Anyone tried to make BIG dish at home?

[mouse3]

For Dx-ing each fraction of dB counts.Ferrite-magnetic polarizer add more noise,are not good for DX-ing.Mechanical skew are the best,i want to make one like in the picture below,but for primefocus dish.

 

[RimaNTSS]

I am also looking for Rotary Actuator. Who has an idea where to get one like on picture or similar?

 

[JanH]

True. For end of all pipes from all dishes (-: must be something like that.

I mean fine adjustment before pipes connected together. I think feritte inside polarizer just shape magnetic field becouse it could not do something on microwave directly. Something like static magnet. For small adjustment may be enaught magnetic field from outside of pipe only without ferrite. It could be easy experiment to try - magnet for example from loudspeaker and pull on to pipe. I would like to check it bat for me experiments on roof are not so popular in this time.

 

[mouse3]

I found samthing,but nobody here talk about experiments or performance...
Sounds intresting,to add more surface to LNC probes...using one pcc 12 GHz antenna inside the feedhorn.
Increasing the probes surface,increasing the gain...wright or wrong ?
This antenna are from 8 to 20mm long perfect for SHF range.

Magnetic field and microwave,this combination need more experiments in the future...the strongest magnets are use inside the CD-rom,each desktop have this items inside....two cut in half of the circle.

 

[Trust]

I am also looking for Rotary Actuator. Who has an idea where to get one like on picture or similar?

A dutch member (wimpie) of Fibo-owners builds them
There is also german shop selling such thing RT-467 for € 850.-
The pics showing my own projects , instead of the lnb , i skewed the 150 cm PF dish

 

[RimaNTSS]

Trust1! Interesting project! Skewing PF dish is basically same as you skew LNB, only difference is that more weight added to construction. How do you point your dish to satellites? Is that polar-mounted?

 

[Trust]

Rimantss , I don't have that setup anymore but it was a 2 axis EGIS rotor , capable for up to 300 cm dishes . It was easier to find and steer that heavy stuff than that fine mechanic for rotating the lnb .
Later I build me a 30 cm off-set "Crazy Dish" (google) and a Echostar 120 cm off-set project is on the way .

Both have a motor rotator on the elevation axle .

 

[mouse3]

Rimantss , I don't have that setup anymore but it was a 2 axis EGIS rotor , capable for up to 300 cm dishes . It was easier to find and steer that heavy stuff than that fine mechanic for rotating the lnb .
Later I build me a 30 cm off-set "Crazy Dish" (google) and a Echostar 120 cm off-set project is on the way .

Both have a motor rotator on the elevation axle .

One more picture about this subject...

 

[RimaNTSS]

Mouse3! Could you please post more pictures of your antenna taken from different positions? How do you control all those actuators?

 

[Trust]

Nice job , as well the counterweight and the lnb-selector .
My experience is , with a counterweight , less motor noise .
On my first set-up , i also have a lnb selector , Ku/ Dbs lnb .
Because my analog Anderson receiver didn't receive the upper part of the KU band , therefore i used the DBS lnb .

 

[mouse3]

Mouse3! Could you please post more pictures of your antenna taken from different positions? How do you control all those actuators?

It s not my antenna,i have this picture on my database...

 

[JanH]

I found samthing,but nobody here talk about experiments or performance...
Sounds intresting,to add more surface to LNC probes...using one pcc 12 GHz antenna inside the feedhorn.
Increasing the probes surface,increasing the gain...wright or wrong ?
This antenna are from 8 to 20mm long perfect for SHF range.
QUOTE]

I am not shure if I understud. You mean reflector in focus point pointed to LNB or pipe in midle of dish?

I think it depend on how energy is focused in focal point of the dish. If the energy area is bigger than feedhorn it should be better with reflector. When you collect by subreflector too big area then you collect signal as well as noise from "empty" area.
Probes surface should be same as dish energy focus pattern.
Subreflector gives you some lostes too.

Other point of view - for used dish f/d should be specific feedhorn design which collect maximum energy.
JH

 

[JanH]

Doas anybody know what is best f/d for todays ordinary LNB?
JH

 

[mouse3]

Here ar the picture about,pcb antenna for GHz.I want to install this small pcb antenna inside the feedhorn and attached to the LNC probes,do you understand now ?

 

[JanH]

Yes :-)
Quite new wind in this forum. I am curious about it.

I try to find some ideas on internet. There ar may be usefull links about feeds and dishes:

_http://www.w1ghz.org/antbook/conf/Multiple_reflector_antennas.pdf

_http://www.qsl.net/n1bwt/chap5.pdf


In same time I find something about ofset antenas design. It for me main thema now. I will try to resolve "Universal LNB" feedhorn parameters, for what antennas are suitable ( in fact ).
JH

 

[franksanderdo]

Doas anybody know what is best f/d for todays ordinary LNB?
JH

Hi JanH

usually those ordinary LNB have a f/d of approx. 0.6 to 0.65 depending on the manufacturer

I hope this helps?

Best wishes for the new year ;-)
Frank

 

[JanH]

Thank you Frank,

looks designed for offset dishes (not surprising). Round older parabolic dishes have usually about 0.35 and new universal LNB is not too convenient for it. I would like check my offset dishes for f/d if it is right, but roof is with snow now :-)

Happy New Year!

 

[mouse3]

It s a bit late,sorry,Happy New Year,Guys

 

[JanH]

Here ar the picture about,pcb antenna for GHz.I want to install this small pcb antenna inside the feedhorn and attached to the LNC probes,do you understand now ?

What is f/D parameter of yours big dishes?
I think it is very important for feedhorn design.
JH

 

[JanH]

Somethink may interesting about new feed design.
JH