The patch antenna POTY

Latest News and Discussion about the use of the DATV transponder on Es'hail-2
AdrianH
Posts: 20
Joined: Thu Jul 18, 2019 2:46 pm

The patch antenna POTY

Post by AdrianH » Wed Aug 07, 2019 2:08 pm

Does anyone know if using 1.5mm thick brass sheet makes a difference to using 1mm think sheet on the POTY, just that I have some left over from a job. I guess that for the reflector it makes little difference but not sure on the front element and the spacing..

Or.

Is there a supplier in the UK of the plates to put one together? I did not see any in the shop.

Many thanks

Adrian
G8UGD

g0mjw
Posts: 887
Joined: Sat Sep 20, 2014 9:15 am

Re: The patch antenna POTY

Post by g0mjw » Wed Aug 07, 2019 7:42 pm

No difference - apart from it's harder to bend.

Mike

AdrianH
Posts: 20
Joined: Thu Jul 18, 2019 2:46 pm

Re: The patch antenna POTY

Post by AdrianH » Wed Aug 07, 2019 8:16 pm

Excellent the man him self, thank you for the response.

I am guessing here that the 5mm from the end of the tube is critical and that the 3mm spacing between the plates is critical, is that correct?

It has been a long time since I did any modelling in antenna software, I tried to remember mmana-gal but gave up rather quickly today. Thank you for your design.

Adrian
G8UGD

g0mjw
Posts: 887
Joined: Sat Sep 20, 2014 9:15 am

Re: The patch antenna POTY

Post by g0mjw » Wed Aug 07, 2019 9:13 pm

Only the 3mm spacing is critical.

AdrianH
Posts: 20
Joined: Thu Jul 18, 2019 2:46 pm

Re: The patch antenna POTY

Post by AdrianH » Wed Aug 07, 2019 9:22 pm

Thank you.
G8UGD

AdrianH
Posts: 20
Joined: Thu Jul 18, 2019 2:46 pm

Re: The patch antenna POTY

Post by AdrianH » Thu Aug 08, 2019 5:44 pm

OK built the patch antenna, but before I go much further and do the cone, I believe I have some black nylon6 some where, will have to check it does not get hot in the microwave first.

thought I would post some pics of the results, I have used one of the 3000MHz RF bridges to find the two resonances testing VSWR first with just a co-axial tail on and then after with the Patch connected.

So this is the test set up before:
Patch2.jpg
Patch2.jpg (35.15 KiB) Viewed 499 times
This is the result the top line is the open co-ax and bottom is connected to the patch:
Patch1.jpg
Patch1.jpg (38.5 KiB) Viewed 499 times
And this the patch.
Patch3.jpg
Patch3.jpg (27.96 KiB) Viewed 499 times
Now the questions the traces are 10 dB per div vertical, and 50 MHz per div horizontal.

The two resonances are 2317 MHz and 2514 MHz which seem a lot wider then the patch instructions so. The question is is this two wide. The dims are within 0.04mm on my calipers which is about as good as I can get.

Is the metal too thick? Do I need to start bending? Or will this be OK?

Cheers

Adrian
G8UGD

g0mjw
Posts: 887
Joined: Sat Sep 20, 2014 9:15 am

Re: The patch antenna POTY

Post by g0mjw » Thu Aug 08, 2019 6:46 pm

Looks OK - perhaps the thicker metal explains the extra spacing. 0.04mm is pretty good.

Mike

AdrianH
Posts: 20
Joined: Thu Jul 18, 2019 2:46 pm

Re: The patch antenna POTY

Post by AdrianH » Thu Aug 08, 2019 7:08 pm

OK thank you for the response, the patch filled a day in the garage so no great loss if it was not suitable, I would just go buy one from somewhere, seen some for sale in France!

I will do the cone next and see if it brings it slight down in freq, I was surprised that it was basically above and below 2400.

Can you please do me a favour as I do not understand, can you show the resonant lengths along the patch for above and below or point me to an explanation, all the ones I have seen so far have been slightly off square square patch antennas.

I am still a long way from TX as I would need a decent amplifier for 2.4 GHz.

Adrian

The main concern was that at 2.4GHz I would appear to have a bad antenna?
G8UGD

G8PEF
Posts: 126
Joined: Mon Oct 30, 2017 6:42 pm

Re: The patch antenna POTY

Post by G8PEF » Thu Aug 08, 2019 7:43 pm

Blimey, Mr H - G8UGD; there's a blast from the past... I reckon I last saw you in 1978, probably somewhere in North Oldham! Are you still around the Oldham/Manchester/Bolton area?

I'm following this post with interest, as I'm about to have a crack at a POTY myself, and I'm interested to see where you go with the dielectric lens... I have a couple here which aren't the same as the 'regular' ones seen on most of the feeds, and I'm keen to see how they perform.

73 de John, G8PEF

g0mjw
Posts: 887
Joined: Sat Sep 20, 2014 9:15 am

Re: The patch antenna POTY

Post by g0mjw » Thu Aug 08, 2019 7:45 pm

I would test it and see. The cone design by Willi works well - https://rfantennas.files.wordpress.com/ ... .jpg?w=768 see https://rfantennas.wordpress.com/2019/0 ... vergleich/ Google translate make a good job of translation to English.

PS - I was in Bolton this week.

Mike

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