Friday, 27 May 2011

The Mighty VHF Radar

It's Friday and time to end the week with an interesting picture. This time we will feature the mighty EISCAT VHF incoherent scatter radar. If you have any interesting, beautiful, inspiring photos or graphs you want to share, please let us know and they will be included in a future Friday image feature.

The VHF radar, or simply the VHF as it is known, is the biggest of the EISCAT radars. It is located at Ramfjordmoen near Tromsø, Norway, at 69° 35'11"N, 19° 13'38" E. It is co-located with the transmitter of the tri-static EISCAT UHF radar.

The VHF is huge: its shape is a parabolic cyclinder, which is 120 m wide and 40 m high. It consists of four panels, each of which is 30 m wide. In the photo above, the westernmost panel is upright, i.e. it's pointing northward, while the other three panels are tilted back so that they point to zenith. It takes typically about 20 min for the huge electrical motors to tilt the antenna by 90°.

The photo was taken from what is called the feeder bridge. It features a total of 128 crossed dipoles for transmission and reception mounted on the outside of a fully-enclosed hallway big enough to walk around in. These dipoles are connected by coaxial cables and high-power wave guides to the transmitter and receiver systems. The transmitter is a 1.6-MW klystron, and the radar operates in the frequency range of 222.8 to 225.4 MHz.

Technical specifications as well as the locations of all EISCAT radars are available on the EISCAT website.

Have a good weekend everyone!

Photo: Thomas Ulich.

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