Indoor Antenna for ATC and MIL Air Traffic

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ChargerF18

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Hello All,

Going to try and keep this as simple as possible, I have no idea how to build an antenna but am willing to learn and try....but I currently rent my home and cannot drill or mount any external antennas. So any antenna that is either made or purchased needs to be smaller in size, but I have an Icom R5 and have a SRH-77CA....and when putting the scanner on top of my kitchen cupboards and or above the cupboards I get better reception. In a cost effective way what are my options for building something or purchasing something is an option also to use indoors? The frequencies I use the most are low 100's(my local airports ATC are 119.6 and 119.4), up to higher MIL Air Traffic in the higher 300's(396.9 is one I use a lot of). So I would think 100-500mhz, that would be suffice!! Hope this all makes sense, thanks in advance!!

Luke


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cmdrwill

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Start out with a simple 1/4 wave ground plane made on an SO239 coaxial connector. About 22 " on each of 4 radials and vertical center element.
 

popnokick

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This antenna works quite well indoors if you hang it in an upstairs window (or as high as you can get it in the building). The wire version (scroll down the Wiki page to see it) costs about $10 and 20 minutes of your time to make with parts from any home store / hardware store. The antenna is written about extensively here on RR (search "OCFD") -
Homebrewed Off-Center Fed Dipole - The RadioReference Wiki
 

SCPD

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Off the top of my head, I would suggest a turnstile antenna. They can be mounted indoors, close to the ceiling, without being obtrusive.
Granted you won't find the perfect antenna, a half-wave turnstile with a design frequency of 126 MHz would be close to resonance with the lower frequencies stated, while its third harmonic would be close to the mil-air frequency listed.
Turnstiles tend to be a little more noisy than directional antennas, but might be a suitable compromise for your situation. There are many designs available on the web.
Good luck.
 

ChargerF18

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Start out with a simple 1/4 wave ground plane made on an SO239 coaxial connector. About 22 " on each of 4 radials and vertical center element.


Could you show me an example or post a link to one...I'm new to all this building antennas and have no clue, where to start and what to use. Thanks for the input!


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ChargerF18

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This antenna works quite well indoors if you hang it in an upstairs window (or as high as you can get it in the building). The wire version (scroll down the Wiki page to see it) costs about $10 and 20 minutes of your time to make with parts from any home store / hardware store. The antenna is written about extensively here on RR (search "OCFD") -
Homebrewed Off-Center Fed Dipole - The RadioReference Wiki


Ok, interested in building this, few questions tho....what size wire do I use? Also what is the exact name of the transformer and would Home Depot/Menards carry them? I have a SMA connector for my scanner what adapters will I need to connect the coax to my scanner, with that being said what coax cable is the best to run to my scanner from the antenna......and Lastly, does anyone have any pictures on the proper way of hanging this antenna and what is the best way to adjust them to find the best angle for best reception...

I guess that was a lot of questions....sorry! Thanks again for the input...

Luke


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popnokick

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..what size wire do I use?
Assuming you are referring to the wire version (not the copper pipe version). Any hookup wire will work... probably at least AWG 20 or larger.
what is the exact name of the transformer and would Home Depot/Menards carry them?
Home Depot calls theirs "Channel Master Outdoor Transformer Balun". Menards has two in the TV Antenna section: "RCA Indoor Transformer" and "RCA Push-on Transformer". These are 300 to 75 ohm matching transformer / balun. The feed point of the antenna is 300 ohms and must be matched to the 75 ohm coax that you will use. Use an F-female to SMA male adapter or pigtail to attach the other end of the 75 ohm coax to your scanner. You'll probably have to order the adapter from Amazon or someplace that has them. Here is one of many available -
https://smile.amazon.com/uxcell-Female-Coaxial-Antenna-Adapter/dp/B008MN4TDQ/ref=sr_1_8?s=electronics&ie=UTF8&qid=1480678455&sr=1-8&keywords=f+female+to+sma+male
what coax cable is the best to run to my scanner from the antenna
As the Wiki states, 75 ohm TV coax cable. Since you are going to use the antenna at UHF (Milair) freqs, stick with a good grade of RG-6... even quad shield. Yes, 75 ohm coax works fine with scanner receivers.
what is the best way to adjust them to find the best angle for best reception...
No adjustment needed... the antenna is omnidirectional. But hang it vertically from one end of the wire as explained in the Wiki, and run the coax away at 90 degree angle. Be certain you use the lengths of wire specified in the Wiki.
The rest of the answers are in the Wiki.
 

