Time to tune your antennas

[4wd]

9e 12.30, back 12.37

 

[RimaNTSS]

There was sun-outage experiments on different antennas today at Nijmegen. Do you recognized antennas and a backyard?

 

[Captain Jack]

Has to be Wim's.... He likes putting his dishes on a trolley.

 

[Trust]

Has to be Wim's.... He likes putting his dishes on a trolley.

Its only at the "Moonlander" because Rimants keeps coming to me so I dont have time to get it on the pole behind .

 

[Captain Jack]

What's that big dish behind? Neighbour's?

 

[Trust]

What's that big dish behind? Neighbour's?

Yep neighbour .
Its'not a big dish , big begins at 1.8 m , never seen it from behind but according to the feedarm connection to the dish , its a 1.2 m CM

 

[4wd]

13e

 

[RimaNTSS]

Even if it is overcast and rains, effect of sun-outage is maximum today (at my place). I turned antenna towards 4*W and monitored 10722H frequency for some time, taking data each 50 sec. , then made a graph for visibility.

 

[Captain Jack]

Sunny morning, so set up my phone to try and take some time lapse pictures of the sun hitting the dish.

 

[Captain Jack]

Here it is! Ignore the sheep invasion in the background....

I pause the video and check the timestamp on this site to see where the sun is at that point.

 

[RimaNTSS]

Did not show another screenshot of data I've got couple of days ago. Monitored 11958H @4,8* during outage time. Picture was not completely lost but little bit breaking up. Signal was measured once per 26 seconds (or something like that).

 

[RimaNTSS]

It is time again to dig up this topic. Will not repeat everything from very beginning, but it is great time to check our dishes. One of the great sources is THIS site.

 

[timo_w2s]

Haha, I was thinking about this thread just a couple of days ago as I looked at the sun shining on my dish.

 

[Captain Jack]

So... hmm... I am confused.

Where my dish is at the moment, I cannot lock a single* transponder from 55E. 12522 comes in at just over 7dB but no lock So, I thought I'd check signal footprint on the dish on this sunny Sunday morning...



Now, correct my if I am wrong, but would I be correct in assuming that I am getting around 2/3 of dish coverage? If that's the case, it would at least be equivalent to a 1m dish, maybe even 1.2m. So why am I getting worse signal than I expect? I haven't really monitored 55E since my Fibo 90cm went down at my old place last year, so I don't know if signal strength changed or what. I am getting nothing at all from 57E, where signal coverage looks thus:



Again, I would expect at least a blip of a signal but I am getting nothing... nada. So the question is, do trees 'radiate' some noise, which cause the signal to be worse than it would be otherwise if I was to cover the same area of the dish with some cardboard (or some other microwave blocking material)?

Sadly, the tree is an evergreen, which is apparently over 30 years old and has sentimental value to the neighbour, so no way that's going down. I will have to convince her to trim the apple tree a little, growing next to it, but it's not really causing any issues at the moment.

* OK, I am lying - I can lock 11550V, which is a data one at 7.7dB but... kind of pointless...

 

[s-band]

Now, correct my if I am wrong, but would I be correct in assuming that I am getting around 2/3 of dish coverage?

You will be getting a few dB excess noise from the tree. In total you may be losing 7-10dB. Try measuring the noise level on a clear channel and moving the dish away (preferably >20deg above horizon) so that it can not "see" the tree (or any signals). That will give you an idea of the ground noise

 

[Channel Hopper]

Again, I would expect at least a blip of a signal but I am getting nothing... nada. So the question is, do trees 'radiate' some noise, which cause the signal to be worse than it would be otherwise if I was to cover the same area of the dish with some cardboard (or some other microwave blocking material)?

Sadly, the tree is an evergreen, which is apparently over 30 years old and has sentimental value to the neighbour, so no way that's going down. I will have to convince her to trim the apple tree a little, growing next to it, but it's not really causing any issues at the moment.

* OK, I am lying - I can lock 11550V, which is a data one at 7.7dB but... kind of pointless...

Any foliage will 'radiate' some signal, though this will be more scatter from other sources nearby than the water molecules in the tree bark, trunk or leaves.

You could be slightly off the arc at this point of course, down either to the declination or north/south being ever so slightly out, or possibly the weight of the dish affecting the post foundation.

 

[blademedia]

55E is a hard lock for me with a 1.2 clear view the shading of the tree looks like the problem as you say pity the dish isn't 1/2ft further towards the field

 

[s-band]

Any foliage will 'radiate' some signal, though this will be more scatter from other sources nearby than the water molecules in the tree bark, trunk or leaves.

Trees seem quite close to an ideal black body as far as radiation is concerned. If your trees are at 290 deg K and your LNB+feed+side lobe noise figure is around 1dB then I think that you should see a variation of around 6dB between pointing the dish at clear sky and the ground (or trees). In this test I used some microwave absorber as the ground noise source. The trees were about 0.5dB quieter. See this post for some tests with the CM1.8

 

[aceb]

Surely she wouldn't miss a couple of branches off the side It actually looks very similar to my coverage of 66E, I've been tempted to move the mount 2ft to the southwest but can't bear the thought of mixing yet more concrete.

 

[blademedia]

Surely she wouldn't miss a couple of branches off the side It actually looks very similar to my coverage of 66E, I've been tempted to move the mount 2ft to the southwest but can't bear the thought of mixing yet more concrete.

I only get a few radio channels at 66E aim for 68.5/70.5 if you make the move