Building an Airband Antenna

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matt_wi

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I am using a software defined radio and am looking for a good (and cheap) airband antenna to hook up to it. The antenna is most likely used indoors and with 10-15 miles of airport. I'm even willing to build an antenna if that makes more sense. I also need to be able to move it easily. Since I have to move it from home, to the office, to school. Any help would be greatly appreciated. Thanks so much.

Matt
 

shaft

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Take as look at the Maldol AL-500H, its an antenna specific for the airbands. It works great for me in doors, I also use the Diamond RH77, and RHF40 with similar results.
 

matt_wi

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Any ideas on how to mount the Maldol antenna? Is there a mag mount or something I should use?
 

iMONITOR

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Take as look at the Maldol AL-500H, its an antenna specific for the airbands. It works great for me in doors, I also use the Diamond RH77, and RHF40 with similar results.


+1 for the AL-500H, and RH77. Haven't tried the RHF40.
 

smason

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For just air-band and only 15 miiles, I would think a simple 1/4 wave ground plane would work well.

Costs almost nothing, easy to make, not that big.
 

matt_wi

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Anyone have any idea on how well these work with the USRP? I'm afraid that I'm not going to get enough signal strength and I'm going to be hurting now matter what antenna I get.
 

matt_wi

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For just air-band and only 15 miiles, I would think a simple 1/4 wave ground plane would work well.

Costs almost nothing, easy to make, not that big.

any good recomendations on where to get instructions on how to build one? Remember it has to work indoors.
 

DickH

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any good recomendations on where to get instructions on how to build one? Remember it has to work indoors.

Vertical element = 23", the other 4 = 24" for 120MHz

27104369.jpg
 

DickH

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And what are all those parts? Looks pretty impressive to me :)

Length in inches of the vertical element:
462 divided by the freq., then divide by 2, then multiply by 12.
Multiply by 1.05 for the radials.

"all those parts" is an SO-239 connector (Radio Shack #278-201). You can solder to it, omitting the nuts & bolts.
Use #10 house wiring or welding rod.
 

mass-man

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Or metal clothes hanger rod if you can still find it. I have built COUNTLESS number of antennas just like this thru the years. 2 mtr. ham, airband, VHF monitoring, 220 mhz, and the list goes on. Two years ago I was working at a major news event and the local cops were using simplex just over the side of the hill for communications. I built one just like this for 155.450mhz, put it on a 8 ft. light stand on top of the RV and we could hear everything!!! They work, they are easy to build and the formula will work for almost any frequency you might need.

Build one, it is easy, cheap and you will have DIY!!!

cleve
 

W6KRU

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The length of the radials is not critical if you make them at least 5% longer than the vertical. You can't make them too long.
 

matt_wi

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Thanks again for all your guys' help. I am hoping to build the antenna this afternoon now that I have all the parts.

Can anyone recomend a good way to convert from the so-239 connector to an sma or standard coax (like my cable tv has)?

Sorry for all the newbie questions but i'm a novice when it comes to antennas to say the very least.
 

jack103

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I am using a software defined radio,so why Mickey Mouse the antenna?
Million dollar receiver and a 2 bit antenna makes no sense. Invest in quality cable and antennas!
 
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matt_wi

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I am using a software defined radio,so why Mickey Mouse the antenna?
Million dollar receiver and a 2 bit antenna makes no sense. Invest in quality cable and antennas!

Because this is a project for a class and I don't want to dump a ton of money (the USRP is on loan from school). I'm going to build a 1/4 wave ground antenna today and see how it works.
 
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