Low Elevation Angle (1 degree -5 degree) Satellite Reception

[Archive-B]

Satellite signals at low elevation angle (1 deg- 5deg.) to a particular location is affected by many atmosphere related things like atmospheric scintillation, faraday rotation etc. which cause fluctuation in signal quality severely at reception end.

While watching few videos on Youtube I notice that few satellite hobbyist complain about signal jumping from unlock level to lock level particularly with low angle satellites to their locations. This fluctuation also affect channels scaning (sometimes scan 4-5 channels and other time more than 200 chanels !!). What I find that they solve this this signal fluctuation problem by increasing their dish antenna size by making signal fluctuation from Unlock-Lock level to Lock-Lock+(surplus) level.

Roman David at dxsatcs.com solve this problem by placing ferrite isolator between waveguide and LNB. Further search on ferrite isolator reveals that it resists one polarization and allow passing of another polarization. By this action possible signal reflection was reduced and signal fluctuation diminish. But the problems with ferritic isolator is that it can be used with only rectangular type LNB (SMW brand, Norsat brand or New Japan Radio brand type) and for receiving both polarization with fluctuation one need 1 orthomode feedhorn, 2 ferrite isolator and 2 such professional branded expensive LNB.

Few Questions:
1. Is here anybody who manages to receive satellites less than 1 degree elevation to his/her location ? Interested to read your story.
2. Are there any other cheap solution to these two expensive solution? If someone successfully implemented please share here.

[It is possible to rotate feedhorn+lnb combo by external motor like mechanical switching between polarization. Still the price of single LNB and Ferrite isolator remain expensive and not practical to commons]

 

[Channel Hopper]

Don't use a ferrite, stick with a mechanical polarising system.

Put the dish on a tower to remove some of the ground effect and to clear nearby obstructions.

 

[Archive-B]

Don't use a ferrite, stick with a mechanical polarising system.

Yes.
Ferrite device = more insertion loss
Mechanical polarisation skewing become more essential as signal travel long path and suffer many atmosphere related problems which may cause polarisation separation angle from 90 deg. to more than 90 deg. or less than 90 deg.

But what I understands from google translated webpage of Roman David is that he used mechanical polarising system yet signal fluctuation continues so he used ferrite isolator with mechanical polarising system (in his case it was Hirschamnn or sth same name) to significantly reduce signal instability.

 

[Captain Jack]

I have no experience with mechanical polarisers but to answer your other question... Here in S.W. England, I received 72.1E at only 0.6 degrees elevation on an 85cm dish. The signal was very much absent most of the time but occasionally, it went into full lock and allowed me to scan and watch channels until it faded away.

Similar results at 70.5E but with a generally overall stronger signal. 68.5E was always watchable but signal quality varied massively from one minute to the next.

 

[s-band]

Don't use a ferrite, stick with a mechanical polarising system.

Put the dish on a tower to remove some of the ground effect and to clear nearby obstructions.

I haven't seen the original Roman David post but I think that the ferrite reference is to an isolator vs. a polariser. The isolator will ensure a good match between the LNB and what follows. SMW often fit them as standard to their wide band kit. Generally the loss is in the region of 0.2-0.3dB for a good device and that is easily recovered by the advantage of a good match (low VSWR) in some cases.

@st2@88e If you wanted to try one there are a few on Ebay wr75 isolator | eBay Note that some circulators are listed as isolators but do not include the load which you'd need to buy separately.

This one is cheap Racal MESL WR75 R120 waveguide circulator isolator + NERA dummy load 10GHz | eBay however, you'll need to modify it to fit the standard WR75 flange.

I'm not sure it will be a magic solution. A tall tower might help more. One problem is that there may be polarisation skew over time due to the extended distance through the Earth's atmosphere. This is most noticeable at dawn & dusk. You might find that by continuously tweaking the skew it will optimise the signal. If the satellite is below the horizon you're subject to unstable propagation effects and unlikely to get continuous reception, if any as per @Captain Jack post.

