how do you make a "loaded aerial"?

betty.k · Post by **betty.k** » Tue Jul 25, 2006 5:12 pm

a loaded antenna is an antenna that looks electronically large while being physically small

eg: a 27 mhz aerial should be around 11m to match the frequency. 1/4 of this is an accepted length.
but that still leaves you needing an aerial over 2m (like 6ft).
a 27mhz loaded antenna would be only a few inches in length physically,but electronically would look like an 11m one.

i wanna make one for my heli which is 35mhz.

when i searched on google all i get is links to sales for built ones, i'm hoping i can make my own with what i got.

so can i? or will i need to buy a loading coil and use an oscilliscope (sp?)

evoraptor · Post by **evoraptor** » Tue Jul 25, 2006 6:38 pm

Hope this helps..

http://xmodworld.com/modules.php?name=F ... pic&t=5432

It's for an Xmod, but yea, should work for all scales.

beanoman · Post by **beanoman** » Thu Jul 27, 2006 1:15 pm

Hmm.. Well, 1/4 on 35 as you said is about 2m or 7 feet. 1/4 on 72 is about 3.4 feet or 41 inches so we're off easier over here for using straight antennas. Anyways, as far as base loaded antennas.. All I've read in all my airplane-forum-reading history(:lol:) Is that base loaded gives you a lower range than most any antenna that is straight.. even a 19 inch straight antenna(yank 1/8 wave, on gws-ish rx'es) will give more range than some, or even most base loaded antennas.

So, after ramblein on about whatever, your goal is range and the needs are lightweight for your heli.. it sounds kinda 'unprofessional' but i think your best bet is dangling 1/8 or 1/4 wave of cat-5 wire from your heli.. I just had to cut open a new cable for some more wire, and weighed a 6 foot piece(all the cables are 6 feet, instead of the 7 you need, lol....) and it was only 2.5 grams so you should have no problem dangling a 7 foot piece from your choppa.

Another thing is that '''cheap''' recievers like whats in the rtf helis we fly will take more interference from other stuff if they are too sensitive, which then might give you less range even with a 7 foot 'tenna.

I'm sure you have, but tried just dangling the stock antenna yet?

Didn't really answer your question, but might help..

betty.k · Post by **betty.k** » Thu Jul 27, 2006 4:46 pm

actually, i haven't tried just dangling the aerial. i'm too scared of it catching on anything!
and i'm sure there's no problem with it being around the boom so i've just left it.

i'm also using enamelled copper wire for the rx aerial, maybe that's bad.
2.5g is nothing compared to the camera and extra battery it can already carry so i'll try a 1/4 wavelength aerial next using some proper wire.

i just thought that a loaded aerial would be better for range, the fact that it's small isn't an issue for me.

beanoman · Post by **beanoman** » Thu Jul 27, 2006 6:22 pm

Ok, from my experiences and a few things i've read- the enamel wire needs to go, and the new wire needs to be straight. When I was running my camera truck from inside, i could only get the truck down the driveway with the antenna coiled. after i strung the tenna up on a big balsa stick, as far as it could go, got down the driveway, across the street, down a house or two, and down theyre driveway... pretty far away, and through a few walls, lol.

so i think you should really try it with it hanging down- i think since its just a hanging wire it will just drag over stuff rather than getting caught on it.

1/8 may give you enough range, 3.5 feet or so, maybe give that a try before you do 1/4 which may pick up too much interference.

as you said, the 2.5 or whatever grams wont make any difference.