C-band Linear/Circular Orthomode Feed Modification (1 Viewer)

Status
Please reply by conversation.

ACRadio

SatelliteGuys Pro
Apr 25, 2006
794
0
Near Asheville NC

Attachments

  • IMG_5842.JPG
    IMG_5842.JPG
    630.1 KB · Views: 311
  • IMG_5843.JPG
    IMG_5843.JPG
    455.7 KB · Views: 315
  • IMG_5844.JPG
    IMG_5844.JPG
    544.4 KB · Views: 344

ACRadio

SatelliteGuys Pro
Apr 25, 2006
794
0
Near Asheville NC
is that 2 chaparal orthos in the pic? im assuming a dielectric is needed in one ?

crackt out,.

Yep...2 Chaparral orthos with a plate in the upper one. This dish has a left hand mounted actuators so the linear can see a bit farther west and the circular can see a bit farther East. I can see down to Express AM44 at 11 West.
 

greenguy

SatelliteGuys Pro
Mar 18, 2010
213
0
Home Ground. . .
Yep...2 Chaparral orthos with a plate in the upper one. This dish has a left hand mounted actuators so the linear can see a bit farther west and the circular can see a bit farther East. I can see down to Express AM44 at 11 West.

will the chaparrel corotor II wideband feed perform the same way as your setup?
 

ACRadio

SatelliteGuys Pro
Apr 25, 2006
794
0
Near Asheville NC
will the chaparrel corotor II wideband feed perform the same way as your setup?
I wouldn't know as I have never played with a wideband Corotor. I deleted the message above this because I thought you were talking about mounting 2 wideband Corotors in siamese configuration...
 

crackt

SatelliteGuys Pro
Feb 24, 2007
1,000
1
101w up north.
will the chaparrel corotor II wideband feed perform the same way as your setup?

the corotor wideband feed is a different solution to the problem the siamese ortho setup solves. the main differences between it and the siamese are...

- the siamese setup can feed more than one reciever at a time.
- the wideband corotor needs a reciever capable of setting 4 polarizer positions.

umm and i think pendragon has stated that an orthomode feed performs better than a corotor feed. i thinks thats about all i can think of.

crackt out,.
 

greenguy

SatelliteGuys Pro
Mar 18, 2010
213
0
Home Ground. . .
the corotor wideband feed is a different solution to the problem the siamese ortho setup solves. the main differences between it and the siamese are...

- the siamese setup can feed more than one reciever at a time.
- the wideband corotor needs a reciever capable of setting 4 polarizer positions.

umm and i think pendragon has stated that an orthomode feed performs better than a corotor feed. i thinks thats about all i can think of.

crackt out,.

ok thanks. . .why i ask is because im usin the chaparrel wideband feed and it performs 'ok' i would say 'ok' is because i have nothing to compare it to.
i dont need it to hook to a million receivers as its only me who will watch anything on the bud :D, im also have 2 pansats and a 4d receiver which can work my servo motor.

as for performin better, what difference would i see if i where to use one of this bad boy feeds?

thanks guys
 

pendragon

Thread Starter
SatelliteGuys Pro
Oct 13, 2008
1,100
63
as for performin better, what difference would i see if i where to use one of this bad boy feeds?

I've not seen a direct performance shoot-out between these feeds, however I've corresponded publicly and privately with a number of people who have done some form of testing between the available C-band feeds. The composite of this and published specifications leads at best to a coarse estimate of the relative performance of a wideband corotor with the dielectric inserted vs. the two single ortho feeds I used.

For the linear side, a wideband corotor without a dielectric plate delivers about 1 dB less CNR than single linear ortho feed. Inserting the plate causes a further 0.5-1 dB loss. On the circular side, a high-end circular feed like the ADL will outperform a single ortho with a dielectric plate by about 1 dB, and and that will outperform a corotor with a plate by another 1 dB. The losses are therefore between 1-2 dB for both sets of polarization.

Translated into other terms, let's say one has a 10' dish with a corotor plus a dielectric plate. A 1 dB loss means the dish will perform in CNR the same as a 8' dish with a single ortho feed. A 2 dB loss means the dish will perform in CNR the same as a 6.5' dish with a single ortho feed. CNR is important for C-band reception, but it isn't everything. Separating an adjacent orbital position 2 degrees away is also important and a 10' dish will do this the same regardless of the feeds listed here. Whether CNR is critical to your needs depends a lot on your viewing preferences. If you're after weak, near the horizon, high rate, high FEC and/or DVB-S2 signals, a better feed can make a big difference.
 

greenguy

SatelliteGuys Pro
Mar 18, 2010
213
0
Home Ground. . .
ah ok. . .thanks guy, im not sure what CNR is but i will look it up, so far my wide band feed works and gets me the TPs im after with high quality where possible, so im happy. ;)
 
Status
Please reply by conversation.

Users who are viewing this thread

Users Who Are Viewing This Thread (Total: 0, Members: 0, Guests: 0)

Top