Multiple Antennas and Multiple Radios

[thinbluebbq]

Hello, all. I currently have an HF Wire and an HF vertical antenna at my QTH. I have two HF radios and soon to be a third. I will be stringing up a second wire antenna between the trees. Two questions for the experts in the group.

1. Is there any way to feed multiple radios with one antenna without having to constantly unscrew and switch antennas at the back of the radios? Can I use an antenna switch in reverse?
2. I have two large trees on my property allowing me to put up two wire antennas. I will have one at about 50' up in an inverted L and the other would be an endfed up about 30-35'. Would there be any problem with one being over the other? Will it cause any reflection issues or anything?

Thanks in advance for the advice!

 

[KB4MSZ]

I suggest taking a look at these before using an antenna switch in reverse.

USING ANTENNA SWITCHES

I'm currently using a Dawia antenna switch in order to switch between two station setup's. Two transcivers, two amps, one swr/power meter, and one antenna (imax 2000.) Is it possible to switch between 2 transceivers, swr/power meter, and a single amp as opposed to two amplifiers by adding...

www.worldwidedx.com

Transceiver Coaxial Cable Selector Switch

If you are going to connect two or more transceivers to a single antenna using an antenna selector switch, be warned, you need to consider how much RF you are dumping into the unused transceiver. T…

swiradio.org

This one gets a bit more in-depth on the subject.

 

[mmckenna]

Patch panels are a good option. More capability than a switch. Use BNC connectors for easy changes.

If the wire antennas are parallel they can become directional. If they are crossing at a 90º angle, it's "more better".

 

[prcguy]

If HF antennas are close to each other they will interact changing the directional properties and you will have coupling between antennas. I would be careful with coupling and would measure it to see how much power is picked up by one antenna when transmitting on the other.

I damaged an expensive radio here once and I'm convinced it was antenna coupling that caused it. After the radio was repaired and I thought about how it was damaged I connected a wattmeter and load to the antenna on the damaged radio and measured about 10 watts of energy picked up when I ran my 1.2kW HF amp. That is enough power to damage a receiver.

The OP mentioned one antenna at 50ft and the other running under it at 30-35ft which is only 15 to 20ft of separation. That can be a lot of coupling at HF and should be measured to be safe.

 

[mmckenna]

The OP mentioned one antenna at 50ft and the other running under it at 30-35ft which is only 15 to 20ft of separation. That can be a lot of coupling at HF and should be measured to be safe.

What kind of orientation was that between the two antenna, or did it matter?

 

[prcguy]

I have an OCFD where the feedpoint is hanging about 2ft off the top side of a tower and I had an end fed trap 1/4 wave wire on 10, 20 and 40m sloping downward from the top of the tower and at a right angle to the OCFD. In general running HF wire antennas at a right angle to each other should minimize the pickup on most bands but a multiband will have lots of lobes on the higher bands that can couple more into another wire at a right angle.

What kind of orientation was that between the two antenna, or did it matter?

 

[mmckenna]

I have an OCFD where the feedpoint is hanging about 2ft off the top side of a tower and I had an end fed trap 1/4 wave wire on 10, 20 and 40m sloping downward from the top of the tower and at a right angle to the OCFD. In general running HF wire antennas at a right angle to each other should minimize the pickup on most bands but a multiband will have lots of lobes on the higher bands that can couple more into another wire at a right angle.

That makes a lot of sense. Thanks for the explanation.

 

[WA8ZTZ]

Patch panels are a good option. More capability than a switch. Use BNC connectors for easy changes.

IMHO, the patch panel thing is the least expensive and easiest way to go.
Just be careful to plainly layout and label everything so as not to end up
transmitting from one set into another.
Be sure to consider lightning protection.

 

[mmckenna]

IMHO, the patch panel thing is the least expensive and easiest way to go.
Just be careful to plainly layout and label everything so as not to end up
transmitting from one set into another.
Be sure to consider lightning protection.

Yes, absolutely
When I first got my ham ticket, I picked up a nice BNC patch panel at a swap meet. Made it super easy to swap antennas/radios and compare performance. I learned a lot from that. Not sure what happened to it, probably sold it off.

Wouldn't be hard to make one. Panel mount connectors are not expensive. Get a copper plate to mount them through and it gives you a good common ground point, also.

 

[thinbluebbq]

Patch panels are a good option. More capability than a switch. Use BNC connectors for easy changes.

If the wire antennas are parallel they can become directional. If they are crossing at a 90º angle, it's "more better".

Thanks. Are you advocating then for using the patch panel and just quickly switching antennas rather than having multiple antennas hooked to multiple radios at the same time? Somehow I need to try to have two radios online at the same time if possible.

 

[mmckenna]

Ideally you'd have two rows of connectors.

One row would have a connection for each of your antennas.
The other row would have a connection for each antenna input on your radios.

You'd have a set of patch cords. You'd just patch individual antennas to the individual antenna inputs. The beauty of a patch panel is makes it much easier to make changes. You don't have to pull the radio out and unscrew connections and reroute antenna cables. You'd just move the patch cord to whatever configuration you'd want.

If you used BNC connectors, it's much easier to make quick changes. BNC connectors will usually handle around 300 watts at up to 1GHz. Usually they are rated for up to something like 11GHz. If you need more power capability, use the appropriate connectors.