so where are they????

Status
Not open for further replies.

Navairboss

Member
Joined
Dec 19, 2002
Messages
68
azraphale said:
Get a decent antenna and get it as high up as you can. If you wanna do mostly milair, get yourself a quality milair discone and mount it high, with the best quality coax you can get (and the shortest run!), would be my recommendation (for a single omni antenna that can cover the full milair band with fairly even gain throughout).
You have made my morning cup of coffee. So it is time to open up the mil antenna talk shop.

LOL, omni antennas with gain -- not gonna happen!! This myth has been pushed for years by manufacturers who wanted to make their omni antennas sound better on paper than the competition. A rubber duck antenna is a good antenna compared to the non-real antenna, but it is three db short of a dead short in my book.

In order to have true antenna gain you MUST have a directional antenna. I can make an omni appear to have gain over a theoretical antenna that doesn't exist or if I mount it on the side of a metal pole (creates directionality and thus gain). But with that scenario the antenna loses its omni characteristics which is most desirable in the milair world.

As for coax, there is also a point of diminishing returns. You can buy the most expensive coax in the world, and add the greatest preamp in the world, but if the scanner has a noise floor higher than what the coax and preamps provide, you have flushed it all down the drain.

Sorta like I need more receive signal and it is already full quieting on the receive end.
Hard line and other coaxes are a bear to work with, expensive (including connectors), and in "most" installations bring nothing more to the table.

If you are using an off the shelf consumer scanner for milair, then a nice omni or discone of your choice mounted clear of obstacles, some RG-6, and in some instances, a good low noise preamp may bring something to the table. But running out here spending big bucks on 9913, high dollar omni antennas and putting them at 50-100 feet into a Uniden BR-330 or some such, you have more money than sense and I could use some of your money. ;-)))

Now if we are talking milsats, totally different discussion. But that will be left for another day and another venue.

73 de Chief
 

Deepsky

Member
Joined
Jan 5, 2007
Messages
85
Location
Reno, NV.
I live in Reno and pick up flights to and from Beale and travis all the time from just the Artcc system. The trick is learning to understand what you hear. I just made my 88th milair hit two days ago and it was nothing more than a tanker moving into an AR route, It was real quick with little chatter some where over Oregon. Only once have I actualy heard an air 2 air conversation. Hell I went almost six months without a single milair hit when I first started and now I hear atleast two a week. Just don't give up and listen to the guys here because they helped me alot!
 

azraphale

Member
Joined
Aug 15, 2007
Messages
49
Location
Marlboro, NY
Navairboss, I suggest you go get some ham radio publications on antennas. There are plenty of omni designs that have gain over a 1/2 wave whip with ground plane, which is the standard 0 db gain reference. A good single-band discone (and "single-band" for a discone means a bandwidth of about 3x) should have about 3 db of gain over a 1/2 wave whip, which means double the actual signal level. Note as well that not all discones are created equal, and that you can build a good milair discone yourself for about $20 in parts from a hardware store and an hour or so of your spare time.

Of course a good directional antenna is going to be able to get better gain. You can get more than 12 db of gain with a good Yagi, but the better the gain, the narrower the badwidth; you'd need an awful lot of Yagis to cover milair with anything close to 12 db of gain, and then you'd need to point them at the traffic you wanted to receive.

A log periodic is a pretty decent compromise, especially if you get traffic predominantly from perhaps a 90 degree wedge of the compass; they are not as directional as Yagis, and cover a lot more bandwidth (they are in essence a series of differently-tuned dipoles spaced to enhance their gain). I've been seriously considering putting up several log periodics with different orientations to get good directional coverage plus gain, and I am researching the best way to design and build an LP at this point.

Quality coax is worth quite a bit in terms of signal, especially as frequency increases. A 50' cable run can lose up to 12 db of signal at 1 GHz when comparing the least lossy cable with cheap RG-6, and close to 6 db at 400 MHz. That's a lot of signal loss, so getting quality coax is important. The shorter the cable run, of course, the less loss. And it's far better to install a crimp-on connector on the end rather than using an adapter, if you can, as an adapter can lose you between 1 and 3 db by itself, especially at higher frequencies...
 
Status
Not open for further replies.
Top