I have been wanting to try  using alternative antennas on the 2.4 G  fatshark  like the long range 9 dbi one available in the market  till the 500 mW Tx  comes along and got my self all confused reading up  .

I have come across very  funny inputs :

5 dbi antenna  gives shorter range than the 3 dbi antenna  in case of flying in general  as there is some  talk of  the power being more directional specific in case of higher power antennas  and that  higher power could also amplify existing 2.4 G interference  along with the Video feed  thus giving the impression that range is less  and causing interference etc .

I wonder why  a more powerful antenna should  not give a longer range of reception.

I was just thinking that with my existing 10mW Tx  I could get a higher range  with a  more powerful antenna  .

BTW what is the full form of " dbi " and what do all these numbers like 3dbi, 5 dbi, 9dbi all mean .

Can I use any 2.4 G antennas available in the market  or THAT WHICH IS A SPARE FOR A 2.4 g RADIO  ETC on any 2.4 G  system to increase range  like the ones available on  ebay  ?
http://shop.ebay.in/?_from=R40&_trksid=p3907.m38.l1313&_nkw=antenna&_sacat=See-All-Categories

If yes then can they be used  externally  for a 2.4 g radio's  as well  to extend their  range .

Sai

Sai,

The world of antennas and RF propogation is a complex science. In RF there are so many parameters that can easily go wrong, so, its not so easy to design something off-the-shelf without the vendor/manufacturer recommendations. If you have the background in RF then its a different scenario.

Now, Dbi means a way of measuring the antenna gain with respect to a theroritical (ideal) antenna called the isotropic antenna (thatz why the 'i' is for). I think the various forms of dB measurements itself is very confusing (at least for me). check out -> http://en.wikipedia.org/wiki/Decibel

The simple answer for trying out the 2.4G antenna is -> I don't know.

But I would check few RF parameters like impedance matching and the wattage handling of the antenna, which I guess is not your cup of tea. However, I would go ahead and hook up the antenna and just have a finger on the TX output circuit to check if there is any excessive heating. Just do not run it for a long time. Note that improperly matched antenna WILL damage the TX circuit over a long period of its usage. (Just like running the rc transmitter with antenna collapsed)

-Ismail

My Tx will be on board the plane and the Receiver is in my goggles  and it is the receiver antenna I am thinking of trying the more powerful antenna on , so  will checking the heat of receiver be OK.
sai

Sai

What you are looking for is a more sensitive antenna for your Rx, i.e. one with higher gain than the present one.

The receiver will be unaffected.  What izmile was referring to is the Tx. A mismatched antenna can can cause serious problems, even damage, to the output stage.

So, for the Rx, feel free to experiment. You have nothing to lose but your time!

Sushil ,
In the case of the FPV the position of the receiver and Tx are reversed the Tx is on the plane and it is low power 10 mW type.
The receiver is in the Goggle on ground so what I can fiddle with is the receiver on the ground , I guess no point trying to Mod the Tx as it is limited by its transmission power of 10 mW. So till I get my 500mW tx all I can do is try to boost reception.
This is what I was thinking of doing.
Range test the 10 mW Tx  last week end and best I could get with reasonable clarity is around 250 -300 m after which the Image clarity drops drastically.

BTW flying FPV was a different experience it is much easier to get orientation from the plane if you know the topography of flying field well.
The reversal of controls when the aircraft is flying back to you is not a problem you just steer the aircraft like you would to a car based on your judgement from within the plane.

sai

You are on the right track in getting the higher power tx. From my experience with similar powered transmitters (There used to be a bunch of vendors selling wireless video cam + rx for less than Rs1500 on ebay India about 4-5 years back. They used to be of similar power.), whatever improvements you make on the rx ant side, it is still not enough for reliable interference free video. Higher gain antennas are also more directional. You'll need antenna to track the plane if you go this way. Still, 10mW is not enough.

Also when you get higher powered tx/rx, try to avoid getting them in 2.4G. Some of them overloads the 2.4G Rx front end and you'll lose control over the plane.