Dielectric plate ?

[Channel Hopper]

..just as an addon to what I posted above ..
The origional in line polariser was unusual insofaras ..it did not rotate a probe..
In actual fact it had a small motor driving a nylon gear external to the waveguide ..which in turn rotated a circular gear inside the wavegide.
This circular gear was atached to series of linked plates in a line..which ran lengthways down the wavegide.
one end of this series of linked plates being anchored.
The first plate would rotate through 90 degrees dragging the other plates behind ..sequentialy..
The net effect was to form a twist in the wavegide pipe ..and thus rotate the signal through 90 degrees.
Did you ever see one of these before ?
rgds
VS

Yes, it was the original C120 flange mechanical polariser design, usually branded Ferguson, and fitted on the IRTE 1.5m polarmount reflectors. Don't throw it away as it is probably the best design out there, even after 20 years.

 

[doktorofsat]

today I'll start to make a new kind of "amplifier" for circular polarization

I can't get Cu foil 'till now, but i got a 1m long and 4mm thick yellow Cu wire.

I'll start something new and very cool, stay tunned 'cause I'll upload some photos evening

 

[Vipersan]

Yes, it was the original C120 flange mechanical polariser design, usually branded Ferguson, and fitted on the IRTE 1.5m polarmount reflectors. Don't throw it away as it is probably the best design out there, even after 20 years.

Hi CH sadly I no longer have that polariser ..
I suspect it was thrown out some 7 years back ..by my ex wife ..
She had a mania for clearing out ..whilst I was at work ..
The fact that we are divorced ..probably says a lot ;)

btw ..package arrived this morning ..
many thanks
VS

 

[nelson_b]

hi nelson_b i tried your lenth of strips starting 10mm next 11.5mm and so on but i found the signal degraded so i got my original plate in lnb,my mesurements are first 7.5mm next 10mm,11.5mm,11.5mm,10mm and last 7.5mm,it seems the best for me with 12mm outside lnbf,i tried to put it inside but it degrades so much.

hi - pride21 -
it looks as if there will be no single plate that will be good for everyone -- each dish / l.n.b. setup will need its own tailor made plate -- i,v now found that the length of the top strips are not as i thought - making any difference for me -i,v tried a few different lengths now

- the step forward on the second plate i made -- was for me
- i think - down to the strips being made a little thinner 3.5 mm rather than 4 mm ---- the spaces between them was 5 mm on both plates --
the third plate was a copy of plate 2 but using thin brass - intead of alum - foil -- and seems to be the best so far --

i,m not at work today - so have been rescanning c band sats to
give a wider test
all good so far - it pulled in 4023 R Tele Congo on 5 west - just watchable - slight break up - never had that t.p. before to my knowledge

regards nelson.b

 

[doktorofsat]

using thin  brass

What is a thin brass??!!Please tell my 'cause I don't understand!

Ad photo with it

 

[nelson_b]

using thin  brass

What is a thin brass??!!Please tell my 'cause I don't understand!

Ad photo with it

hi --
the screenshot below explains it best --
i did not buy any -
i had some on the shelf in my garage --
cant even remember who gave me it --

regards nelson.b.

View attachment 25474

web address for screenshot page _http://www.whimsie.com/brasssheetmetal.html

 

[doktorofsat]

nelson_b , vipersan, pride 21 check also http://www.satellites.co.uk/satellite/880239-post1.html

You are so lucky nelson I can't get alloy foil 'till now

 

[pride21]

hi doctorofsat i see your photos its like another project i have been working on,see pic

 

[pride21]

hi nelson_b well done on tele congo thats a hard one,your right on different plate on different dishes.

 

[Crisbe]

For those of you in the UK. RS Components sell sheet materials such as nylon, polycarbonate acrylic, polyester, polyurethane, polyethylene etc.etc. I can't tell you what the dielectric qualities of any of them are though as the book does not give that info.

 

[doktorofsat]

Today I made some new tests

I made in 5minutes a very simple plate and I got execelnt results on several weak tp

For example with the plate I presented before It was very hard to get TV2
Denmark 3778 L 1900 7/8! from 49E(which has a much lower power then other tp) but with this plate works excelent on my 1,5m pfa I noticed a better reception of 64E also.

