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jtprouty

Quick 900MHz RX Antenna?

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Hi All,

Well, I seem to have lost my 900MHz dipole receiver antenna :( and need one for this weekend. SuperCircuits website is "down for maintenance" so I can't order one at this late date. Anyone know how an electronically challenged person can make one? I don't have to have fantastic range for it as my flights will all be with 1/3-1/2 mile from the takeoff point.

Any information will be GREATLY appreciated. :D

Thanks in advance,

Jim Prouty

Edited by jtprouty

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You might want to try this groundplane antenna: http://www.transmitvideo.com/antenna.html

You will need to rescale it for 900Mhz. The driven radiator and the four radials would need to be 80mm long. Construction would be similar to YB2normal's PCB solution: http://www.yb2normal.com/antenna3.html

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Yes, but you would probably experience better overall Rx performance with a patch antenna. The GP Patch could be rescaled for 900Mhz. Just multiply ALL dimensions by 2.67.

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Great! :D

Will order the SMA tonight and build the patch next week. Will try the ground plain antenna for this weekend until the SMA connector comes in.

Thanks again!

Jim

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Ok I'm jumping on this old hread here since it's related to my question. I just ditched my 2.4ghz stuff in lue of some new fancy shmancy 900mhz from futrehobbies. I DID build and use the "GP patch" for my 2.4ghz equipment and it really helped. I know the directions say you can scale everything to work for the 900mhz and my only question is weather or not that applys ALSO to the spacers between the two elements of the antena. Basically the orignal plans call for a 0.2" spacer. So if I multiply that by 2.67 the new spacer length should be 0.534" is that correct?

Thanks!

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The scaling applies to ALL the dimensions, including the air dielectric spacers.

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Woo Hoo! I'm off to the garage. Thanks for the fast reply Mr.RC-Cam. Are you a electrical engineer by trade? How did you come to know so much about this stuff and how to make it your self?

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How did you come to know so much about this stuff and how to make it your self?

Like some of you, I'd rather make this stuff myself. So, that personal philosophy is what gets the ball rolling on the various things you see on the rc-cam project site. The rest is just solder and sometimes binary numbers organized in neat little rows. :)

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OK is this for real. Enlarging the GP-patch specs for 900mhz my reflector is going to be over 10 inches square and the element is going to be about 5.5 inches square?

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It will be a little bit bigger than that, but you have the right idea. There is nothing special about the math: 2.4Ghz dimensions x 2400/900 scaling = new 900Mhz dimension. The project has a FAQ that tells the whole story.

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I actually did the calculations on 980Mhz since that's chanel 2 on the TX RX I'm getting. I though I should try for a frequency closer to the middle of the choices I'll have that way it will work ok with the other higher frequencys and one lower. I hope that thinking was right since I already cut out the sheetmetal...........and using my China made aviation tin snips is sort of a pain.

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