5.5 m EME DISH

This dish was acquired as surplus from a antenna measurement range. The dish was originally used as the transmitter antenna on a 1100 m long antenna measurement range from 1 GHz to 8 GHz. It was dismantled and transported to my QTH. The center part of the dish is about 3 m in diameter and is surrounded by 8 segments to make the total diameter 5.5 m with a f/D of 0.37.

The dish when being dismantled for transportation from the original site. One of the eight outer segments is taken away.

The mount for the dish in place. The triangle at the top is the dish mount interface and elevation board. The azimuth axis is the center mast with a large chain drive at the bottom. Just behind the mount is a 6 m tower section (triangular 1 m side), used as support for mounting of the dish mount and dish. December 2005.

Feed support frame being assembled. Shown with one short leg and one mounting plate for attachment to the dish. The frame is 800 * 800 mm. April 2006

Feed support with W2IMU dual mode feed horn for 23 cm (circular polarization). April 2006

Feed for 23 cm and 13 cm when using the dish for tropo (linear polarization). April 2006

I plan to start with using the W2IMU dual mode feed horns for both 23 and 13 cm for EME. The dish will be heavy under illuminated, but the antenna temperature will be good. The gain will be affected by at least 1 dB. Next step will be to look into making a more optimal feed for this dish for 23 and 13 cm. For 70 cm EME an XE1XA loop feed will be tried (linear polarization). This feed will be used for 70 cm tropo as well.

August 7th 2006. The dish is now assembled and cleaned. Some of the 574 bolts that hold the parts together are still to be put in place.

September 17th 2006. All 574 bolts are now tightened! The final adjustment of the focal distance has also been made. The dish is then waiting to be cleaned and painted.


July 2008. The dish is now painted and ready for being put on the mount.                                               September 12th 2008. The XE1XA ring feed for 432 MHz is now tuned.

September 14th 2008.  The lifting aid is in place and ready to get into action.


September 14th 2008, 15:00. The 5.5 m dish is now in place on the Az / El mount. Cabling, elevation control power, elevation indication, elevation counter weight and the feed shall now be put in place.

 Photo: SM6GXV

November 1st 2008, 13:00. Measuring sun-noise on 23 cm (sun to cold sky >14.5 dB of excess noise at SFI=68). W2IMU dual mode feed with FHX35 LNA. A few minutes later nice CW and SSB echos were heard from the moon with about 360 W RF at the feed. The moon was only 4.5 degree above the horizon giving a lot of noise from the ground (ground to cold sky gave >4.5 dB excess noise). Moon was at apogee at the time.

The results were better than expected and still the best of all; I have a long list of things to do in order to improve the performance of the system! It will keep me busy for some time now.

CU off the moon on 23 cm!


Updated November 9, 2008.              http://www.2ingandlin.se/SM6FHZ.htm