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Author Topic: Airband Yagi antenna designs  (Read 67924 times)
vicosh
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« Reply #25 on: December 19, 2008, 04:41:53 AM »

Ok, understood! But I wasn't referring at the reception quality. I just wanted to know how the antenna will react at a lightning strke. A lightning strike.. this is the worst case. But in stormy/snow conditions the antenna could be loaded with some statical charge that could be discharged into the receiver. Does this antenna have any system to 'route' the statical charge to the earth?
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Biff
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« Reply #26 on: December 19, 2008, 09:25:50 AM »

You're still going to run your coax through a grounding block, right?

Ground the mast and the coax, and you'll probably be ok. 
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T210 Driver
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« Reply #27 on: December 24, 2008, 08:12:44 AM »

You can use a lightning protection system by grounding the antenna mount. 

But from experience ( I have 114 antenna sites operational), no matter what sort of of lightning protection you have, it will not prevent a lightning strike. 

If its your time....its your time.   shocked
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« Reply #28 on: January 24, 2009, 02:14:02 PM »

Here are some photos of the Airband Yagi antenna. The elements were made from copper tubing which were soldered with a short length of brass tubing since the copper tubes were sold in 3' lengths. The boom was made from wood, the box was a project enclosure from Radio Shack. Chassis mount Coax F connector, epoxy, heat shrink tubing, screw protectors on the element tips, and paint completed the project.
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« Reply #29 on: January 24, 2009, 03:10:30 PM »

Awesome construction job!
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dorough
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« Reply #30 on: July 15, 2009, 03:50:36 PM »

Would it be a good idea to use 1/4" threaded rod for the elements?
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dave
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« Reply #31 on: July 16, 2009, 10:39:44 PM »

Would it be a good idea to use 1/4" threaded rod for the elements?

Should be OK.
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spielberg
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« Reply #32 on: July 17, 2009, 04:23:11 PM »

I've just finished this antenna and it works like magic! I've had an own built discone antenna and I should say that this Yagi works so much better! The only problem I can see is that Yagi is a directional antenna and you need to spin it around to find the best position for every frequency, depending on the direction of the airport and transmitters, while a discone antenna works in all directions. But I can live with that. Thanks for posting this antenna idea, guys.
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FlyGuyAlex
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« Reply #33 on: September 27, 2009, 08:25:28 PM »

I also just made this.. Works fine but is still not what im looking for.
Im trying to pick up a ground station about 40mi. anything that can do that?

Thankss
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« Reply #34 on: September 27, 2009, 08:29:39 PM »

I also just made this.. Works fine but is still not what im looking for.
Im trying to pick up a ground station about 40mi. anything that can do that?

Thankss

The only thing that will help in this case is elevation.  smiley  But it depends somewhat on the ground elevation at each end of the path.  Are both ends around sea level?
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FlyGuyAlex
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« Reply #35 on: September 28, 2009, 06:32:53 AM »

The ground stations are up high in mountains.. and im at sealevel but on the roof so about 20ft AGL
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« Reply #36 on: September 28, 2009, 03:35:52 PM »

The ground stations are up high in mountains.. and im at sealevel but on the roof so about 20ft AGL

It also depends on what the remote station's antenna pattern looks like - and how much transmitter power they use.  Another factor is local noise at the receiving end (your end).  In that environment there can frequently be power line noise due to salt water and other corrosion effects.
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FlyGuyAlex
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« Reply #37 on: September 29, 2009, 03:20:46 PM »

Dave,

We have much noise on my antenna inputs because of radio stations. Our powerlines are burried in the ground so i dont think that can be a problem. I'm using a bandpass filter to get out the radio stations. Anything other i can do?
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« Reply #38 on: September 29, 2009, 03:57:41 PM »

Radio stations: AM or FM?
How far are the offending transmitters?
Multiple all in one location or just one?
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propwash
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« Reply #39 on: November 28, 2009, 05:54:28 AM »

Wow!  Thanks for getting me motivated to build something very similar based on those plans.

Unfortunately, the beam is currently indoors, so I run boom-less just hanging the elements from the rafters and letting gravity keep the wires straight.

I am also using an unconventional driven-element dipole, which consists of a quarter-wave wire attached to the center conductor of the coax feedline, and for the other side of the dipole, I use 4 ferrites (Radio Shack 273-105) snap-ons a quarter wave AND at a half-wave point down from the feedpoint.  This way I'm forcing the common-mode of the braid serve as the other half of the dipole.  The feedline serves as part of the bottom half of the dipole and the feedline itself.

