C Band Circular LNBF

[armadillo_115]

Is there a better lnbf to receive Circular C besides adding a dielectric insert to a linear lnbf?
It seems like the dielectric slab would induce some signal loss.

Something with V shaped probes rather than straight probes. Or phased probes,but I'm sure that would be too expensive.

(I need to add a side-mount Circ for 40.5W)

 

[primestar31]

You can build a polariser (<< yes, it's spelled right with an "s") tube: http://www.satsig.net/pointing/circular-polarisation-set-up.htm

Or you can import one from Europe.

 

[MN_Vikings]

armadillo_115,

It’s been a year since my last post on Satellite Guys and and thought I’d add to your post and ask a few questions. I have stuggeled with getting my C-Band dish aimed for three years and now have it perfectly aimed and tracking the arc now from 40.5 to 139. My aiming problem was related to the dialectic plate which induced signal loss in some satellite where you could not get a signal and other satelliies like 40.5 where the the dialectic plate is required to even pick up a signal. During this time I thought my problems was related to the wrong declination angle or the wrong elevation setting or picking the wrong sothern satellite. For testing purposes I used a few different LNB's that had and did not have a dialectic plate inserted. So at times when I was picking up satellites with a dialectec plate due to circular signals I could not pick up other satellites due to signal loss. I would then start playing with the declination and elevation settings and made things worse where I could not track the satellite arc then I would give up.

So it is a trade off if you use or don't use a dialectec plate if you only have one C/KU LNBF on your dish. A second option which I'm looking into is to use multiple LNB's if I can find a dedicated straight C-band Circular LNBF that does not use a dialectic plate. I can confirm the dialectic plate reduces signal strength but is needed for some some satellites. Here are the results of my testing from two satellites 40.5 and 83 last night.
40.5W SES 6 C – got 40 to 44 signal strength picture with dialectic plate.
40.5W SES 6 C – got no signal and no picture with no dialectic plate.

83W AMC 9 – got 36 signal strength with no picture with dialectic plate.
83W AMC 9 – got 66 signal strength great picture with no dialectic plate.
So a dialectic plate does reduce signal loss for me on satellite 83 going from a 66 with great reception to a 36 signal strength with no reception. I would like to throw out a few questions to some other more experienced Satellite Guys members.

Are there any Satellite Guys members have a list of what satellites in North America that use circular signals?
Could a satellite broadcast in both linear and circular signals?

There was a user who posted a link to how to make a Circular LNB without a dialectic plate but where could I purchase one from? I'm talking about a C-band circular straight LNB like in one in my photo attachment.

Until I can find a dedicated circular C-band LNB I will try to again to install multiple LNB's and just found a bracket that may help me properly install two LNB's.
http://www.aliexpress.com/item/C-Ba..._1&btsid=b80f92fe-a66f-4fe5-bd66-29e7b1dc188e

 

[lost_mesa]

Just to clarify a few things about satellite signals and frequency reuse. Satellites transmit completely different signals on the same frequencies in each polarization. In order to receive a signal without interference from a signal in the opposite polarity, you must use the proper feed, either linear or circular, depending on the satellite.

If you use a linear feed on a satellite using circular polarization, you will receive both the left and right polarized signals at the same time. If you use a circular feed on a satellite using linear polarization, you will receive both the horizontal and vertical signals at the same time. In either case, the interference from signals of the opposite polarity will badly degrade the reception. Switching polarity on the receiver will have little affect, you will still receive both polarities at the same time.

Sometimes you can get away with the wrong type of feed, if there is little or no signal on the opposite polarity.

C Band satellites using circular polarity:

53 W
47.5 W
40.5 W
34.5 W
27.5 W
24.5 W
22 W

I can only see to 30 W, so I'm trusting that Lyngsat is accurate. Going east from 22 W there are more circular polarized satellites on C Band, check Lyngsat for the details.

On Ku Band the only satellite using circular polarization below 12.2 GHz is Anik F3 at 119 W. I don't know about the situation east of 30 W on Ku Band, never looked into it.

DBS birds between 12.2 and 12.7 GHz are circular.

The dielectric slab does cause some loss on circular signals, but it is much better than nothing! And it's cheap. The type of feed that primestar31 linked to is the way I've seen all high end systems do it. I came across another type of feed for circular signals that looked interesting. Can't find it now, but if I do, I will post a link to it.

 

[lost_mesa]

Just to add a bit. I have two LNBFs mounted on my 10 ft dish, a linear feed at the prime focus and one mounted offset for circular. The second LNBF cost me $24. I didn't modify them, just put them side by side. That's probably costing me a few dB, but I still get about 100 itc channels from 40.5 W. Occasionally I'll move the dielectric slab into the main LNBF if I want a few more dB of signal.



Here is a good discussion about doing it right. http://www.satelliteguys.us/xen/threads/c-band-linear-circular-orthomode-feed-modification.193463/

Not sure how available these ADL feeds are, but looks like they run upwards of almost $400.

Satellites don't broadcast both linear and circular in the same band, but some are circular on C Band and linear on Ku Band.

Hope this helps!

 

[MN_Vikings]

Everyone, I found this post from 2013 and added a few more from lost_messa: http://ftabeta.com/archive/index.php/t-52075.html


Here is a list of satellites and the correct lnb's to use with them:

40.5W NSS-806 - use standard circular lnb - 11250 MHz

45W Intelsat 14 ???????

47.5W - use standard circular lnb - 11250 MHz

50W Intelsat-705 ???????

