two antenna setup

[a.steggall]

Would there be any problem with this setup. One feedline from the duplexer up to a T-connecter out from the T-connecter with two feedlines and in to one low gain (2.5 dbi) and one high gain (7.5 dbi) antennas. about 10 ft. apart.

The problem im having is the high gain antenna tends to over shout some area close to the site. The low gain antenna tends to not get some of the long range.

[Jonathan KC8RYW]

I suspect it might be easier if you use one feedline. Put the T at the end of the run, right between the two antennas, and use jumpers between the two. The values and type of jumpers will be critical.

But I'm just a ham, so take what I say lightly until an RF expert replies. I'm just curious to see if I was even close.

[Jim202]

[quote="a.steggall"]Would there be any problem with this setup. One feedline from the duplexer up to a T-connecter out from the T-connecter with two feedlines and in to one low gain (2.5 dbi) and one high gain (7.5 dbi) antennas. about 10 ft. apart.

The problem im having is the high gain antenna tends to over shout some area close to the site. The low gain antenna tends to not get some of the long range.[/quote]


It would help some if you gave just a little more info.

Like how high up on the tower are these two antennas?

What is the elevation of the site?

What is the elevation of the areas that your having close in problemswith?

What is the elevation of the distant areas your trying to work from?

What type of terrain is the area of concern. Flat, rolling hills, large up and downs, mountains?

Jim

[JohnWayne]

The first problem is that your antenna setup is a complex RF network, NOT a simple DC network. This means that when you put your T adapter in there it is going to change the impedance of the network quite a bit. It is possible to make a phasing harness if you know what you are doing.

What you are trying to do is make a phased array like the CB'ers use on their vehicles. It doesn't really do anything except look goofy, and your setup would have similar results.

I think the real problem is that you are trying to throw the wrong solution at this problem. As Jim said, let's get some more info on your setup. Why are you using two antennas in the first place even?

Jeff

[DBoeing]

Talk to an engineer at Celwave or what ever antenna brand you like and be prepared to give them the tower details height power out size of coax distance you are tying to cover type of terain. Most likely you need a high gain antenna with down tilt.

[a.steggall]

Thanks for the replys. This was just an idea I have. I guess I will just look in to a better one ant. setup then I have now.

[bernie]

My two bits worth:
All of the components in your antenna system are 50Z components.

(Z=impedence, opposition to alternating current)

The "T" connector must be a matching transformer.
I have used splitters made by Telwave, and Scala.

Considering losses and other problems, you may well find that the network will not perform as expected.

The antenna spacing is quite critical, because of phase cancellation.

I have worked with very few system in which antennas with matching systems performed better than one antenna.

Some applications for such systems is Hospitals, and Airports.

[a.steggall]

Fixed this problem. Got a better antenna a DB-408 and works alot better now.