Question on a Dual C/ku Feedhorn? (1 Viewer)

Status
Please reply by conversation.

voomvoom

Thread Starter
SatelliteGuys Master
Lifetime Supporter
May 18, 2004
6,659
27
Lizella, Georgia Republic
I was reading in a thread in the FTA section and the thread was "What is the ultimate FTA set up???" by cablewithaview. In this thread a post by digiblur says:
A solid 15 footer with CBand, Linear KU, and Circular LNB's. Receivers attached would be able to receive HD, 4:2:2, 8PSK, analog, 4DTV, AC3, etc. And of course no trees or obstructions to the south. And while you are at it, the ability to track inclined orbit sats.
I'm sure these dual C/ku feedhorns are intended for the ability to get H and V on multiple receivers. It made me think. If I were to get one of these feedhorns? Could I put a Linear lnb on one side and a Circular lnb on the other side? Would it work? I think it would. What do you think? Most people probably (my opinion) use one or the other and swap them out occassionally, using regular feedhorns. This would allow you to have both on the dish and in a prime focus possition. Any thoughts?

Al
 

mikekohl

Prehistoric Satellite Guru
Supporting Founder
Jun 4, 2004
762
153
Montfort, Wisconsin
LNBs have no polarity....they are simply LNBs.

Feedhorns can be either linear or circular.

LNBFs can also be either; a dielectric plate is usually the cheap shortcut
used to achieve circular, such as on DBS satellites.

A common 4 port feed that is linear C (2 ports) and linear Ku (2 ports)
is the ADL RP-3 2 plus 2, which has several variations.
Most offered unit is linear on both C and Ku-band.
Astrotel also makes a like unit.

Go to www.adlfeed.com for a full listing of feedhorn configurations,
or drop me a line at globalcm@mhtc.net if you have any specific questions
on what might be available.
 

voomvoom

Thread Starter
SatelliteGuys Master
Lifetime Supporter
May 18, 2004
6,659
27
Lizella, Georgia Republic
mikekohl said:
LNBs have no polarity....they are simply LNBs.

Feedhorns can be either linear or circular.

LNBFs can also be either; a dielectric plate is usually the cheap shortcut
used to achieve circular, such as on DBS satellites.
Mike, I know lnb's don't have polarity. I was refering to the feed horn, one of the lnb positions (of the 2) is 90 degrees different from the other. I assume that could make one H while the other would be V, or visa versa.
This I didn't know,"Feedhorns can be either linear or circular." I did know they had a regular (to me) and a wideband (used for circular, I guess), maybe that is linear and circular. My question was why can't I have one of each (linear and circular) lnb's on this type feedhorn? And, would it work?
I had forgotten about the dielectric plate's.

So, I'm assuming, you are saying I can't put a linear lnb and a circular lnb, on one of these type feedhorns. That's what I wanted to know. Thanks.

Al
 

tdti1

SatelliteGuys Pro
Nov 23, 2004
2,318
1
Montreal, QC
I have a wideband feed (C-band linear/circular and Ku-band linear) I added a dbs feed by drilling a hole in my scalar ring to get the circular Ku-band, though I do not use the dbs part of it, I guess I did it to see it be done, I don't even have a coax coming in from it, to test it I just swapped my other coax but ended up putting it back, only thing about a setup like mine is the dbs satellites are off because it is off centre or the reflector, and so I would need to bump the dish a bit off to pick it up.

I may run all new cable one day, and a extra one for the dbs, but I get eveything I want now, I just need a bigger dish to have more fun.
 

voomvoom

Thread Starter
SatelliteGuys Master
Lifetime Supporter
May 18, 2004
6,659
27
Lizella, Georgia Republic
tdti1 said:
only thing about a setup like mine is the dbs satellites are off because it is off centre or the reflector, and so I would need to bump the dish a bit off to pick it up.
This is what I'm sort of getting at. With a feedhorn with 2 C lnb's and 2 ku lnb's, they would be centered. If you could only use both a circular and a linear? That would be great. Apparently it won't work.