53W Intelsat-707 - use standard circular lnb - 11250 MHz

61.5W Echo 3 - use standard circular lnb - 11250 MHz

63W Estrela - use linear lnb, either universal or standard linear- 10750 MHz

71.8W Nahuel 1- linear lnb, either universal or standard linear- 10750 MHz

72.7W Nimiq 5 - circular standard lnb - 11250 MHz

77W Echo 4 - circular standard lnb - 11250 MHz

79W Amc 5 - linear lnb, either universal or standard - 10750 MHz

82W Nimiq 2 - circular standard lnb= 11250 MHz

87W Amc 3 - --- linear lnb, either universal or standard - 10750 MHz

91W Galaxy 11- linear lnb, either universal or standard- 10750 MHz

91W Nimiq1&3- circular lnb standard= 11250 MHz

93W Intelsat 6- linear lnb, either universal or standard-10750 MHz

95W Galaxy 3c- linear lnb, either universal or standard - 10750 MHz

97W Intelsat5- linear lnb, either universal or standard - 10750 MHz

101W Amc 4 - linear lnb, either universal or standard- 10750 MHz

103W Amc 1- linear lnb, either universal or standard- 10750 MHz

105W Amc 15- linear lnb, either universal or standard- 10750 MHz

107.3W Anik - linear lnb, either universal or standard- 10750 MHz

110W Echo 8 & 10,X - circular lnb standard - 11250 MHz

111W Anik f2 - linear lnb, either universal or standard - 10750 MHz

116.8W Satmex5 - linear lnb, either universal or standard - 10750 MHz

118.7 Anik- Special Low Frequency circular LNB--standard - 10750 Mhz

119W Echo 7 - circular lnb standard - 11250 MHz

121W Echo 9 - linear lnb, either universal or standard - 10750 MHz

123W Galaxy 10r - linear lnb, either universal or standard - 10750 MHz

127W Galaxy 13 - linear lnb, either universal or standard - 10750 MHz

129W Echo 5 - circular lnb standard - 11250 MHz

148W Echo1 & 2 - circular lnb standard - 11250 MHz

 

[armadillo_115]

MN_Vikings, 40.5 is mostly C band as far as FTA in N America.That's the 1 Sat I really want to pull in.

I haven't looked thru all the list yet.

EDIT: NSS 806 is at 47.5...has both C and KU.
EDIT 2: 50W/Intelsat 1R is linear C and KU
I believe that list is outdated...or I'm misreading Sathint and PortaEDS.

 

[Titanium]

A few years ago over on the satellites.co.uk forums they discussed customized dielectric slabs. They were designing and constructing for improved circular reception and reduced losses over the standard slabs included with most LNBFs. A very interesting read with members etching boards and using different materials.

 

[armadillo_115]

I've pretty much decided to side-mount a C1W-PLL with the dielectric slab when the time comes.

Once I eliminated the the Non-FTA birds...and the ones out of footprint...and the ones with nothing of interest to us ( Sports, feeds, Portuguese, duplicate channels) ...I only care about adding 40.5 C Circular anyway.

But I'm open to suggestions if I over-looked anything.

Maybe an offset dish later for 30W HispaSats and I'll be done.But it isn't a priority unless momma finds out what she is missing.lol

 

[KE4EST]

But it isn't a priority unless momma finds out what she is missing.lo

You know if she finds out, you will be ordered to get a dish on 30W.

 

[lost_mesa]

Here is a list of satellites and the correct lnb's to use with them:

40.5W NSS-806 - use standard circular lnb - 11250 MHz

45W Intelsat 14 ???????

47.5W - use standard circular lnb - 11250 MHz

50W Intelsat-705 ???????

53W Intelsat-707 - use standard circular lnb - 11250 MHz

61.5W Echo 3 - use standard circular lnb - 11250 MHz

63W Estrela - use linear lnb, either universal or standard linear- 10750 MHz

71.8W Nahuel 1- linear lnb, either universal or standard linear- 10750 MHz

72.7W Nimiq 5 - circular standard lnb - 11250 MHz

77W Echo 4 - circular standard lnb - 11250 MHz

79W Amc 5 - linear lnb, either universal or standard - 10750 MHz

There are quite a few errors in this list.

A L.O. of 10750 is a standard Ku LNBF, 11250 is a DBS LNBF. C Band is 5150, but isn't mentioned at all in this list.

With the exception of Anik F3, everything over North America on Ku Band between 10.9 and 12.2 GHz is linear. Dual band satellites that are circular on C Band are linear on Ku Band.

A couple of examples:
40.5W (SES-6) on Ku Band has signals from 10.9 to 11.2 so needs an L.O. of 9750 and is linear, not circular. (I've never seen video on Ku Band on SES-6).

47.5W has no Ku Band coverage over North America.

53W has signals from 11.7 to 12.2 GHz so needs an L.O. of 10600 or 10750 and is linear, not circular. (One channel of video on Ku Band).

These three satellites are circular on C Band, but linear on Ku.
Hope this helps.

 

[clucas]

A few years ago over on the satellites.co.uk forums they discussed customized dielectric slabs. They were designing and constructing for improved circular reception and reduced losses over the standard slabs included with most LNBFs. A very interesting read with members etching boards and using different materials.

Hey Brian. The dielectric slabs in my A1W-PLL's have a black piece of rubbery tape on them. I've been peeling it off. Why is it there? It's not necessary for any reason, is it? (Don't want the signals hitting it and bouncing back. Just kidding about that.)

 

[Titanium]

Amalgamated rubber tape provided to secure the dielectric slab into optimized position (or wrap the f-fitting). Remove it or use it!