 

[Channel Hopper]

I haven't seen the original Roman David post but I think that the ferrite reference is to an isolator vs. a polariser. The isolator will ensure a good match between the LNB and what follows. SMW often fit them as standard to their wide band kit. Generally the loss is in the region of 0.2-0.3dB for a good device and that is easily recovered by the advantage of a good match (low VSWR) in some cases.

@st2@88e If you wanted to try one there are a few on Ebay wr75 isolator | eBay Note that some circulators are listed as isolators but do not include the load which you'd need to buy separately.

This one is cheap Racal MESL WR75 R120 waveguide circulator isolator + NERA dummy load 10GHz | eBay however, you'll need to modify it to fit the standard WR75 flange.

I'm not sure it will be a magic solution. A tall tower might help more. One problem is that there may be polarisation skew over time due to the extended distance through the Earth's atmosphere. This is most noticeable at dawn & dusk. You might find that by continuously tweaking the skew it will optimise the signal. If the satellite is below the horizon you're subject to unstable propagation effects and unlikely to get continuous reception, if any as per @Captain Jack post.

I read through the original post (not seen the the text from RD either), and the 'isolator' mentioned does not fit the description.
Isolators that you have provided eBay links to are already single polarity WR75 fitment, their use is - in most cases - to stop reflected signals from affecting other equipment in the waveguide. A one way road for signal.

Some isolators can be 'tuned' to best remove the reflection, whilst I've not used one I would expect this could also be used to better reject signals within the band of interest, (eg low or high Ku band)

I doubt very much an isolator is going to be the first step to improving low elevation reception, best get the major work done first.

 

[s-band]

I doubt very much an isolator is going to be the first step to improving low elevation reception, best get the major work done first.

Agreed

I read through the original post (not seen the the text from RD either), and the 'isolator' mentioned does not fit the description.
Isolators that you have provided eBay links to are already single polarity WR75 fitment, their use is - in most cases - to stop reflected signals from affecting other equipment in the waveguide. A one way road for signal.

From the description it was hard to be sure, I still think it is referring to a waveguide isolator. I agreed that a magnetic ferrite polariser is not desirable. The improved match from using an isolator may improve the X polar rejection, I guess. The match presented to the feed, even by pro LNBs, is often quite poor.

I use an SMW Q-PLL with a Prodelin feed on an offset Prodelin Ka dish (for standard Ku). The complete feed and LNB assembly is rotated using an RC servo. I don't have an isolator in line. That set-up gives me 28-35dB X polar rejection. For OTH reception I think it's more important to have line of sight to the horizon and to be able to control the skew. The picture shows the version I use for 13.5GHz with a modified SMW PLL LNB. Here's a link to @John skew system:

Just Sharing This - Coming soon - - Ex Viasat Ku Motorised Pol/Skew

Winter project Convert an Ex Viasat Ku band motorised Pol/Skew unit. Remove existing Viasat scalar feed, convert to using Channel Master Off-set scalar and adapt the Viasat unit to fit onto the existing CM feed holder, plus - incorporate into the mod the adjusted feed positioning for the 1.2 or...

satellites.co.uk

SMW Q-PLL LNBs are available from Indian scrap dealers on Ebay for around £120 at the moment.

 

[Archive-B]

I have no experience with mechanical polarisers but to answer your other question... Here in S.W. England, I received 72.1E at only 0.6 degrees elevation on an 85cm dish. The signal was very much absent most of the time but occasionally, it went into full lock and allowed me to scan and watch channels until it faded away.

Similar results at 70.5E but with a generally overall stronger signal. 68.5E was always watchable but signal quality varied massively from one minute to the next.

Your description is matching with a youtuber who received 0.8 degree elevation satellite and share same experience as you. So I am generalizing it as follows
1. Elevation (1 degree to 5 degree) - Signal fluctuation. Most noticeable at dawn & dusk [courtesy -@s-band ]
2. Elevation (0.5 degree to 1 degree) - Signal available for moment and not-available for another moment (Signal ON/OFF cyclically). During available period of time it shows symptom of fluctuation.
3. Elevation (0.1 degree to 0.5 degree) - No confirmed report of reception.