Al

I might get one and see if I can make a believer out of me? I'm an idiot? Can't help myself and others give in/up.....
 

tdti1

SatelliteGuys Pro
Nov 23, 2004
2,318
1
Montreal, QC
voomvoom said:
This is what I'm sort of getting at. With a feedhorn with 2 C lnb's and 2 ku lnb's, they would be centered. If you could only use both a circular and a linear? That would be great. Apparently it won't work.

Al

I might get one and see if I can make a believer out of me? I'm an idiot? Can't help myself and others give in/up.....

Never seen a feed with both h/v and l/r for c/ku.
 

voomvoom

Thread Starter
SatelliteGuys Master
Lifetime Supporter
May 18, 2004
6,659
27
Lizella, Georgia Republic
tdti1 said:
Never seen a feed with both h/v and l/r for c/ku.
I can't say I have either, but I was thinking the way they bolt, if they fit, why wouldn't it work. I've never had or seen a Circular C-band lnb, but if it bolts up like a linear, in my mind it should work. But, what do I know. I've about talked myself into getting a "Dual C-band / Dual ku-band Linear Feedhorn" like or simular to the "ADL-RP3-2-2B" that's found at the link Mike posted above. The way that feedhorn is made, with the 2 C-band lnb's (as well as the 2 ku-band lnb's) 90 degrees different from each other, whether you call it h/v or l/r, the polarity would still be opposite of each other. But, my goal here is not a polarity issue. My goal is to acheive a prime focus feed with both a Linear and a Circular lnb's. Now Mike give me the impression it won't work, and he's probably right. I got to find out for myself, I'm curious.

Al
 

audiofredmo

New Member
Jun 14, 2005
4
0
Arizona
Dual "C" / "Ku"

The one thing you might be over looking is what polarity are you willing to give up in this test. Usually a dual feed like that does NOT have a polarizer.

Your original question was would a circular LNB work on a linier feed? I would be willing to bet not as the square wave-guide is meant for H/V signals. But one thing you may have overlooked is that if you tried this configuration; let's say on one of the Ku outputs, you would now longer have access to that polarity for your normal Ku or C/Ku receiver!

And if it did work, what would be the benefit? Improved signal strength, probably. But why give up your ability to surf the sky when you could be watching DBS on another monitor, with a separate DBS dish?

Or possibly the ability to have two LNBF's feeding two DBS receivers independently? That is what multiswitches are for!

If I had that kind of investment into a system, I would use power injectors, H/F splitters, maybe in a real high end system use a router to switch the four incoming signals to several receivers of all makes and types and well as a spectrum analyzer for perfect signal alignment. It would be like having your own in-home cable system. Wouldn't that be cool! Or maybe just go all the way and install a Simalsat dish loaded with all of the LNB's you could fit into it.

I have my BUD for pay TV services, but mostly for surfing the sky. Digital has brought some new challenges to the table, but for a couple of hundred dollars here and there, FTA and the ability to receive non-encrypted digital channels are just fascinating to me.
 

AntAltMike

SatelliteGuys Pro
Aug 28, 2005
3,444
0
ADL has (edit: make that: "had") a polarizer-driven, single C/single Ku feedhorn that can be either H/L or L/R on C-band, but I don't remember if the Ku was also circularly capable. At the time I did this installation, I think all the Ku was linear anyway and I just needed to get a sports bar something to pick up circularly polarized soccer signals from some NSS C-band satellites over the Atlantic Ocean.

From: Ku Satellite's website:

"The ADL DP3-International, for the reception of international & domestic satellites (circular & linear C-Band), as well as linear Ku band.

Note: The DP3-I feedhorn is replaced by the Chaparral Corotor II+ International and it is not recommended for dishes less than 10ft in diameter."


You get C-band linear polarity by setting the polarizer probe at zero or 90 degrees, and you get right and left circular by setting it at 45 and 135 degrees.
 
Last edited by a moderator:
Status
Please reply by conversation.

Users who are viewing this thread

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

Latest posts

Top