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Airband Antenna Question

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jbaime

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Jun 6, 2006
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I have always been an air traffic enthusiast. I recently got a scanner and I really like listening to the traffic live. I live in Metro Atlanta so there is a lot of airband activity. I live about 10 miles from the airport. I can hear the planes, but never the tower. I can hear high level air traffic (30,000 feet+) at a distance of up to 90 miles. I'd like an antenna that would:

1) Enable me hear the Atlanta tower (10 miles) and Atlanta Center (I believe at a different location that transmitts 20 miles away in Hampton, GA).

2) I would love to be able to hear high altitude aircraft from much further away than 90 miles.

How much of this can I accomplish with a hand held antenna? Is there one anyone could recommend? Would a rooftop make a substantial difference in hearing the tower or distant high altitude aircraft? I don't want to spend the money to have one mounted if there isn't much of a difference between a good handheld and a rooftop antenna. My assumption is that any aircraft radio transmitting from 6 miles up should be heard with the help of a good antenna from much further than 90 miles away.

I live in an area that is not really blocked by hills, although there are a lot of trees around.

Thanks.
 

ka3jjz

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Bowie, Md.
Your pushing the limit insofar as a handheld antenna is concerned. There's just no way you're going to get 90 mile range on one - there's simply too many obstructions (not to mention any attenuation from your own body) even with a good handheld antenna like the Maldol that has been mentioned in the other forum (and is found on our Scanner Antennas wiki).

The good news is that a simple ground plane, mounted nice and high, will help greatly (depending on your surrounding terrain - gotta get away from the trees). If all you're interested in is aircraft comms, that will serve your purposes nicely. Not too hard to construct, either. No need to go buy something when the need is very simple.

73s Mike
 

kb5udf

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Louisiana
Suggestions

IMHO, almost any non duckie (ie mobile or base), will handily outperform what you are using now. With a dual band(vhf/uhf) ham antenna in the attic I've routinely gotten 200+ mile coverage, and that's with an antenna not even designed to cover air.

Just about any aviation band magmount on a piece of metal/pie pan, or a basic scanner antenna, like if memory series the ubiqutious RS 20-176 would be a vast improvement, even if it doesn't make it as high as your roof.

Not long ago, I got a mobile 5/8 wave aviation antenna by maxrad on ebay for about $20, with a few homemade wire radials for grounding, it makes a great scanner antenna.

Jean B.
 

jbaime

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Great thanks!

Thanks for the advice. Sounds like picking up aircraft with an attic or roof antenna should be pretty simple!
 

kb2vxa

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Hi J and all,

"1) Enable me hear the Atlanta tower (10 miles) and Atlanta Center (I believe at a different location that transmitts 20 miles away in Hampton, GA)."

Highly unlikely, that 10W into a groundplane or discone isn't meant to be heard by other than aircraft. The power and the antenna's vertical takeoff angle are designed solely for that purpose, not to hug the horizon over any particular distance.

"2) I would love to be able to hear high altitude aircraft from much further away than 90 miles."

So would I but again that's not the purpose, VHF is only meant to be heard within the operational footprint of the tower. They use HF for long distance comms.

"How much of this can I accomplish with a hand held antenna?"

Very little.

"Would a rooftop make a substantial difference in hearing the tower or distant high altitude aircraft?"

Possibly but there is no guarantee. It all depends on the antenna design, a high gain antenna hugs the ground and would defeat your purpose of receiving the aircraft but possibly pick up the tower but again there is no guarantee, especially at the range you stated. One thing for sure, a groundplane or discone like they use at the airport vs. an indoor antenna and especially a duck would make a definate improvement at least with the aircraft.

"Sounds like picking up aircraft with an attic or roof antenna should be pretty simple!"

Not as simple as it sounds, a crane would work better and there is less possibility of damaging the antenna. (;->)
 

KSFY45

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Messages
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I am 110miles due west of O'hare (KORD) and 40 miles south of Chicago ARTCC remote located at Dubuque. I have hills to the east and trees all around. I use a homemade ground plane using a 20 inch element and four 18 inch plane elements bent downward at about a 45 degree angle. Ant is clamped to a 15 foot piece of 1 1/2" conduit (EMT) which is in turn mounted on the side of my masonry chimney. It extends about 10 feet above the chimney cap and is about 45 feet AGL. I hear Dubuque (118.42) consistently and KORD RWY 9 Approach occasionally. One temperature inverted morning I heard Quad Cities (KMLI) (Moline, IL) (45 miles south southeast) tower for about a hour... like it was next door!!!

All this BS really means is: "the higher, the better..."

Regards to all
 

kb2vxa

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Hi K and all,

You made a 2M ham antenna, your elements are too short and the radials too shorter. (Bad grammer intentional.) Make the radiator 24" and the radials 25", you're shooting for 120MHz, not 144.
 

Cagao

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Jun 2, 2006
Messages
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I used to use a standard desktop discone and was in the same situation, only 10 miles from the airport and struggled to pick up the tower, radar, approach, ground, etc.

I just made a simple dipole from some copper pipe, now i get everything perfect, even the ground station at another airport over 100 miles away.

