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LoopForEver

Length of TX antenna for Airwave module?

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Hi,

How long do the TX whip antenna need to be, to get best result?

1/2, 1/4, 1/8? (With Airwave 450mW and 10mW module)

What wire size(mm2) to use - don't matter?

Example for CH4:

300/2468=0,122*0.25=0,03039

So about 30,39 mm for CH4?

Right now i have just soldered a 0.25mm2 wire to the RF out pad,

length=30mm, with no SMA or COAX or Shield, just connected directy - vertical.

ok?

Its a Ground Plane better?

http://www.yb2normal.com/antenna3.html

LoopForEver

Edited by LoopForEver

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1/4 of a wavelenght * 0.9 = the wire you need

use a wire that is thick and stiff so it will stay straight,

but not too stiff so the board will brake if you touch it,

alternative strongen to solder mount point with hot melt glue.

0,03039 meters is 30,39 mm

but remember the shortting factor 0.9

use 27mm wire.

the whips are longer = more gain and more zero in the ends,

a 1/4 wire have less gain, and less zero in the ends.

Edited by ThomasScherrer

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>1/4 of a wavelenght * 0.9 = the wire you need

>use a wire that is thick and stiff so it will stay straight,

>but not too stiff so the board will brake if you touch it,

>alternative strongen to solder mount point with hot melt glue.

Done that, so thats good :-)

Its it better to point antenna down under the plane(vertical),

than upwards?

Some years ago i builded a Ground Plane ant for the cheap CMOS china systems,

and it worked better than a simple whip.(But not if plane is just over ant!)

>0,03039 meters is 30,39 mm

>but remember the shortting factor 0.9

>use 27mm wire.

The need to multiply with shortting factor is because speed of light is slower in air,

+freq adjustment + PCB track - right?

>the whips are longer = more gain and more zero in the ends,

>a 1/4 wire have less gain, and less zero in the ends.

So a 1/2 wavelength will be better for FPV - or just the same?

My Airwave 450mW TX have just died :-(

Do not really know what went wrong, maybe the Linear reg, got in a hot runaway condition, and just gave more power than 3.3V to the RF stage..but it did not seem to run very hot - just suddenly died, after a FPV flight.

(Can see on RX when power to the TX, but just noise/lines, and a very bad grey cam picure flikkering - RF stage dead?)

Using my low power Airwave 10mW TX module insted, but have alot of dropouts -but works.

LoopForEver

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