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Goof Proof Patch?

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Following cam man's instructions and not unconsiderable help from Terry I have constructed my first patch.

I cut out the shapes no problem but finding a connector was another matter the one used in cam mans plans is, I belive, unobtainable in single quantities so I opted for a 'Solder SMA stub panel jack captive' item 295 6315 from the RS componants list UK and a plug - plug connector. Spaced the plate to 5mm using pieces of upvc

I AM going to buy a good system ,honest!, but we have been playing with cheapo Hong Kong sets we have a 1.2 and a 100mw 2.4 gh.

Did it work?

My Grandson and I braved the bitter winds, here in the UK, on Sunday and attempted a test, we had planned to go over the park but the cold left us indoors fortunatly we live next to a school so after contacting the caretaker he let us 'play' on the field.

So we are in the field the grandson walks off with the camera he gets 160 yards

(not very far but it is a small school) and there is no decernable difference so I need more room and better weather.

However I have now reread cam man's intructions and some related alternative threads and I wonder if the SMA connector I used has "cocked it up" I now read the centre pin diameter can make all the difference this one is 1.3 mm I left the insulation on having trimmed it back to 5mm, after reading some advice that it should be left on, but that is not so in cam man's design oh well back to the tin snips

But I think I will find a bit more space before I run it over with my car :o

Regards Jeff

Edited by UPUP

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Following cam man's instructions and not unconsiderable help from Terry I have constructed my first patch.

No problem ;)

Do you have any pictures of the finish artical ?

However I have now reread cam man's intructions and some related alternative threads and I wonder if the SMA connector I used has "cocked it up" I now read the centre pin diameter can make all the difference this one is 1.3 mm I left the insulation on having trimmed it back to 5mm, after reading some advice that it should be left on, but that is not so in cam man's design oh well back to the tin snips

Dont panic too much about the pin diameter, you should still see a good improvement.

Terry

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Hi Terry

I will take some photos to post, very ordinary even though in a past life I was a pipefitter using lead,would you belive. This is the first time I have soldered Galvanise so a bit messy on the back plate.( bit over confident I should have had a practice on some scrap ;) ) front plate OK

We were getting ramdom flashes in almost the form of horizontal lines but never lost picture.

Regards Jeff

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Hi, i am trying to build a GP Patch Antenna using the instructions from the main site. So far i cut out the metal pieces and drilled the holes. I am now about to start soldering in the SMA Connector, but i ran into some questions...

First, do i solder the center post of the SMA Connector to the ground plate? Or is it intended to have it NOT touching or being electrically connected to the groundplate?

Second, how am i supposed to trim the SMA Connector legs to be flush with the front side of the ground plate? File them down? What kind of tool would you propose to do the trimming?

Thx in advance,

Jens

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First, do i solder the center post of the SMA Connector to the ground plate? Or is it intended to have it NOT touching or being electrically connected to the groundplate?

It must not touch it. The 90 mil hole (shown on the plans) ensures that the SMA center post cannot touch the ground plane reflector.

how am i supposed to trim the SMA Connector legs to be flush with the front side of the ground plate? File them down?

Metal file, electric Dremel tool, grinding wheel, etc. Whatever tool/method is easiest for you. The metal is soft, so it shouldn't be difficult to do.

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Thx for the quick answer! Since the drill slipped some way during drilling, the center post is kind of almost touching the ground plate. I was thinking about using a bit of cable isolation to prevent contact. Would that be ok?

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Do not use the tubing to isolate it; Move the hole over. The SMA center post should be at the center of the hole. If necessary, start over with new sheet metal.

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I think that brings up an interesting subject. What kind of performance changes can one expect for slight dimensional errors? I tried cutting the metal plates in a machine shop to the dimensions listed and then used a digital caliper to check and trim each surface. I'm afraid I was a little rushed on the holes for the SMA connector and it is off to one side - maybe about 1/3 of the way across the hole instead of half way.

Similarly, I've got some balsa wood that measures about .195" and another piece that measures .205". Should I take time and try to sand the .205" down to exactly .200"? I'm thinking the glue might push it up anyway.

I'm just wondering if 1/16" on one of the plates (for example) or this much on that part will vary the tuning that much.

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Any variations will change the antenna. Without testing it is hard to say what the performance impact will be. Could make it better or worse. I would suspect the latter.

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Adjustments on antennas for these frequencies by hams are usually made with a file. Every little bit of dimension either way can hurt or help...... Depends upon how good your frequency and RF instruments are.

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Hi!

I´m constructing the GPP antenna, and want to know if I can use this SMA right angle PCB connector:

http://www.rfsupplier.com/product_info.php...products_id=176

Technical specifications are identical to the straight one, mainly in relation to insertion loss, with which I´m concerned.

Using the right angle connector I intend to have a more compact and robust construction.

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The problem with using a Right Angle SMA is that it will probably require a feedline/coax to connect your 2.4Ghz Rx. Part of the GP Patch success is eliminating the feedline.

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No problem ;)

Do you have any pictures of the finish artical ?

Dont panic too much about the pin diameter, you should still see a good improvement.

Terry

I would like to build GPP Antenna for 1.541450 ghz using single sided copper clad board and a chassis mount N cnnector.

The board thickness is about 1.6 mm and with an approx 11 mm hole, the N connector is almost flush with the board, may be 0.5 mm or less.

The N connector post is bigger as is the connector it self, when extending the post height what diameter wire could I use?

Would this patch antenna work ok?

Thanks in advance.

Andrew.

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Copper clad cannot be used. The design is based on an air dielectric and the PCB's laminate will be an issue.

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Copper clad cannot be used. The design is based on an air dielectric and the PCB's laminate will be an issue.

It was going to be used with the copper side up, I wouldn't of thought it would make any difference as it is being used as a ground plane. Air will be used as the dielectric as in your design.

Thanks

Andrew.

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Sounds fine if you limit its use to the reflector (ground plane).

Would everything else be ok, that I mentioned in the original message?

Does the scaling work out as a a percentage?

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Scale per the notes in the project page. Regarding the N connector, post a photo that shows the issue and someone might be able to help out.

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Hello all, this is my first post on these forums. I have been reading about the GP patch for ages and have finally decided to build one.

One question that I've been wanting to ask for ages is; are the 4 small legs integral to the performance or could I get away with using something like this:

http://cgi.ebay.com/50-PCS-SMA-male-chassi...%3A1%7C294%3A30

Cheers,

Lovegroove

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The chassis SMA should be OK. I recommend that you solder it in place instead of using four mounting screws.

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I was just using my GP patch yesterday and managed over 200m behind the patch on the ground. How far should I be able to get behind it? I built it for 1.2GHz and am using a 500mW tx

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It's anyone's guess. You'll need to do more testing to find the backside's range.

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Hi Thomas

I tough the GP patch antenna is circular but I read this in the GP construction steps

" The arrow shown on the template is the orientation for use with transmitters with vertical polarization (e.g., vertical Tx whips). If yours is horizontally polarized then rotate the patch 90º "

I`m puzzle, does the GP is linear or circular polarization ?

Thank

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Vertical polarization. Circular polarization is used for satellite communications (Hams). Don't remember for sure (lost too many brain cells due to ageing), but I don't think there is such a thing as linear polarization that pertains to RF waves.

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I don't think there is such a thing as linear polarization that pertains to RF waves.

AFAIK, vertical polarization = linear polarization, with the antenna being oriented vertically ;)

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