I'm on the 2nd floor of a 3 story flat, so there's gonna be a LOT getting in the way anyway.
 

kb2vxa

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Hi Cago and readers,

Well, THAT I can easily explain. A vertical dipole's radiation pattern is quite different than a discone's having the major lobe hugging the horizon. The discone shoots off a bit higher so while it's great for aircraft it sucks for ground stations. The dipole is a compromise, think of a doughnut lying on it's side and you have the picture. If you slice the doughnut in half flat side down you are looking at the discone's pattern. While not entirely accurate you still have a good visualization without all the complications.

Now visualize that flat sided doughnut flat side up. There you have the pattern of a gain omni which is why they suck for aircraft and excel for ground stations. OK, OK, so it's not that doughnut I sat on in another thread but ATCs spit coffee on the radars and get crumbs in the consoles, not on the chairs. It's a tense moment when two aircraft attempt to land on the same runway from opposite directions.

Hey, if you think I'm joking I nearly witnessed a condition 1 right in the middle of 4R-22L at EWR!
 

VintageJon

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KB2VXA- I wonder if EVERYTHING can be explaoned by donuts... (I'm detecting a trend here with your donut theories...)

Wonderful explanations, Sir!

73's,
Jon
 

kb2vxa

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Hi Jon and The Flying Burrito Brothers,

"I wonder if EVERYTHING can be explaoned by donuts."
Just ask Chief Wiggam.

"Wonderful explanations, Sir!"
Thank you. At least >I< know one end of a doughnut from the other so please go easy on the chief.

One end of a doughnut from the other? DOH NUTS! Oh, that's Homer, never mind.
 

jbaime

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Jun 6, 2006
Messages
4
Thank You All!

Scanning the skies from the Atlanta area. With all your help I am able to pick up aircraft at altitude as far away as 250 miles. Plus tons of traffic going into and out of Hartsfiield-Jackson.

Thanks for your advice!!!

Jon
 

gcgrotz

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Feb 21, 2006
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Charlottesville
Try researching the J-pole antenna, various people make them for ham bands, you can find foumulas for them or maybe one of those people can make one for airband. When made out of copper pipe and properly weatherproofed they last forever and work well. stick a pipe up above the roofline if possible.

If you want to experiment, I've seen them made out of twinlead, easy and cheap, and you can roll them up and tape it to some pvc pipe for portable use.

Have fun, but watch the doughnuts!
 
N

N_Jay

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Get a 3 or 6 db Cardioid pattern antenna.

Mount it on a rotor with the antenna leaning by the amount of the 3dB beam-width.

Have fun!
 

gcgrotz

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I found the article I was looking for --- Jan 2006 Popular Communications "KB9VBR's All-Copper J-Pole Antenna"

If you're interested, his web site is www.kb9vbr.com and he sells models for RR, marine, and airband as well as ham bands, GMRS and LPFM. Probably would make one for UHF air if you asked. He also has plans in PDF format to build your own, maybe scale it up for airband.

Heck, I'm all fired up now, I think I'll go to Lowes'
 

K9GTJ

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Kokomo, IN
gcgrotz said:
I found the article I was looking for --- Jan 2006 Popular Communications "KB9VBR's All-Copper J-Pole Antenna"

If you're interested, his web site is www.kb9vbr.com and he sells models for RR, marine, and airband as well as ham bands, GMRS and LPFM. Probably would make one for UHF air if you asked. He also has plans in PDF format to build your own, maybe scale it up for airband.

Heck, I'm all fired up now, I think I'll go to Lowes'
Maybe someone could build me an 800 MHz micro J-Pole antenna. ;)
 

prcguy

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Jun 30, 2006
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So Cal - Richardson, TX - Tewksbury, MA
All Discone radiation patterns I have seen show a low angle of radiation and only get squirrelly at the uppermost range of their bandwidth, maybe 600-800MHz for a typical scanner version. A Discone will work fine for aircraft DX at the horizon and 250mi is about the limit unless you snag an SR-71 replacement. You want a low angle antenna for aircraft DX, not a high angle. On another note, I used to routinely talk with an aircraft with good signals out to 200mi with a 5w manpack transceiver with rubber duck antenna. If you’re in the clear, 1w works fine. Surprisingly, the same radio into a large antenna did not increase the range, it was only more solid until the inevitable fade out.
prcguy
kb2vxa said:
Hi J and all,

"1) Enable me hear the Atlanta tower (10 miles) and Atlanta Center (I believe at a different location that transmitts 20 miles away in Hampton, GA)."

Highly unlikely, that 10W into a groundplane or discone isn't meant to be heard by other than aircraft. The power and the antenna's vertical takeoff angle are designed solely for that purpose, not to hug the horizon over any particular distance.

"2) I would love to be able to hear high altitude aircraft from much further away than 90 miles."

So would I but again that's not the purpose, VHF is only meant to be heard within the operational footprint of the tower. They use HF for long distance comms.

"How much of this can I accomplish with a hand held antenna?"

Very little.

"Would a rooftop make a substantial difference in hearing the tower or distant high altitude aircraft?"

Possibly but there is no guarantee. It all depends on the antenna design, a high gain antenna hugs the ground and would defeat your purpose of receiving the aircraft but possibly pick up the tower but again there is no guarantee, especially at the range you stated. One thing for sure, a groundplane or discone like they use at the airport vs. an indoor antenna and especially a duck would make a definate improvement at least with the aircraft.

"Sounds like picking up aircraft with an attic or roof antenna should be pretty simple!"

Not as simple as it sounds, a crane would work better and there is less possibility of damaging the antenna. (;->)
 
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