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eHam Forums => Antennas and Towers and more => Topic started by: K4RVN on November 07, 2012, 02:33:43 PM



Title: Chain link fence as ground for beverage antenna
Post by: K4RVN on November 07, 2012, 02:33:43 PM
I have my wire in place for a 40 meter beverage antenna. I will be feeding it with 150 ft  RG6 and a transformer near a chain link fence about 100 ft long. I plan to install the transformer and a ground rod near the fence corner. Would it help to also connect the rod to the chain link corner post for a ground? The other end of the single wire beverage is in the woods about 350 ft away and will be terminated with a ground rod and 450 ohm resistor in a waterproof enclosure. Wire is 17 gage galvanized electric fence wire. Thanks for any comments on the corner post as a ground also.

Frank


Title: RE: Chain link fence as ground for beverage antenna
Post by: W0BTU on November 07, 2012, 08:01:04 PM
Try it both ways and see. You can use AM broadcast stations during the day as a constant signal source.

Here's some of my experiences with Beverage grounds. I'm a big fan of radials.
http://www.w0btu.com/Beverage_antennas.html#Beverage_antenna_grounds


Title: RE: Chain link fence as ground for beverage antenna
Post by: K4RVN on November 08, 2012, 04:47:41 PM
Thanks Mike, I'll try that.

Frank


Title: RE: Chain link fence as ground for beverage antenna
Post by: W5LZ on November 09, 2012, 12:21:12 PM
I think that "try it and see" is probably the best advice you'll get.  Using a chain-link fence as any part of an antenna is very -iffy-.  Most apparent problem is just how much of all that 'wire' is making adequate contact with the next piece of that 'wire'.  Something to keep in mind is that the fence does become part of the antenna.  If that fence happens to run next to your neighbor's (or your) electronics, it's like having your antenna that close to it.  That interference works in both directions you know.  Try it, see what happens and go from there.
 - Paul


Title: RE: Chain link fence as ground for beverage antenna
Post by: WB6BYU on November 09, 2012, 12:27:53 PM
The sections of a chain link fence don't always make good contact with each other,
so they aren't a reliable ground from that perspective.

The support posts don't go as deep as a typical ground rod, and often are encased
in concrete, which isn't as good of a conductor as dirt.  So if you are just thinking
of using a post in place of a ground rod, it likely won't work as well for that, either.


So "try it and see" isn't a bad approach.  Don't expect a lot from it, however.


Title: RE: Chain link fence as ground for beverage antenna
Post by: K4RVN on November 09, 2012, 07:28:55 PM
I tried it, picked up another ground rod today and will disconnect the fence and use the ground rod only tomorrow. The antenna seems to work OK with the fence as a ground, but I won't know until tomorrow when I use the ground rod.
I have an AM broadcast station about 1/2 mile from me. The station overloads my transceiver on 40 meters with the beverage in use  making it impossible to use in daytime and until the station signs off. My half square is fine no problem as I have an ice broadcast band filter on it. The beverage is pointing toward the station tower.  I may run another one for VK land and asia
sooner than planned. It has been fun and educational to learn about the beverage antenna. Thanks to all for the comments.

Frank


Title: RE: Chain link fence as ground for beverage antenna
Post by: W0BTU on November 09, 2012, 07:37:33 PM
I have an AM broadcast station about 1/2 mile from me. The station overloads my transceiver on 40 meters with the beverage in use  making it impossible to use in daytime and until the station signs off.

Even with the BCB filter?
Can you switch in an attenuator?


Title: RE: Chain link fence as ground for beverage antenna
Post by: K4RVN on November 09, 2012, 10:28:23 PM
Mike, the Beverage plugs in with a phono plug as I have it set up directly to the receiver aux input on the omni 6 plus. The 40 meter half square goes into my watt meter and into the transceiver through the bcb filter on the transceiver. I will have to install a switch which I have to feed through the bcb filter. I have two transceivers, but the 7200 Icom only has one ant input.
I have some work to do before I get it like I want it to work for me. I was on 40 late tonight and also tried the beverage on 80 and 160 bands. It really makes a difference in the signals on the s meter from stations it is pointed toward.