(Normally instead of using a coil of coax for a choke, I like to use 4 of the type-43 ferrites right at the feedpoint, but in this case, I purposely move it down a quarter wave to emulate a wire.  Makes an interesting alternative to a j-pole driven element)

I'm still playing with the reflector spacing since I'm using 75 ohm coax, and hope to switch to 50 ohm soon.  But for now, the results are good, so thanks for publishing those specs!!

This is the first beam I've built, and now you've got me hooked!  Must make one for real outdoor use however... Smiley


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dan9125
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« Reply #40 on: December 16, 2009, 09:47:00 PM »

I have a question about the homemade Airband Yagi antenna antenna that Dave built. The plans call for the reflector element to be 48" long. Is that 48" total or is it 48" on each side of the boom?  The plans are not very clear on that.
  Thanks in advance, Dan
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dave
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« Reply #41 on: December 16, 2009, 11:12:16 PM »

That is total element length.  Divide the driven element length in half to get the length of each of the two element halves.
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dan9125
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« Reply #42 on: December 17, 2009, 08:31:15 AM »

Thanks Dave, thats what i thought but wanted to make sure. Hope to have one attached to the KBUF feed soon.
   Dan
 
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dan9125
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« Reply #43 on: December 28, 2009, 09:21:33 PM »

Finished my airband yagi today, hoping it improves reception. I wont be putting up for a week or two as its 19 degrees F and 30 mph winds in Buffalo. I used an old VHF TV antenna, moved and trimmed a few elements to spec. Had some 50 ohm Belden 9913 laying around so this hasn't cost me anything yet. Here is a pic.
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« Reply #44 on: December 28, 2009, 09:28:09 PM »

Strong work!  Hope it works well once you get it installed!
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saurabhchan
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« Reply #45 on: July 15, 2010, 04:21:28 AM »

Hi Dave,
I tried downloading the Pdf file but it says that it is corrupted file....can u help.
I am trying to build a yagi antenna based on that design

Thanks
Saurabh Chandra
These designs are reprinted with the permission of Kent England WA5VJB.  They appeared in the March 2008 issue of Popular Communications.

For those of you looking to get good airband reception in a particular direction, these antennas should work wonders for you.  And they are very inexpensive to build.

Enjoy - and you can find more designs and info at http://www.wa5vjb.com (currently in the process of changing DNS so try tomorrow).

-Dave


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Caleb
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« Reply #46 on: July 15, 2010, 03:35:57 PM »

One of my friends makes Yagi's. He currently has the desighn for military air, but VHF will be out soon. He has picked up (DX'ed) ground stations from over 175 miles away. They have a 9.8db gain. Scroll down to watch the video. This guy has the best milair setup I have ever seen. He is the best milair antenna maker by far.

Also, if you live in a less populated area, you may want to try a preamp. This is the same company that makes it for NASA www.AngleLinear.com

Yagi's are great for ATC, and air. They will do the BEST job.

73s
Caleb
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« Reply #47 on: November 17, 2010, 02:33:32 AM »

Is anyone interested in a 10 element yagi or log periodic antenna for the VHF air band?  I've been experimenting with some java number crunching programs, and worked out data for two such high gain antennas.  If you're interested in a particular airport or ATC sector that is hard to receive, one of these antennas could improve reception.

Here's the link: http://www.ab9il.net/aviation/airband-antenna1.html

The idea for an air band project came after enjoying good results with similar wi fi and FM broadcast antennas; 10 elements is about as large as practical for the aviation band.  Beyond that it makes more sense to just locate a receiver closer to the action.

Regards,
Phil
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MSLP
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« Reply #48 on: February 02, 2016, 10:39:41 AM »

what is the best antenna for good reception these of air signal
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InterpreDemon
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« Reply #49 on: February 02, 2016, 01:01:20 PM »

It depends upon many factors... what portions of the band you need to listen to, distance from ground stations or airports, elevation of your site above ground level, etc., not to mention space, mounting requirements, lightning protection and cost. For example, the antennas described in the prior few posts (5 yrs old) are about 12' long, need a decent and strong mounting and, unless you are pointing at a single station or airport within the radio horizon and far away, or you are surrounded by powerful radio and TV stations and need to point a pencil thin beam at a nearby airport in order to hear low power walkie-talkies or airplane tugs on the ground without interference, you would need an antenna rotator in order to listen to anything from other directions. On the other hand, if you are located far from any airports or ground stations with no hope of ever picking up any ground traffic, a simple ground plane antenna made from five pieces of #12 solid copper wire, an SO-239 or "N" bulkhead adapter and a couple feet of 1" PVC pipe will pick up just about anything in the air out to a few hundred miles depending upon how high they are flying.

Best would be to describe your situation and needs, then folks here can chime in with recommendations.
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