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ThomasScherrer

Quadrifilar for RX

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Hi I wanted to hear if anyone tried to compare a Quadrifilar vs a Patch ant,

for RX on 2.4GHz video links ?

here you can read about a Quadrifilar for GPS:

http://www.ien.it/~brida/LNAGPS.htm

but they can ofcorse also be made for 2.4GHz if we like.

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I don't think it will be good for the RX but it would be good for the TX.

I was looking at making one for my UHF R/C TX but it's only at the idea stage so far.

Terry

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I agree, it may be a good idea for TX antena. I haven't tried it, but CP property is always nice to have for the downlink.

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The Quadrifilar will pick up signals from every direction to a greater degree than a standard whip or dipole. This means it will pick up more noise and less of the wanted signal, just the oposite to a patch which can be aimed to pick up more of the wanted signal. The Quadrifilar would be good for the TX as we want to transmit the signal in every direction so we reduce drop outs. The main advantage would be that there is no dead spot at the end of the aerial so when overflying or turning so that the bottom of the plane is ointed at the RX aerial no loss of signal would result (if Quadrifilar mounted under plane).

The other advantage is that (I believe) it has circular polarisation so it should not cause the received signal to drop in turns.

The only time I can see the Quadrifilar being of any advantage on the RX is when flying very close and doing aerobatics round the RX.

Terry

Edited by Terry

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Thanks for your input Terry, I appriciate it.

I will see if I can find any scaled drawings for 2.4GHz online ??

any seen them ??

or else I have to scale it my self, I have access to network and antenna analyzers,

so the construction and test and adjusting is possible for me,

and then I will see if I can make a few test flyings,

and then compare the video recordings,

this ant will be quite small for 2.4

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OK Thomas, I look forward to seeing your results. I for one would like to use one on my plane :)

Terry

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very pretty if nothing else. Plate it in gold, use it in the next Bond movie. Secret agent video antenna/cocktail mixer ;-)

Getting those bends just right will be tricky without the proper test gear, but it would be nice to get better distribution.

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hi Lupy if you look in the docs available on this topic online,

there is a wooden stick with holes you will have to make,

and then just wound up the wires on that stick, now they are all perfect.

But If I did not have access to test equipment I would never start constructing antennas for such hi freq bands, just a few mm off and the antenna is only a funny sculpture of no use at all :-) oh sorry a cocktail mixer is a perfect usage for all the mismatched experiments :-)

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The quadrifilar working great on my tx and on my rx on my plane with only 100 mw , no need too track the plane that is better when you made fpv flight

the quadrifilar is hard to build correctly without test equipement, but I think this aerial is great for our hobby

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What dims. did you use? Any chance of making a GPP style design for these? For those of us without test equipment.

Also, what range are you getting? how about dropouts?

Thanks

Ken

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This thread seesms to have gone quiet, any news ?

The quadrifilar working great on my tx and on my rx on my plane with only 100 mw , no need too track the plane that is better when you made fpv flight

Details and pictures please <_<

I will see if I can find any scaled drawings for 2.4GHz online ??

any seen them ??

or else I have to scale it my self, I have access to network and antenna analyzers,

so the construction and test and adjusting is possible for me,

and then I will see if I can make a few test flyings,

and then compare the video recordings,

this ant will be quite small for 2.4

Any update Thomas ?

Terry

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Hi terry, the update is I have found the parts needed,

but I did not find a nice scalled drawing,

and I have been too lazy/busy to scale it my self :-)

I am playing arround with 10 other things right now that is super cool and funny.

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