Using a 102 whip as a base station

[Turbo T]

I've heard people in the past using 102 whips as base station antennas, and they did it by having a ground plane made up of horizontal wires on 4 sides under the antenna.

1. If I go this route can I use copper wire as the ground plane? Or does it have to be steel of some sorts?

2. Since the 102 is nearly 9 ft tall, do the horizontally wires under each side of the antenna need to also be the same length of the antenna? Or could I just make a cross out of two pieces of 9 ft wire so as each length of wire on any side under the antenna was roughly 4.5 feet?

Thanks in advance.

 

[Robb]

I've heard people in the past using 102 whips as base station antennas, and they did it by having a ground plane made up of horizontal wires on 4 sides under the antenna.

Yup.

1. If I go this route can I use copper wire as the ground plane? Or does it have to be steel of some sorts?

Steel, aluminum, or copper is OK.

2. Since the 102 is nearly 9 ft tall, do the horizontally wires under each side of the antenna need to also be the same length of the antenna? Or could I just make a cross out of two pieces of 9 ft wire so as each length of wire on any side under the antenna was roughly 4.5 feet?

Same length as the 1/4 wave vertical/each radial.

Thanks in advance.

Enjoy.

 

[Turbo T]

Same length as the 1/4 wave vertical/each radial.

Thanx rob, that's gonna be a pretty darn big around radial.

 

[15minigrass]

 

[Robb]

You can use one radial - as minigrass showed in the pictures above. It will skew the radiation pattern (gets 'lop sided') if you want to use less than four. But it will work.

Please note that the radial is at a downward slope from the center radiator. Lowering the radial(s) from being level can be used to tune the SWR for optimal reflection. Usually, a 30 to 45 degree downward slope of the radial(s) is where you will find the best SWR.

 

[Marconi]

I've heard people in the past using 102 whips as base station antennas, and they did it by having a ground plane made up of horizontal wires on 4 sides under the antenna.

1. If I go this route can I use copper wire as the ground plane? Or does it have to be steel of some sorts?

2. Since the 102 is nearly 9 ft tall, do the horizontally wires under each side of the antenna need to also be the same length of the antenna? Or could I just make a cross out of two pieces of 9 ft wire so as each length of wire on any side under the antenna was roughly 4.5 feet?

Thanks in advance.

Turbo T, you can use copper wire, but supporting the wire can be an issue. You can also use conduit, copper, or aluminum, but to some degree the diameter of the material will control the resonance, albeit this antenna should show a very wide bandwidth. The problem with using horizontal radials on a 1/4 wavelength radiator is the match will not be very good showing very low resistance and a high SWR. If you angle the radials down to 40* degrees or less you will get a much better match.

Here is a model of the idea you have in mind. The pattern is not too bad, but check out the last page, the "Source Data" and you will see the resistance will likely be very close to 18 ohms at the feed point, showing about 2.8:1 SWR and that is not too good. This model is at 32' feet high with a mast attached, and if you change the height the match will also change a bit.

View attachment .25 wave horizontal radials 108''.pdf

 

[W5LZ]

Those radial(s) can be anything conductive. As has been said, wire will work fine but you have to support it in some way. Big? Well, no bigger than any other 1/4 wave 11 meter groundplane type antenna. How long? Somewhere between 8 1/2 feet to 9 feet long give or take a couple of inches. Basically, the same length as the vertical element. Or, mount that vertical part a foot or so off the ground and lay the radials on the ground, it works. You'll have to tune the thing no matter how high it is.
- 'Doc

 

[Turbo T]

Hhhmmm wonder if it would be easier to buy a radial as opposed to building one?

I have a buddy of mine I'm actually thinking of just giving him the 102 and letting him run with it. He needs something better for his base station than a home made dipole.

 

[W5LZ]

You know, if your friend made that dipole half way right, and if he hung it vertically, there wouldn't be a nickle's worth of difference between it and that whip with a few radials. Take another look at that single radial antenna a couple of posts up. It's a vertically 'hung'/mounted dipole.
- 'Doc

 

[Marconi]

You know, if your friend made that dipole half way right, and if he hung it vertically, there wouldn't be a nickle's worth of difference between it and that whip with a few radials. Take another look at that single radial antenna a couple of posts up. It's a vertically 'hung'/mounted dipole.
- 'Doc

Let's see what Eznec5 says regarding 'Doc's claim that there is less that a $.05 difference as described. It might be true if you believe that construction has little to nothing to do with performance of a vertical antenna.

I used a model I had of a .25 wave radiator at 12' feet high, with 4 horizontal 108" radials. I then slanted the radials down at less than 40* degrees and made the model resonant. I then removed 3 of the 4 radials and made the model look similar to what 15minigrass shows which is the bases of what 'Doc tells us.

I can't make a claim here either way, but this is what Eznec5 shows me.

View attachment .25 wave for 'Doc issue on 070311.pdf

 

[mackmobile43]

You can take that same 102'' whip and suspend it in mid air with string or rope and have the radial wires attached and then tie string or rope on the ends(string or rope needs to be non conductive) and pull them at a 45` angle or so and you have your 1/4 wave vertical.

Keep in mind you have no electrical connection to earth other than your coax's shielding so close consideration to safety should be taken when electrical storms approach.

 

[Riverman]

I hate asking silly questions, but am forced to for a while as I am just now getting back into radios. I've forgotten everything I once knew. Here goes . . .

If the vertical and radial are both 1/4 wave in length, what determines if an antenna (like the one in the photos) is a ground wave or a dipole?

 

[Marconi]

I think it looks like a bent dipole to me and if you move the feed point around to different configurations you might improve the pattern, angle, and gain noticeably.

 

[Riverman]

Still a little confused. I'm told a ground plane can be made with only one radial (performance suffers), but what exactly makes it different from a dipole that isn't completely vertical? Is it because on a dipole, the bottom radial is insulated from the steel mast where as on a GP it isn't?

 

[nosepc]

I hate asking silly questions, but am forced to for a while as I am just now getting back into radios. I've forgotten everything I once knew. Here goes . . .

If the vertical and radial are both 1/4 wave in length, what determines if an antenna (like the one in the photos) is a ground wave or a dipole?

Is a L shaped dipole.

nice! over real ground I drawing this models

at 18'





at 36'...