In April 2025 I worked on my 76 GHz setup to measure sun and moon noise en Cs/gnd to see if I could be able to get a good performance

I am using a CAS120 Kathrein dish which I mounted on top of an Astronomical Sky watcher Gearbox

Then I needed to find the exact position of the focal point of the dish, I should be close to the feed bar but on 76 GHz this location is very critical.

I started the search for focus by using my hand above the feed bar and turn the antenna into the direction of the sun.

I found a spot illuminating my hand but this spot was not very clear and not good enough to find the exact focal point.

Then I put in several small mirrors in the dish to get better spots from the sunlight reflected by the dish.

In total I put in 7 small mirrors.

With that I used a piece of trespa at the position of the feed bar and turned the antenna to see if there would
be a point where the different spots would combine to a hot spot

First a picture with the spots not combined

Then a picture from the dish aimed at the sun with the best combination of the spots

Some pictures with the dish aimed at the sun but moving the trespa plate from forward to backward to find the best focus

Then I knew at what height above the feed bar the focal point should be and I could start making mechanical construction that the height
would fit to the transverter with pre amplifier and feedhorn

I made a construction using two trespa plates, one attached to the feed bar and the other attached to the transverter.
With this it should be possible to adjust the distance between the dish reflector and the feed focal point.

Now it was time to do the first measurements

At first I measured the Cs/gnd, I repeated the measurement several times and best value measured was 1.4 dB

Then it was time to do the first sun noise measurement and start to allign the focus distance

First measurement 7.6 dB

I increased the distance a little bit and measured again

Second measurement 6.8 dB

Then i decreased the distance a bit shorter than first measurement

Third measurement 7.7 dB

This is how I marked the different spacings

A bit further decreasing distance

Fourth measurement 8.0 dB

A bit further decreasing distance

Fifth Measurement 8.1 dB

5 different positions

I was heapy with this result and had to wait several hours to get a moon window

The measurement of moonnoise

Best value measured 0.65 dB.

This was a bit below expectation but I needed to check the moon temperature.
looking at VK3UM EME planner showed that the moon was quite cold at only 216 K, this explained the low value

After the measurements I tried to calculate the values I should be able to reach using the
EME Link Budget & Analysis Tool (1 - 300 GHz) from OE2IGL

                These values are very well fitting and I had reason to be happy with these results.