A Polariser Question and Advice

[ArloG]

Getting to the point. Is there a polariser design that will allow both linear and circular reception for a c band feed?
Accepted that a normally used linear feed is used and signal strength for linear transponders will be attenuated.

I've moved to a twin Norsat lnb with high quality orthomode feed. Previously a Titanium Satellite C2W wideband lnbf was used.
For 2 or 3 circular polarised satellites I was able to get adequate dB to attain a lock.
Of course when inserting the slab in the throat. Circular transponders came in strong. And linear tp's signal diminished.
That was with the C2W.

With the current ortho setup. My E2 receiver, an osmio4k, and after much fine tuning. Satellites that delivered mid 12 to a high of 15 dB now blast in.
Some floor the signal meter at 100& and up to 18 or so dB. So. I have linear signal to spare. Loss of lock for DVB is as low as 5 dB. Pixelization for DVB-S2 signals starts showing for some channels around 10 dB.
But is seems 100% "blind" to any circular tp's. And as of yet I have not tried a slab in the throat. Unlike the Titanuim and others. There are no grooved slots to slip one into. And no visible probes in the throat of the ortho. But that, I could 'get'.

Since I have signal to spare for linear tp's. Is there a design that anyone is aware of for a polariser that would allow a margin of linear signals to be used along with proper depolarising of circular transponders?

 

[moonbase]

AV-COMM polariser barrel

 

[Satfaca]

Since you're from the US, you might get a chance to find some rare toy like ADL's CPOR motorised feedhorn. There were several versions depending on f/D (all had fixed scalar rings), CPOR-400 even had the Ku part (wouldn't mind having one myself !!!).
After installation I could determine a gain of 3dB-4dB (circular C-band) compared to Chaparral's Corotor.
AV-COMMs barrel completely emulates ADL's design.

 

[Satfaca]

And don't forget to check out John's thread.

 

[John]

And don't forget to check out John's thread.

Thanks for the link - that takes me back in time a bit. .
It served me very well in it's day and also did a couple of mods on the revolving OMT motorised lump to improve it a bit. Sadly when 5G started up in the lower part of Cband here in the UK, around 3.6GHz area and then increased up the band to 3.79GHz area it really ruined serious Cband DX'ing due to there being very strong 5G cells popping up very close everywhere. An expensive journey then started to find suitable 5G external filters and 5G lnb's - in the last few months iv'e scrapped my motorised Cband setup that had many motorised parts to tweek the last bit of performance out of it and i now run two of the new Titanium 5G lnbf's as part of an lnb changer unit on my 2.2mtr PF. One Tit 5G lnbf is set up for linear ops and the other is inserted into an AV-COM circ poloriser for just L & R circular signals - i have to say that the new improved Titanium 5G lnbf's work very well for the price fighting off the 5G interference problem.

 

[ArloG]

The orthomode feed is a Harvard Scientific dual c band feed. I would say very much like a Chaparral ortho but much better.
I was fortunate enough to have a friend who bought a previously owned storage building that was rented by the local catv company.
It has a bunch of abandoned equipment. Pressurized feeds, lna's and downconverters of all types. I picked my ortho because it looked the nicest of the lot. And the Norsat lnbf's were plenty along with the lna's and stuff. The catv/isp has gone to fiber and retired and sold the old dishes.
I had the ortho bead blasted on the outside and powder coated by another friend. The internal waveguide appears silver plated. It's nice!
I have the best signal strength ever. By several dB. An elusive satellite I could never even snag a signal on comes in around 10.3 dB. A DVB tp locks and has a solid picture. A DVB-S2 tp. just pixelates. The rest just blaze in.

But it's a heavy assembly. My dish has a sturdy buttonhook feed. But I added perimeter clips on the dish and support wires through holes in the Chaparral scalar. I just don't believe a depoalariser tube(I'm a Yank and so tempted to spell it the right way. "DepolariZer". lol!) would be my goal.
Two in fact, since I have two lnbf's. I have polarotor feeds a-mundo. C band, C & ku band. I personally feel like I have pro stuff now.

Anyhow. I was fishing for any knowledge and info from anyone who has played around with "slab" (ok I'll say it) depolarizers.
I cannot imagine they work like a snap-action toggle switch. Either you're getting straight H & V. Or stick it in and it's R&L.
I know that's how they are supposed to work and did on the Titanuim lnbf. I gained a lot of signal on circular polari...."z"....ation.
And lost most of signal on linear polarity.

What I guess I'm looking for is suggestions and models of slab dielectric versions that perform...ummm..."half-fast".
I can afford to lose several dB strength on linear sats and still get a solid picture while (okay, again, respecting those who walked with the dinosaurs)
Whilst (better?....is it whilst like William or whilst like Wyle E. Coyote?) gaining a lot of circular tp signal.
Everyone over there must have had a fit when The Beatles played While My Guitar Gently Weeps. Can't imagine it having Whilst in the title....Or in the verse and lyrics. Smack me please. At least I didn't invent Lucas Electrics. The old Ford starts every single time if it has gas and (oops...."petrol") and battery (or is it "bat-tree").

It's only a temporary thing. To scan the rest of the arc and log satellite positions into my dish mover. And interpolate how many encoder counts there between 2 degree separations throughout the polar mount/linear actuator geometry.

C'mon. It's all in fun and a fun hobby to boot. Or is that "trunk"? Hah.