The patch antenna POTY

Latest News and Discussion about the use of the DATV transponder on Es'hail-2
AdrianH
Posts: 29
Joined: Thu Jul 18, 2019 2:46 pm

Re: The patch antenna POTY

Post by AdrianH » Thu Aug 08, 2019 8:18 pm

First response to Mike then I will waffle. I just tried the black nylon in the microwave, opposite site of the turntable to a cup of water and 3 mins at 900 Watts and the nylon was warm to getting hot, so in my mind not suitable, I will have to get some natural coloured Nylon 6 from the bay of E. Or buy a cheap Rocket LNB from Germany and rob the cone, or perhaps both! I will read the links, thanks again.

Now for the waffle, I was in Bolton some 19-20 years ago now in the Blackburn area. I wonder if I passed details of some surplus microwave kit on to you Mike many years ago. I worked for Pye Telecoms when it existed, then for a Motorola style company called Pennine Comms, then one that got taken over several times, (Tactico, National Telecomms and finally Alcatel) before moving to an independent for 27 years in Leyland, Lancashire. Worked along side companies like Granger years ago, one amongst several other companies. I found being a radio ham and doing radio as a job and being asked to do repairs or "can you get, do you have" to be soul destroying so I dropped the hobby and every thing with it completely.

But I have retired and I am looking back to the original interest for myself, location is in a valley, so looking to the sky for assistance.

Hello John, yes I remember you from many years ago, last time I saw you was in a caravan if I have the correct person? Not had contact with any of the old crowd literally since that period. Robin, Melvin? Peter. Alan and a guy that broke electronics down to components and scrap metal. In fact I would probably have done most things to stay away as said I dropped the hobby completely. The last real time i can remember was playing 70 cms am ATV.

Adrian

G8KOE
Posts: 16
Joined: Fri Aug 09, 2019 8:14 am

Re: The patch antenna POTY

Post by G8KOE » Fri Aug 09, 2019 8:19 am

Help Needed.
Purchased the POTY KIT and assembled as instructions.
Double check the 3mm spacing between plates all looking good.
My dish is a prime focus 1.8M F/D Ratio 0.38 Focus Length 68.4cm
I am using a 2 turn Helix dual feed with my Octagon LNB which is working well.
The dual feed POTY patch antenna doesn’t come close the 2 turn Helix on TX and on RX works better with the lens attached which instruction say isn’t necessary on a prime focus dish.

Hope someone who can help.

Martin

g0mjw
Posts: 958
Joined: Sat Sep 20, 2014 9:15 am

Re: The patch antenna POTY

Post by g0mjw » Fri Aug 09, 2019 7:03 pm

The feed is not designed for a 0.38 F/D antenna and will be less efficient - but not that bad if accurately reproduced.. It should work on RX but you have to be at the correct focus and it is very critical with deep dishes. Adding the lens should not make it better, unless it compensates for the focal length.

Willi, HB9PZK did an analysis:
Capture.JPG
Capture.JPG (130.06 KiB) Viewed 931 times
10 GHz without a lens:
Capture1.JPG
Capture1.JPG (128.55 KiB) Viewed 931 times
Mike

G8KOE
Posts: 16
Joined: Fri Aug 09, 2019 8:14 am

Re: The patch antenna POTY

Post by G8KOE » Sat Aug 10, 2019 5:40 am

Mike thank you for the information.
I had assumed that something was wrong with so many getting good results.
There is so much to learn which make the hobby interesting.

73’s
Martin

g0mjw
Posts: 958
Joined: Sat Sep 20, 2014 9:15 am

Re: The patch antenna POTY

Post by g0mjw » Sat Aug 10, 2019 7:50 am

Just a thought. Unlikely but the patch has to be assembled correctly to get the right polarisation sense - check you have not accidentally built it for the wrong sense. Also what does your VSWR meter well you?

Mike

G8KOE
Posts: 16
Joined: Fri Aug 09, 2019 8:14 am

Re: The patch antenna POTY

Post by G8KOE » Sat Aug 10, 2019 11:28 am

Hi Mike I have assembled incorrectly.
I suffer with dyslexia and couldn't see anything wrong.
Now having compared with other pictures and can see the problem.
I will correct the construction and try again.
Thanks for your help.

73's
Martin

g0mjw
Posts: 958
Joined: Sat Sep 20, 2014 9:15 am

Re: The patch antenna POTY

Post by g0mjw » Sat Aug 10, 2019 11:34 am

Hi Martin,

What did you do wrong? This is interesting as if you had it configured for the wrong polarisation - i.e patch upside down and it matched but worked really badly, that is really good to know as it would imply the polarisation is circular, just the wrong sense.

Mike

G8KOE
Posts: 16
Joined: Fri Aug 09, 2019 8:14 am

Re: The patch antenna POTY

Post by G8KOE » Sat Aug 10, 2019 11:59 am

Hi Mike,
The driven plate is upside down.

73's
Martin

AdrianH
Posts: 29
Joined: Thu Jul 18, 2019 2:46 pm

Re: The patch antenna POTY

Post by AdrianH » Mon Aug 12, 2019 2:54 pm

OK PTFE rod arrived today and I found it a very awkward job to do indeed, PTFE does not hold well in metal lathe jaws, so I think I would recommend buying a rocket LNB and butchering that for the lens.

Nevertheless.
Patch4.jpg
Patch4.jpg (13.49 KiB) Viewed 530 times
and
Patch5.jpg
Patch5.jpg (23.97 KiB) Viewed 530 times
So next to do is a simple adaptor for 40mm and give it a try. I think the 105mm disk may fowl the support arm in which case a rethink on the support, but I want to see what difference it makes to RX comparing the beacon.

G8KOE
Posts: 16
Joined: Fri Aug 09, 2019 8:14 am

Re: The patch antenna POTY

Post by G8KOE » Mon Aug 12, 2019 3:36 pm

Now testing a working Dual Patch feed.
Very critical on positioning for best results.
Now no longer need the dielectric lens on my prime focus dish.
Thanks to all that helped me.

73's
Martin
G8KOE

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