2.4 meter Prime Focus high quality dish performs worse than a 90 cm Chinese offset dish on Ku

[Cham]

I have a dual Inverto LNB and Raven feed horn (tapered type for offset dish) on a 120cm channelmaster dish, I found about average 1-2dB across the board increase from using a regular LNBF to the Inverto/feed horn combo. Marginal signals with the standard LNBF are solid 100% with the combo. I use this dish on 103W. Of course getting the feed horn positioned exactly at the focal point is critical to getting any dish reflector to work properly.

Regarding gain calculations, these are theoretical, and actual results will often differ due to frequency variations and noise factors. Gain is rarely flat across a particular band for a given antenna. Pointing close to the horizon or locating the antenna close to a noise (interference) source will cause lower signal/noise readings depending on the radiation pattern of the antenna and noise source. There are always some side-lobes in the gain pattern on even well built professional antenna assemblies.

I have always felt that offset Ku antenna types perform better for a particular size of reflector than a center feed type. The only theoretical difference should be the area the feed horn, mount assembly, and cables displace... but it seems there is more loss somewhere... maybe internal noise being reflected back to the LNB? Seems to be less of an issue lower in frequency (C-band). Anyway.. just my 2 cents worth.

 

[enb141]

Thanks for your advice Cham

 

[Brct203]

One more question:

According to the manual, this antenna should give 47.0 dBi gain at midband (+/- .2dB) and according to manual, a Chinese 90 cm should give 40.32 dBi @ 12.5 GHz.

So in other words if my 90 cm is giving mi -35 db, I should get -27 db (- 35 + 7 = -27) right?

Here are the links of the manuals of some Chinese antennas

https://www.multicominc.com/wp-content/uploads/MUL-90CM-KU-Satellite-Dish_N1.pdf

http://tele-audiovision.com/TELE-satellite-1101/man/svec.pdf

Just a thought... Can you clarify what it is that you are measuring? I don't have a meter or any way of measuring signals other than the Signal Quality indicator on my receiver, so i'm no expert on the topic, but I was wondering if maybe the gain of the LNB is a factor in your measurements. I'm guessing that C/N is what we're interested in, right?

Have you hooked up a receiver to the Prodelin and checked what the quality looks like from that perspective?

 

[enb141]

Just a thought... Can you clarify what it is that you are measuring? I don't have a meter or any way of measuring signals other than the Signal Quality indicator on my receiver, so i'm no expert on the topic, but I was wondering if maybe the gain of the LNB is a factor in your measurements. I'm guessing that C/N is what we're interested in, right?

Have you hooked up a receiver to the Prodelin and checked what the quality looks like from that perspective?

I'm using a PCI express satellite turner card with EBSPro, that software shows me the db I'm getting.

 

[khaled cr7]

Hi

I have dish DH 3 meter
And there it is lnb ku
What is the feedhorn Number of ring Suitable for this dish

The size of the dish is 3 meters
Net Size 286
Depth 56
Focal length 91 cm