Antenna for MilAir in the attic suggestions?

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whooey

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I am going to dedicate my 996T for MilAir. (225-400) I am going to run a Antenna in the attic. What would be my best choice for mounting a Antenna in my attic tuned for MilAir, also which cable would you run?
If I had to guess I would say the mounted antenna in the attic would be 15-17 feet off the ground. Better than a ducky!

Thanks for your input!
 

specman

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whooey said:
I am going to dedicate my 996T for MilAir. (225-400) I am going to run a Antenna in the attic. What would be my best choice for mounting a Antenna in my attic tuned for MilAir, also which cable would you run?
If I had to guess I would say the mounted antenna in the attic would be 15-17 feet off the ground. Better than a ducky!

Thanks for your input!
I would personally recommend a J-pole cut to the right size; can be made with TV twin-lead and housed in plastic pipe. Hang from roof supports. You can use good quality RG-6 coax for the cable run and keep the costs down. Good luck!
 

K6PCW

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Another vote for the J-pole. I had one custom-cut to 300Mhz, which is smack-dab in the middle of the UHF milair band. J-poles are not wide-band antennas, but since you're not transmitting, the trade-off shouldn't be a big issue. The price is right, too. Between $20 and $40, depending on your source. You'll pay more for a custom-cut antenna. Mine was $30 or so. I can't remember exactly...

By the way, why dedicate the 996 (digital) to strictly milair (analog)? Why not dedicate a less-expensive analog scanner (215?) for milair and utilize the 996 for other stuff?
 

whooey

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k6pcw said:
By the way, why dedicate the 996 (digital) to strictly milair (analog)? Why not dedicate a less-expensive analog scanner (215?) for milair and utilize the 996 for other stuff?
B/c I have my 396T/Pro96/Pro2096 x 2 on the digital stuff. :)
 

K6PCW

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For whatever it's worth...

Although I have no personal knowledge or opinion of this product, a review of such a product is posted on this site:
http://www.milaircomms.com/

Perhaps others here will be more knowledgeable about the products offered. I'd be interested, too!
 
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prcguy

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I was going to say this antenna would be a great buy up to about $75, but it looks like it will go higher. See Ebay item # 120043622816. This is one of the best military Discones made specifically for the 225-400MHz band. Makes your mil-air listening happy happy. A J-pole is fairly narrow band and performance will degrade sharply away from it’s design freq. A bunch of folks have range tested J-poles and found a simple 1/4 wave ground plane will usually equal or slightly outperform it.
prcguy
 

specman

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prcguy said:
A J-pole is fairly narrow band and performance will degrade sharply away from it’s design freq. A bunch of folks have range tested J-poles and found a simple 1/4 wave ground plane will usually equal or slightly outperform it.
That's pretty subjective. Let's consider a few items here:

1. The frequencies of interest are sufficiently narrow for any monoband antenna to work with
2. We might have a restricted amount of space to work with (attic).

The J-pole suits these requirements nicely; no need for radials either. I've made quite a few and have found situations where they outperform the equivalent marconi (and the other way around). For this application the difference in radiation angle might work out a bit better. Every situation has a solution, vanilla is not always the answer.

In any case, it appears the original poster is favouring something directional for his needs.
 

iMONITOR

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k6pcw said:
Although I have no personal knowledge or opinion of this product, a review of such a product is posted on this site:
http://www.milaircomms.com/

Perhaps others here will be more knowledgeable about the products offered. I'd be interested, too!
That review is old, and obsolete, on a discontinued model. I personally have used the Miltenna LP and it works great!
 

JackTV

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I use the mil air LPA from Dave at DPD productions.Great antenna for mil air and has good gain.Use some good coax and you should be very happy.Mine is outside about 35ft in the air with a RS rotator. Highly recomended and a good price.

Good luck,
Jack
 

whooey

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I have read some info on the LP from DPD. How directional is it? If I put it up in my attic I cant turn it and what not. I am leaning toward the LP, but if its super directional, I may have to go with a more omnidirectional antenna.

Thanks for your help BTW guys.
 

DPD1

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It's not super directional like a yagi... It's basically like having a normal omni, but with added gain in one direction. A Yagi uses parasitic elements to achieve directional properties, where as the LP design uses "driven" elements. So the LP is much more responsive in omni. Plus, when you've got 10 driven elements all working for you in just one band, it's more like the gain of a yagi.

But... In an attic, the problem is you're getting a lot of reflected signals. The true directional ability might be masked a bit. If you plan on going outside eventually, the LP would be good. But if staying in the attic is your goal, I'd pick the Omni. Most people like the UHF/VHF model. Even if you aren't that interested in VHF, it's worth the few extra bucks. The VHF elements can be removed if you're tight for space, and the UHF portion will still perform the same.

Dave
http://www.dpdproductions.com
- Custom Scanner, Aviation, MURS, GMRS, Marine & Ham Antennas -
 

tonsoffun

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I can say that the DPD LP works just as well on all the local stuff as my discone. But if I want a specific tower site that is farther then the local sites and turn the the LP to the tower it comes in 2 to 3 bars better then the discone. Again it all depends on your situation.
Take care
 
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prcguy

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The mil-air frequencies of interest span 225 to 400MHz and a J-pole will work great at maybe 10MHz BW @300MHz design center. After about 20MHz BW it will start to degrade and a Discone will easily outperform it. 20MHz BW is about 10% of the mil-air band, why would you say the J-pole suits these requirements nicely?
prcguy
specman said:
That's pretty subjective. Let's consider a few items here:

1. The frequencies of interest are sufficiently narrow for any monoband antenna to work with
2. We might have a restricted amount of space to work with (attic).