So based on your message I can state with certainty that Captain Jack is the Lowest Elevation Angle Satellite Signal Founder of the World.

I haven't seen the original Roman David post but I think that the ferrite reference is to an isolator vs. a polariser. The isolator will ensure a good match between the LNB and what follows. SMW often fit them as standard to their wide band kit. Generally the loss is in the region of 0.2-0.3dB for a good device and that is easily recovered by the advantage of a good match (low VSWR) in some cases.

@st2@88e If you wanted to try one there are a few on Ebay wr75 isolator | eBay Note that some circulators are listed as isolators but do not include the load which you'd need to buy separately.

This one is cheap Racal MESL WR75 R120 waveguide circulator isolator + NERA dummy load 10GHz | eBay however, you'll need to modify it to fit the standard WR75 flange.

I'm not sure it will be a magic solution. A tall tower might help more. One problem is that there may be polarisation skew over time due to the extended distance through the Earth's atmosphere. This is most noticeable at dawn & dusk. You might find that by continuously tweaking the skew it will optimise the signal. If the satellite is below the horizon you're subject to unstable propagation effects and unlikely to get continuous reception, if any as per @Captain Jack post.

Link to Roman David Original Article :-
1.

Experimental waveguide line for circular & rectangular type of wave with ferritic isolator | CZECH AND SLOVAK DX SATELLITE CLUB

Experimental waveguide line for circular & rectangular type of wave with ferritic isolator Návrh experimentálnej vlnovodnej linky pre spracovanie cirkulárnych a ortogonálnych vektorov vlnení v pásme KU s použitím feritového izolátora .

www.dxsatcs.com

Web-archive link (in case removal in future) - Experimental waveguide line for circular & rectangular type of wave with ferritic isolator | CZECH AND SLOVAK DX SATELLITE CLUB
2. NSS 6 at 95.0°E-Indian subcontinent SPOT : Dish TV DTH & spectrum analysis | CZECH AND SLOVAK DX SATELLITE CLUB
Web-archive link - NSS 6 at 95.0°E-Indian subcontinent SPOT : Dish TV DTH & spectrum analysis | CZECH AND SLOVAK DX SATELLITE CLUB

​

I read through the original post (not seen the the text from RD either), and the 'isolator' mentioned does not fit the description.
Isolators that you have provided eBay links to are already single polarity WR75 fitment, their use is - in most cases - to stop reflected signals from affecting other equipment in the waveguide. A one way road for signal.

Some isolators can be 'tuned' to best remove the reflection, whilst I've not used one I would expect this could also be used to better reject signals within the band of interest, (eg low or high Ku band)

I doubt very much an isolator is going to be the first step to improving low elevation reception, best get the major work done first.

You are absolutely correct. I also read in multiple articles what you wrote here. Same is reiterated by Roman David about signal reflection within waveguide system.

 

[MrDish1]

Agreed


From the description it was hard to be sure, I still think it is referring to a waveguide isolator. I agreed that a magnetic ferrite polariser is not desirable. The improved match from using an isolator may improve the X polar rejection, I guess. The match presented to the feed, even by pro LNBs, is often quite poor.

I use an SMW Q-PLL with a Prodelin feed on an offset Prodelin Ka dish (for standard Ku). The complete feed and LNB assembly is rotated using an RC servo. I don't have an isolator in line. That set-up gives me 28-35dB X polar rejection. For OTH reception I think it's more important to have line of sight to the horizon and to be able to control the skew. The picture shows the version I use for 13.5GHz with a modified SMW PLL LNB. Here's a link to @John skew system:

Just Sharing This - Coming soon - - Ex Viasat Ku Motorised Pol/Skew

Winter project Convert an Ex Viasat Ku band motorised Pol/Skew unit. Remove existing Viasat scalar feed, convert to using Channel Master Off-set scalar and adapt the Viasat unit to fit onto the existing CM feed holder, plus - incorporate into the mod the adjusted feed positioning for the 1.2 or...

satellites.co.uk

SMW Q-PLL LNBs are available from Indian scrap dealers on Ebay for around £120 at the moment.