Please made some tests with the plate, I upload the measures of da 2 Al foil you need , 5 minutes of work and you have a cool plate.I wait for replies

 

[nelson_b]

Today I made some new tests

I made in 5minutes a very simple plate and I got execelnt results on several weak tp

For example with the plate I presented before It was very hard to get TV2
Denmark 3778 L 1900 7/8! from 49E(which has a much lower power then other tp) but with this plate works excelent on my 1,5m pfa I noticed a better reception of 64E also.

Please made some tests with the plate, I upload the measures of da 2 Al foil you need , 5 minutes of work and you have a cool plate.I wait for replies

hi - doktorofsat -
i made one of these plates and tried it yesterday --
the results were not so good for me on my setup -- (most signals down in strength and quality )
the best all round results so far have been with the plate -pictured in post 65 -
-and the only problem i had with it explained in post 79 -- other than that its given me increased strength and quality all round and a few extra transponders
-- i will be too busy at work for the next few weeks - to do much experimenting -- but i will watch with interest this thread and the " bandits teeth" one .

regards nelson.b.

 

[pride21]

hi doctorofsat i made a plate from your latest design i am afraid it did not well for me i lost channels for example on 5w i lost ktn,afnex,rgt1,and canal2 int the plate i made seems the best,i altered the dimensions from the original plate but works very good now.

 

[pride21]

hi all well after making about 15 plates with different variations this is the final plate it has good gain on most channels.

 

[macssam]

as soon as I insert the circular plate
all signals are gone
the diselectric insert came with my Ku/C-Band lnb
I have a 12ft motorized mesh in the caribbeans

any ideas what could be wrong

 

[Vipersan]

as soon as I insert the circular plate
all signals are gone
the diselectric insert came with my Ku/C-Band lnb
I have a 12ft motorized mesh in the caribbeans

any ideas what could be wrong

Hi Macssam ..
I'm assuming you mean a plate used when receiving circular polarised signals ...and not a plate that is actually circular in shape ?

My guess is that you have your dish pointed at satellite which broadcasts using Horizontal and Vertical polarisation..
The effect of inserting a dielectric plate under these circumstances will indeed kill ...or certainly reduce signals to unusable levels ..

H and V polarisation ...plate should be removed ..
Circular Left or Right ..plate should be inserted..

just out of curiosity ..which satellite are you pointing your dish at ??
rgds
VS

 

[macssam]

Hi Macssam ..
I'm assuming you mean a plate used when receiving circular polarised signals ...and not a plate that is actually circular in shape ?

My guess is that you have your dish pointed at satellite which broadcasts using Horizontal and Vertical polarization..
The effect of inserting a dielectric plate under these circumstances will indeed kill ...or certainly reduce signals to unusable levels ..

H and V polarization ...plate should be removed ..
Circular Left or Right ..plate should be inserted..

just out of curiosity ..which satellite are you pointing your dish at ??
rgds
VS

+

I receive Horizontal and Vertical
Ku + C from 60-140 West
but would like to get some circular without loosing
what I have
I have a DM800 Clone and can NOT hookup a Chaparral Corrotor
because there is no outlet to control the servo

 

[Channel Hopper]

+
I have a DM800 Clone and can NOT hookup a Chaparral Corrotor
because there is no outlet to control the servo

You can, but you would need to build a simple square wave generator with variable control. About 20 components and two hours work, unless you go for a flip-flop design using an integrated circuit.

A circular depolariser system will always lose some signal when viewing the linear channels, really the only way is to fully remove it between satellites.

 

[Turok]

Hello!
i have a circular depolarizer form smw,but currencly without a circular signal recpetion on w4 eutelsat i still cannot test it,how much,aproximently should be the gain winning,when i use this depalrizer?
on circular signals,the scew angle of the lnb,is not so important,then on normal kuband,when the circular signals is strongh enough after the satellite change,i think a normal flange kuband lnb,should do the job also,in my test,the normal kuband signal,with a linar/circular lnb,has exactly the same signal strenth,like on the kuband lnb,i dont know is it via versa when i want to use the kuband lnb on a circular signal the same or not?
maybe i lost to much signal we will see!

 

[doktorofsat]

the strongest signal in circular from 36E ARE

11727 L DVB-S/MPEG-2 27500 3/4 BIZ TV ,K+ ....90% WITHOUT PLATE

12174 L DVB-S/MPEG-2 4340 3/4 TVN................90% WITHOUT PLATE

12303 L DVB-S/MPEG-2 27500 3/4 7TV , BRIDGE need plate for my 125cm offset Q=45%

Others are much lower, pay atention!

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