The J-pole suits these requirements nicely; no need for radials either. I've made quite a few and have found situations where they outperform the equivalent marconi (and the other way around). For this application the difference in radiation angle might work out a bit better. Every situation has a solution, vanilla is not always the answer.

In any case, it appears the original poster is favouring something directional for his needs.
 

prcguy

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Oops, forgot to ask if you tune your J-pole to the mil-air freqs? If you don’t actually tune it you will have additional losses. I’m not a fan of home made antenna projects for the masses if the masses can’t reproduce the design. There are a bunch of J-pole designs for amateur radio freqs that have detailed instructions for the matching section, but scaling the J-pole to other bands does not allow for the usual trial and error of optimizing the matching section. Most folks don't have the test equipment to do this and most "amateur" antenna analyzers don't cover the mil-air freqs.
prcguy
specman said:
That's pretty subjective. Let's consider a few items here:

1. The frequencies of interest are sufficiently narrow for any monoband antenna to work with
2. We might have a restricted amount of space to work with (attic).

The J-pole suits these requirements nicely; no need for radials either. I've made quite a few and have found situations where they outperform the equivalent marconi (and the other way around). For this application the difference in radiation angle might work out a bit better. Every situation has a solution, vanilla is not always the answer.

In any case, it appears the original poster is favouring something directional for his needs.
 
N

N_Jay

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prcguy said:
Oops, forgot to ask if you tune your J-pole to the mil-air freqs? If you don’t actually tune it you will have additional losses. I’m not a fan of home made antenna projects for the masses if the masses can’t reproduce the design. There are a bunch of J-pole designs for amateur radio freqs that have detailed instructions for the matching section, but scaling the J-pole to other bands does not allow for the usual trial and error of optimizing the matching section. Most folks don't have the test equipment to do this and most "amateur" antenna analyzers don't cover the mil-air freqs.
prcguy
Just make a vertical dipole tuned to the center, and feed it with RG-6.
 

specman

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prcguy said:
The mil-air frequencies of interest span 225 to 400MHz and a J-pole will work great at maybe 10MHz BW @300MHz design center. After about 20MHz BW it will start to degrade and a Discone will easily outperform it. 20MHz BW is about 10% of the mil-air band, why would you say the J-pole suits these requirements nicely?
prcguy
Fair enough questions; I'll answer those but this will be my last post in this thread since it's diverging from the original question (I'll gladly continue to discuss it elsewhere though).

I won't disagree that a discone will outperform the J-Pole over the range of frequencies, but we were never debating about discones before. I'd also remind you that the mil-air portion really only extends to 380 MHz now.. although there's other items now to listen to above that for some people.

The reason I like J-Poles for some situations is that they are great "problem solver" antennas. Compact (at least at these frequencies), durable (the way I make them) easy to mount (I hang them) and no special considerations for ground plane required. Are they the best all round Mil-Air (or any band) antenna? Certainly not... but you have not once addressed the other part of what I was talking about - confined space. I had assumed the original poster was placing this in an attic.. perhaps with limited space to work with. If he has space for a discone or the specialized model shown above, then yes I would agree he should go for something else.

I have made at least one model for mil-air; in the case I recall I had made it along with another for VHF and used them in a temp situation (a dorm I was staying in for several months) and they worked very well for what I needed. I did not experience any sharp decrease in peformance on any frequencies I monitored, but to be fair most of them were likely near the center of my design anyways. I don't want to give the impression that J-Poles will solve all the worlds antenna woes; they are only one possibility for some situations, other situations will dictate other solutions.

You had also mentioned a comment about homebuilding of antennas; agreed it is not for everyone.. but I've found that it is a particularly rewarding aspect of the hobby. Luckilly enough there's resources for both those who prefer to buy something premade and those who like to tinker.

Cheers :)
 
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DPD1

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When analyzing a J design in the 225-400, you are going to see a better match than you would in VHF, because finding a good match gets easier as you get higher in frequency. The bandwidth automatically goes up as well. But typically you are still going to get a width of maybe 15-20 MHz out to 1.5, and after that it just keeps getting worse. For receive purposes, out to 3.0 isn't going to be a significant difference to the ear. But it gets a lot worse than that... Pretty much off the scale eventually. My equipment goes off the scale at about 1:6, and it does that for a significant portion of the band in that design. Does that mean you won't hear anything in the bad part? No not at all. In fact, you will probably hear a boost over unity in the 20-40 MHz portion in the middle... But you will also hear a degradation on the outer portions of that. The only way possibly around that, would be to create a fat design.

As far as home designs go... Yes, it's true that there is a misconception that simply building something to a specific physical dimension, will guarantee resonance and other factors to be where they need to be. It won't. Materials and dimensions can change things radically, and even installation can change things. Which is why professional level transmission systems really need to be installed and tuned on a system by system basis.

I keep hearing they're switching the 380-400 to land systems only, but I still hear SQ tacs and other stuff on those.

Dave
http://www.dpdproductions.com
- Custom Scanner, Aviation, MURS, GMRS, Marine & Ham Antennas -
 
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