S-band ;

how did you make ore made the lnb rotatable

Mvg

 

[MrDish1]

Read the article off ; dischdriver, at sat4all.com

 

[Captain Jack]

So based on your message I can state with certainty that Captain Jack is the Lowest Elevation Angle Satellite Signal Founder of the World.

Sadly not.

DX Bozoth in Hungary managed to receive a satellite that was below the horizon! The trick was that the satellite was in inclined orbit, which meant that for a part of the day, it rose above the horizon, allowing him to receive it. I think it was 96.5E a few years back, aimed at the Russian market - not the current G-Sat ones.

 

[a33]

Your description is matching with a youtuber who received 0.8 degree elevation satellite and share same experience as you. So I am generalizing it as follows
1. Elevation (1 degree to 5 degree) - Signal fluctuation. Most noticeable at dawn & dusk [courtesy -@s-band ]
2. Elevation (0.5 degree to 1 degree) - Signal available for moment and not-available for another moment (Signal ON/OFF cyclically). During available period of time it shows symptom of fluctuation.
3. Elevation (0.1 degree to 0.5 degree) - No confirmed report of reception.

From what I've read, due to the atmospheric conditions, you should aim a bit lower than the actual calculated elevation angle, for near-horizon reception. And you can even receive signal from BELOW the horizon!
The adjustment for "elevation" near the horizon on a motorized setup would partly be done with your motor hour angle, I guess. So not at all easy.

Greetz,
A33

 

[s-band]

how did you make ore made the lnb rotatable

The the servo on the right of the picture is controlled using one of these Pololu - Maestro USB Servo Controllers

Link to Roman David Original Article :-

Thanks. That shows it is a normal waveguide isolator that provides good matches either side and passes signal ~20dB less in the reverse compared to forward direction. His set-up is for circular polarisation which means there's no need for a skew control (except possibly to tweak for varying frequency if the de-polariser needs it).

 

[Archive-B]

His set-up is for circular polarisation which means there's no need for a skew control (except possibly to tweak for varying frequency if the de-polariser needs it

What was used in following case in Linear Polarisation ?

( Courtesy - NSS 6 at 95.0°E-Indian subcontinent SPOT : Dish TV DTH & spectrum analysis | CZECH AND SLOVAK DX SATELLITE CLUB )

Under heading :- NSS 6 at 95.0°E-packet Dish TV DTH : author's research activities in the field of wave physics

A turning point in my research activities took place six months ago when I understood the direct relationship between the position sensors waves in waveguides and permanent oscillation, which significantly degraded the quality of reception from the orbital position 95° E.
Then I understood and applied this change in the waveguide,permanent oscillation of all transponders in India and the Middle East footprint reduced by 75%, as evidenced by the quality of video records of reception for different transponders from India footprint.Periods with stable detection of the carrier in the Indian spot was significantly prolonged and specifically in the HD transponder at f = 12 647 V I have identified a stretch of 45 minutes without pixelation and downtime .

 

[Channel Hopper]

What was used in following case in Linear Polarisation ?

( Courtesy - NSS 6 at 95.0°E-Indian subcontinent SPOT : Dish TV DTH & spectrum analysis | CZECH AND SLOVAK DX SATELLITE CLUB )

Under heading :- NSS 6 at 95.0°E-packet Dish TV DTH : author's research activities in the field of wave physics

A turning point in my research activities took place six months ago when I understood the direct relationship between the position sensors waves in waveguides and permanent oscillation, which significantly degraded the quality of reception from the orbital position 95° E.
Then I understood and applied this change in the waveguide,permanent oscillation of all transponders in India and the Middle East footprint reduced by 75%, as evidenced by the quality of video records of reception for different transponders from India footprint.Periods with stable detection of the carrier in the Indian spot was significantly prolonged and specifically in the HD transponder at f = 12 647 V I have identified a stretch of 45 minutes without pixelation and downtime .

Since you are based in India then there is little need to question research on finding channels at near horizon level.