5db Antenna for FrSky module

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5db Antenna for FrSky module

Postby Evan » Wed Aug 11, 2010 9:52 pm

I am thinking of getting a 5db antenna to fit onto my FrSky DFT module that is currently in my Eclipse. Apart from being a bit more sensitive it is also longer as well. The stock 2db antenna only just makes it above the top of the transmitter casing and if I am holding it in my hands horizontally (as you would when controlling a model) I am concerned that the RF signal from the TX will be less than optimal.

I have already modded the casing on the DFT so that the 2db antenna is now pointing upwards. On the Hitec TX's the module slot is upside-down as opposed to the Futaba TX's for some reason. Does anyone know what the FrSky antenna connection type is? I am aware of RP-SMA but these are too big to fit on the FrSky.

Also, is it possible to move the antenna so that you could fit it to the top of the TX? Is there a kit you could install to allow you to extend the wire out of the back of the FrSky module and onto an antenna glued to the top of your TX?
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Re: 5db Antenna for FrSky module

Postby RCModelReviews » Wed Aug 11, 2010 10:04 pm

I wouldn't recommend the 5dBi antenna.

For a start, it obtains its extra gain by simply robbing power from some aspects to add to others.

All dipole antennas have a null-spot at the end where the amount of radiated signal is much lower (which is why you're told not to point the transmitter antenna directly at the model when flying). The 5dBi antenna has an even larger, deeper null-spot than the regular (2dBi) antenna so that will exacerbate the risk.

The FrSky radios have a huge amount of headroom in respect to range so you'll be gaining nothing by using the 5dBi unit.

Don't worry that the antenna doesn't poke up above the radio, that won't hurt. I've use the FrSky modules in my E7 and O6 with no issues at all.

If you want to do a permanent conversion you can mount the 2dBi antenna in the hole where the telescopic one used to go and use a longer cable to the module but, to be honest, I think you'd be better off using a DIY kit so you can mount everything internally if that's what you want.
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Re: 5db Antenna for FrSky module

Postby Evan » Wed Aug 11, 2010 10:50 pm

Ok, I will leave it as it is. I have heard of the null-spot before but with the FrSky module in the E7 you are constantly pointing the antenna towards the model as you are holding the TX horizontally and you are always facing it. With my DX6i I can orientate the antenna 90 degrees to the TX so the model is always within the toroidal radio emmission. I guess some sort of mod to extend the antenna to the top of the TX could be done.

Thanks for the advise Bruce and if you haven't had any problems with the stock antenna then it looks like I have nothing to worry about!
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Re: 5db Antenna for FrSky module

Postby RCModelReviews » Wed Aug 11, 2010 10:54 pm

You don't have to position the transmitter antenna straight up -- you can bend it to the side if you want. Some people prefer to fly with the antenna bent to the side so that it's never pointing directly at the model. This may require you to unscrew the antenna, bend it, then screw it back on with some radios because otherwise the handle gets in the way.
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