ChargerF18

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Assuming you are referring to the wire version (not the copper pipe version). Any hookup wire will work... probably at least AWG 20 or larger.

Home Depot calls theirs "Channel Master Outdoor Transformer Balun". Menards has two in the TV Antenna section: "RCA Indoor Transformer" and "RCA Push-on Transformer". These are 300 to 75 ohm matching transformer / balun. The feed point of the antenna is 300 ohms and must be matched to the 75 ohm coax that you will use. Use an F-female to SMA male adapter or pigtail to attach the other end of the 75 ohm coax to your scanner. You'll probably have to order the adapter from Amazon or someplace that has them. Here is one of many available -
https://smile.amazon.com/uxcell-Female-Coaxial-Antenna-Adapter/dp/B008MN4TDQ/ref=sr_1_8?s=electronics&ie=UTF8&qid=1480678455&sr=1-8&keywords=f+female+to+sma+male

As the Wiki states, 75 ohm TV coax cable. Since you are going to use the antenna at UHF (Milair) freqs, stick with a good grade of RG-6... even quad shield. Yes, 75 ohm coax works fine with scanner receivers.

No adjustment needed... the antenna is omnidirectional. But hang it vertically from one end of the wire as explained in the Wiki, and run the coax away at 90 degree angle. Be certain you use the lengths of wire specified in the Wiki.
The rest of the answers are in the Wiki.


Thank you very much!!



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prcguy

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A turnstile is typically horizontally polarized and aircraft is vertically polarized, I see a bit of a problem with that for the OPs purpose.
prcguy

Off the top of my head, I would suggest a turnstile antenna. They can be mounted indoors, close to the ceiling, without being obtrusive.
Granted you won't find the perfect antenna, a half-wave turnstile with a design frequency of 126 MHz would be close to resonance with the lower frequencies stated, while its third harmonic would be close to the mil-air frequency listed.
Turnstiles tend to be a little more noisy than directional antennas, but might be a suitable compromise for your situation. There are many designs available on the web.
Good luck.
 

K4ROV

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Roanoke, VA
Ok, interested in building this, few questions tho....what size wire do I use?
I made a "shortie" OCFD with electrical wire (24" and 9" legs). It's stiff enough to support itself from the balun. A paint stir for the boom and it fits in the window well of my sliding glass door. It's supported by an old speaker stand and hides behind the curtain.

It does remarkably well at 400 and 800. I can hear two counties over in mountainous southwest Virginia.
Strictly an experiment with parts at hand, but I'm happy with it until Spring.
 

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popnokick

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K4ROV- Thanks for the pic and the report!
ChargerF18 - Don't cut yours short.... follow the lengths in the Wiki, or you will reduce your VHF aircraft band reception considerably.
 

ChargerF18

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I made a "shortie" OCFD with electrical wire (24" and 9" legs). It's stiff enough to support itself from the balun. A paint stir for the boom and it fits in the window well of my sliding glass door. It's supported by an old speaker stand and hides behind the curtain.



It does remarkably well at 400 and 800. I can hear two counties over in mountainous southwest Virginia.

Strictly an experiment with parts at hand, but I'm happy with it until Spring.


One question, what gauge wire did you use so it was able to hold itself? Thanks for the pic and the report....looks very simple!


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ChargerF18

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K4ROV- Thanks for the pic and the report!
ChargerF18 - Don't cut yours short.... follow the lengths in the Wiki, or you will reduce your VHF aircraft band reception considerably.


Will do, thanks for the heads up, that is the main goal of all this is to pick up more AIR AND MIL AIR frequencies!!


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popnokick

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ChargerF18- If your intent is to make an OCFD that is "free standing" you're probably better off making the copper pipe version. #10 or #12 gauge wire is going to get a little crooked trying to keep it upright with one of the elements being 48". If you use hookup or bell wire from about 14 to 22 gauge you simply hang one of the elements vertically and if you have to, use a non-metal weight or fasten down the other end. Run the coax away as close to 90 degree from the elements as you can.... for as far as you can, but at least about two feet. Nice thing about the wire version is you can take it down, roll it up... and travel with it anywhere. Just hang it up in as high a window / balcony you have.
 
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