay station

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ALLISS antenna as viewed underneath

A shortwave relay station typically consists of a transmitter building (or transmitter hall) and one or more HRS type antennas. Some relay stations (that operate at 100 kw or less) that only serve a local region (within 1500 kms) may use Log Periodic Horizontal arrays and not HR Type antennas.

[edit] Variations in design

One and only one broadcasting technology couples all of the components of a traditional shortwave relay station into one unit: the ALLISS module. For persons totally unfamiliar with the concepts of how shortwave relay stations operate this design may be the most understandable.

The ALLISS module is a fully rotatable antenna system for high power (typically 500 kW only) shortwave radio broadcasting -- it essentially is a self contained shortwave relay station.

Most of the world's shortwave relay stations don't use this technology, due to its cost (15m EUR per ALLISS module: Transmitter + Antenna + Automation equipment).

[edit] FAQ

[edit] How relay stations operate

• 20 hours per day
• generally 360 days per year
• consuming from 250 kilowatts (kW) to 10 megawatts (MW)
• broadcast times and frequencies are under ITU regulation

[edit] How relay stations are designed

• Road access (fairly universal)
• HVAC mains access building or transformer
• Staff quarters (if not automated)
• Incoming audio processing centre
• Transmitter hall (50 kW, 100 kW, 250 kW, 300 kW, 500 kW shortwave transmitter)
• Switch matrix (but not used by ALLISS)
• Bauns (but their use is not universal)
• Feeder lines (coax, open feeder line)
• HRS-type antennas
• In parts of the developing world log-periodic (horizontal) antennas are used to provide less directional gain to a target area.

[edit] Where the broadcast programs go

• generally to target areas that are more than 300 km from the transmitter site
• most shortwave relay station target areas are 1500 km to 3500 km from the transmitter site

[edit] Historical innovations

In the IEEE Book series "The History of International Broadcasting" (Volume I) it is pointed out that the German propaganda ministry had mobile shortwave relay stations during WWII. These mobile relay stations consisted of a generator truck, transmitter truck and an antenna truck.

• It is assumed that these mobile relay stations were in use from about 1940 onwards.
• It is assumed that the antennas used where Rhombic, but could have been Log Periodic.
• It is assumed that the transmitter power was 50kw, and that these transmitters required a full size truck.
• It is assumed that the relay stations were moved every two or three days, to prevent HFDF.
• It is assumed that no stations were ever destroyed via aircraft, but that many would have been captured during 1945 by both the US, British and Russian forces.

Technical notes

• In order for the relay network to get its audio feeds, the PTT constructed concrete bunker telephonic termination points throughout the German state.
• Only RIZ (Radio Industry Zagreb) produces mobile shortwave transmitters in the current post-Cold War era. RIZ's designs are clearly not inspired by the German wartime innovation, as they are based around standard shipping containers.
• RIZ's portable designs are meant to be portable temporary replacement transmitters, not truly mobile shortwave relay stations.
• The only kinds of antennas that are both mobile and directive and also suitable for this kind of relay station design are the Rhombic and Log Periodic antenna types.

[edit] Graphic examples

Example of a theoretical shortwave relay station in central Canada, single antenna with single transmitter

[edit] Actual configurations: NAUEN