Extension Petals

[RimaNTSS]

This is interesting! I would say, theoretically it is possible to extend offset dish, change LNB's direction and feedhorn and get some increase of signal. But practically this is not achievable, no way. Useless exercise. Much easier is to use bigger antenna.

 

[Waveguide]

I have never considered adding reflector area in a few places as a solution to
increase signal quality. To get a good match to the feedhorn properties is a
lottery with small chances to win. There are many ways to ruin things and
only one way to get good results.

I have planned to do tests in a completely different area, reducing the influence
of the metal structures supporting the LNB. The three metal rods to the focal
point will cause diffraction and some signal losses. When the weather permits
I will compare carbon fibre tubes to the metals tubes used now. Carbon fibre
is a fairly good absorbant of microwaves and the influence of the coax to the
LNB can be reduced running it inside one of the carbon fibre tubes. First I must get
signal strength measurements working, the changes will be small but a quick
test showed a change of 0,2-0,3 dB when adding a fourth rod to the dish.
The daily variation is just as big so it needs some work to separate that from
the influence of the three rods.
Adding absorbant to the metal LNB holder is another test that my be done.
(I've got a well-filled scrapbox of absorbants. Hard to find otherwise.)

 

[RimaNTSS]

Good luck with that! What you are saying now seems more like very scientific job. And that is not easy to exclude weather influence. And also measurements of signals very precisely (precision 0,2 dB ) is not easy task.

 

[Waveguide]

Just making a change once and try to figure out what happened is difficult.
Repeatedly adding and removing something and collecting data all the time is
much easier. A fancy word for this is correlation and in excel this is easy.
That's why my signal measurements will be done by excel so the data ends
up where it is needed.
The signal measurement topic is here:
http://www.satellites.co.uk/forums/linux-receivers-general.698/

 

[RimaNTSS]

I hope I will not open you a secret: Even if you change nothing, you will probably never get exactly the same data measurements!
Are you gona measure all frequencies in left and right polarization?
Anyway, looking forward to see your results. Especially interested in process and way of thinking.

 

[DishDick]

Actually, the focal point remains the same if you follow the parabolic curve. On a PF dish position of the LNB is unchanged.

Thats what I said.

 

[pride21]

hi DishDick the petals were 8 inches from the dish,the dish was a 1.4 mtre offset plus 16 inches then the increased size is roughly 1.8 mtre though it did not work as a 1.8 mtre dish but it gave me more gain than I had hope the helps.cheers

 

[DishDick]

hi DishDick the petals were 8 inches from the dish,the dish was a 1.4 mtre offset plus 16 inches then the increased size is roughly 1.8 mtre though it did not work as a 1.8 mtre dish but it gave me more gain than I had hope the helps.cheers

Thanks