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Rob Moll

Will the GP Patch antenna work with this receiver?

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I made my first successful fpv flights recently and now need to get a better video link. I would like to try the GP Patch before upgrading TX or RX. I fear that my RX is a piece of junk but I believe that the GP Patch is a good first step at improving since I can carry it forward into most any RX I may purchase. If, based on the pics, you know that the RX is not worth trying to improve, please tell me so.

My question is - since my existing omni-antenna is not detachable conventially, can I still use the GP Patch with it by unsoldering the antenna lead from what appears to be a di-pole pcb and then soldering the lead directly to the Patch, bypassing an SMA connector? Or should I solder the existing lead to an SMA connector? Or...???

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100_2127_small.jpg

Thanks in advance for any help.

Rob

edit - Images were resized.

Edited by Rob Moll

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... and then soldering the lead directly to the Patch, bypassing an SMA connector? Or should I solder the existing lead to an SMA connector? Or...???

If you have the recommended expensive tool, and experience, I suggest crimping on a SMA to the coax. Otherwise, do your best with the soldering idea. Keep in mind that it is easy to deform the coax's dielectric, which will impair its performance.

Another idea is to solder a chassis mounted SMA to the Rx's sardine can, like has been discussed with the Airwave modules (search the rc-cam forum for details). Then purchase a very short *factory made* SMA coax cable for connecting the Rx to the GP Patch.

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I suggest you size pictures to 640 or 800 in width.

Coax should be keept as short as possible,

Normal wires or open wires for 2.4Ghz signals will degrade your 2.4Ghz links,

even 1 cm is fatal,

if possible do what Mr Cam recomment solder the SMA connector DIRECTLY to the radio cans on each end, you need skils and luck, but the result is worth the effort.

I suggest a Patch antenna to minimise the droupouts and improve range.

The Goofprof is a good way to go,

there exist an updated version with even better data and more range:

www.webx.dk/rc/video-wireless/PATCH4.pdf

this drawing is not in release status yet, but will be in a few days :-)

I suggest you see the range and picture qulity I have:

www.webx.dk/rc/video-wireless/2007-03-20-50mWcomp.wmv

here with only 50mW power

www.webx.dk/rc/video-wireless/2007-03-20-500mWcomp.wmv

here with 500mW power

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Thanks for the replies. I will look for the needed sma connectors and short coax cable. I may try soldering the existing lead to the patch and see what I get. I might just make both antennae shown here and give feedback as to my results.

Thanks again and if you can point me toward parts sources I would appreciate it. I saw in the other thread regarding this project that Amphenol makes the sma connector you recommend Tom (if I may). I think I traced that to Mouser. I'll look again. They will more than likely have the coax also.

Is it possible, and if so, wise, to remove the can from the pcb and put a male sma on the can and attach it directly to the patch and then reconnect the can to the pcb with soldered wire? Sorry if thats a stupid question. I don't have it in front of me and am throwing out thoughts.

I appreciate the help.

Rob

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yes ! a direct connection using only connectors is what you need !

NO coax cable,

why: if you have mis-match in the RX side or antenna, the signal will be reflected in the coax.

mount a FEMALE SMA to the cans of both TX and RX,

on the RX side mount a MALE SMA on the antenna, so it fits perfectly directly on the RX.

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This looks like it would work. This soldered to the rx can... (the images link to the Amphenol spec pages)

132203.jpg

...and this on the patch (as mentioned in a similar thread)...

028.1.jpg

I think I need the right-angle fitting on the rx because of the location of the can (see the images in the first post). I like the fact that it is a bulkhead fitting so I can bracket it to avoid strain on the solder joint. Tom or Mr.RC-Cam, if you could verify that these two will mate with each other I would appreciate it.

Any other suggestions are truly appreciated.

Rob

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>if you could verify that these two will mate with each other I would appreciate it

you have got a GO !

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My sma connectors are slated to arrive on 3-30-2007. Just in time for the weekend.

Tom - how critical is the thickness of the copper and aluminum plates? My local hardware store carries copper that is .025 inches (.635 mm) thick. This is a little thicker than what you specify in your diagram. Is it important?

Thanks,

Rob

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Rob, I have so far only made one of this type of patch,

so I dont know for sure about the material thickness,

I suggest you try to keep it all as close as possible,

the air gab is the most critical, be sure it is right.

I used a benchgrinder to fine tune the plates into right size,

it also ended up making them look really nice,

since it was a few mm too big all over,

so maybe that is a god way to get cutting/sawing marks away.

I will need one more patch next week when my new diversity rx shows up,

and I need to check out the 5.6Ghz links one of those weeks to come I think,

so I need to make a few more.. but my OSD project is SOOO much fun right now.

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OK - here are the "after" pictures. I did Tom's antenna first. The bottom plate is aluminum with a mirror finish. It didn't cost any extra so I thought why not. The top plate is copper. I used a right angle sma on the receiver soldered directly to the can. That went surprisingly smoothly. Everything lined up beautifully. I used 4mm nylon spacers, scuffed and epoxied, to set the gap.

I tested it briefly in the house and it worked. I was surprised that I could go from the basement to the first floor without much interference. I thought it would be much more line-of-sight. Signal must be bouncing around and coming up the stairs. I don't know.

We're in the middle of a mid-April snowstorm here in Wisconsin so it will be a couple of days before I can flight test.

patch1.jpg

patch2.jpg

patch3.jpg

patch4.jpg

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Hey Rob, Thomas,

I like all the experimenting which is going on here with the patch antenna.

As well as with the lower end receivers. I use the plural since I have one also. Not the same brand as what Rob is showing here but the receiver can inside looks darn similar to the one I have.

Receiver1.jpg

I have the patch pieces cut and ready to assemble, connectors will be here tomorrow.

I will install the receiver connector in the same fashion as Rob.

After pics and and a comparison of the junk dipole to the patch as well will follow.

Edited by IndiQa

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