D*STAR dual band attic for HT
I have an Icom 92AD (D*STAR enabled) and would like to put an antenna up in the attic (I'm not ready to start dealing with lightning protection and the like). The nearest D*Star repeaters are quite far away so I would like to optimize for distance, keeping in mind that the HTs are limited in power (more of a challenge - that's always a bonus).
I probably have a good 3-4' to work in, and a very large attic space (1400 sq ft ranch) with nothing but insulation so I have plenty of room to work in.
What types of antennas should I be looking at in a case like this?
If you switch from analog to digital radio you have to buy a new digital antenna.
I think the nearest D* system is in Chicago !
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Originally Posted by K8JD
A 2m or 440 beam should fit in that space just perfectly, are You trying
to get into W8LIV, or another one?
Have you tried 145.670 simplex DV mode?
Height of antenna is paramount in VHF/UHF communications. The general rule of thumb is 2 times the square root of the height of the antenna. Take the following situation:
You have 2 stations that wish to communicate via simplex. The distance between them is 50 miles. There are several ways to make this happen. All the following assumes there are no obstructions between the 2 stations.
Solution one: Both station antennas need to be about 200 feet ASL. This will make the radius of communication for both stations about 28 miles. The overlapping radii will allow reliable communication between each station.
Solution two: One station would have to have an antenna at 325 feet ASL. The radius of communication for that station is about 36 miles. The second station would need to have its antenna at about 100 feet ASL (20 mile radius) to complete the path, allowing for some overlap.
If you know the height of the repeater's antenna, you can figure out how high your antenna needs to be to hit it. If the repeater antenna is 75 miles away, and is at 900 feet ASL, you need to have your antenna at about 100 feet ASL (with no intervening obstructions) to make it into the repeater reliably.
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I would make a simple 1/4 wave vertical like: http://www.bloomington.in.us/~wh2t/Jpole.htm and see if that meets your needs.
Be sure to listen for my beacon on 28.278.8 MHz
When I use the Splat software, that seems to be the case, but in reality,
there are many more variables.
Gain antennas, aircraft reflections, backscatter, reflections, knife-edging
off the tops of tall buildings, parasitic re-radiation from metallic structures
along the communication path, these can all help or degrade signal along
Let's not forget temperature inversions. Big business in this area.