Should I care about the antenna's length if the gain and antenna type are right? 1

[jimbojohn]

Hi all ,

Recently I bought a 2.4 GHz wireless Xbee PRO module with a RP-SMA connector. Previously I was using a 2.4 GHz Xbee PRO which had a small black antenna attached to it and I was receiving signals from an identical Xbee module. I had bought this Xbee from Sparkfun:

Link

My plan was to replace this module with the RP-SMA compatible module and attach an Omni-directional antenna with a higher gain to it so I can extend the range of signal reception (both Xbees were used for receiving signals). After attaching the antenna and testing the RP-SMA Xbee, I realised that the range had increased. When I was searching to buy an antenna I did not consider the length of the antenna at all, but mainly its gain was my focus.

Now, my question is if the length of the antenna is important, how important is it? Do I need to consider the length as long as the antenna is an RP-SMA antenna and has the gain I want?
My other question is if I want to use an SMA antenna extension cable like this one to put my antenna away from my Xbee module:

[link

http://www.jaycar.com.au/productView.asp?ID=WC7800

]Link[/url]

Do the same length criteria or limitations apply to this cable length too or not? In other words for example if I have a 1/4 wave antenna, does adding this extension change that length?
I have calculated that I will only have around 1.5 dBi signal loss which is fine by me.

Many thanks in advance

 

[IRstuff]

??? The antenna length is part of what makes up its gain

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[VEBill]

"...an Omni-directional antenna with a higher gain..." is probably a collinear antenna array.

Google up some images of 'collinear antenna' and you'll begin to see how the length (height) of the collinear antenna implies more elements, and thus more gain (while remaining omnidirectional in the azimuth).

 

[jimbojohn]

Thanks a lot guys . So just to clarify my doubts, is the length of the extension cable provided in the second link going to have any other effect on signal reception other than a bit of signal loss which I have calculated? Because I just want to use that cable to put the antenna away from the Xbee wireless module.

 

[IRstuff]

The length of cable is presumably shielded, and does not act like an antenna, unless something is wired wrong.

TTFN
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[jimbojohn]

Thanks. That makes sense.

 

[vertical77]

If you have a 1/4 wave antenna, this extension cable does not adding change that length. Cable is not an antenna.

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