144 MHz EME station and antenna

EME Equipment

Yaesu FT-847sspa forfra
HA8ET preamp
Dual yagi model PA144-6-2
Yaesu FT-8471 kW SSPAHA8ET Preamp 2 x 6 element yagi (2 m boom)Sequencer

EME Station Configuration

My EME station is pictured below in fig. 1. The power splitter, the preamp, and Relay2 are mounted in the mast close to the antenna. The SSPA, the PSU, the sequencer, and Relay1 are in the radio room. 

The SSPA is connected to the antenna using 22 meters of Ecoflex 15 low-loss coax cable. The cable loss at 144 MHz is 0.75 dB and this equals 160 W when running 1 kW. Remaining cables are standard coax cables. Relay2 is a high-power coax-relay. 

EME station layout
Fig. 1. EME Station Configuration.

EME antennas (ver. 1) - planned

I've planned a 2 x 8 element yagi array with elevation. The antennas will be vertically polarizedEach 8-element antenna has 11 dBd gain and the boom length is 3.8 m. A pair of these antennas would provide 14 dBd gain. I will be able to benefit from long operating hours since the array will point at the Moon as long as it is above the horizon. Elevation also reduces terrestial noise which is strongest when the antenna array is pointing at the horizon. 

EME antennas (ver. 2) - realized

December 2016. I've reviewed my antenna design. The first draft was 2 x 8 element yagis. It would require a 3 meter cross-boom made of steel tube. This kind of boom would be too heavy for my KR-550 rotor.  

My new plan is using a 2 meter long ash tree cross-boom and fit 2 x 6 element yagis on the boom. This array will have less weight, and the wind resistance will be low. It will be easier for the KR-550 rotor to handle. The two yagis will be PA144-6-2 from the company Dual (YU1CF). Each antenna has 9.2 dBd gain and a pair will provide about 12 dBd gain. This gain is below the figure set by DK3QN Klaus. He recommends minimum 15 dBd antenna gain for EME on his EME page. I may add another pair of 6-element yagis later increasing the gain to 15 dBd.

2x6 are up
Fig. 2. EME antennas for 144 MHz (2017-03-24).

OZ1BXM Lars on roof
Fig. 3. OZ1BXM on the roof (photo by XYL).

Page updated 09-April-2017 by Lars Petersen, OZ1BXM.