Frank


Title: RE: Chain link fence as ground for beverage antenna
Post by: K9FV on November 10, 2012, 05:07:22 PM
Frank, what is the results of ground rod vs chain link fence? 

I got my wire up today, hope to get a ground rod and transformer installed for a test Sunday night.... or Monday at latest.

73 de Ken H>


Title: RE: Chain link fence as ground for beverage antenna
Post by: K4RVN on November 10, 2012, 09:12:30 PM
Did not get to it today, had to attend a surprise birthday party for a friend. I 'll do it Monday and try it out Mon. night
if all goes well. I'm going by radio shack to get a F6 to pl 259 adaptor so I can connect it to my filter for broadcast
interference. I have receive overload in daytime due to an AM broadcast tower close by. The filter will eliminate the problem.

Frank


Title: RE: Chain link fence as ground for beverage antenna
Post by: W4VR on November 11, 2012, 09:10:44 AM
For what it's worth I use three 6-foot ground rods at each end of my beverage antenna.  The rods are spaced about 1.5 feet apart in a triangle.  I don't think it's a good idea to tap into a chain link fence...too many iffy connections throughout and could contribute more noise than w/o it.  


Title: RE: Chain link fence as ground for beverage antenna
Post by: K4RVN on November 11, 2012, 01:35:00 PM
Thanks for the reply. I will check it out tomorrow with one ground rod and the fence
disconnected. I drilled a hole in the post and used a stainless steel screw and washers to attach the wire. My fence posts are all in concrete and spaced 10 ft apart. The fence runs two directions, East and West for about 100 ft each direction. The wire has been up a long time and dirt is along the bottom of the fence. Wire is attached to top rail and fence posts with aluminum wire ties. Not too positive for conductivity but reads zero resistance to ground with ohm meter along the fence. I plan to leave the fence disconnected unless there is a loss of signal. Just fooling around here and trying things to see what happens.

Frank


Title: RE: Chain link fence as ground for beverage antenna
Post by: K4RVN on November 12, 2012, 02:59:41 PM
You are right W4VR. The Broadcast band noise was less when I disconnected the fence as I believe the fence was rectifying some parasitics perhaps. Anyway I left the fence disconnected, only one ground rod driven in about 6 ft. The antenna can now be used in the daytime as it is much quieter. Lowes has an 8ft copper coated ground rod for less than 12 bucks. Appears 5 to 6 bucks cheaper than the same one at Tractor supply. I'll pick up another this week and try two on the transformer end. I'm through with this antenna build
for now. Now is the time to use it to see how it does on Europe. I'm also going to do some broadcast listening on my Lafayette HE10.

Frank


Title: RE: Chain link fence as ground for beverage antenna
Post by: W0BTU on November 12, 2012, 03:08:16 PM
I suggest you think about adding some 50' radials. They might very well be more effective than ground rods. That's certainly been my experience: http://www.w0btu.com/Beverage_antennas.html#Beverage_antenna_grounds

Just staple them to the surface of the ground with lawn staples, or pieces of plastic-coated steel clothesline bent into a U. They will disappear into the grass in a few months. No need to bury them.  Here's proof that radials (even short ones) work better than ground rods: http://www.w8ji.com/ground_resistance_measurements.htm


Title: RE: Chain link fence as ground for beverage antenna
Post by: K4RVN on November 12, 2012, 08:01:54 PM
Mike,
I'll do that as I have the wire etc. Tried the antenna tonight listening on 160 and 80 meters. It really makes a difference in noise and signal strength from staions in the North.
I have plenty of room for the radials and no HOA, or wife problems after over 50 years together with my antennas.

Frank


Title: RE: Chain link fence as ground for beverage antenna
Post by: K4SAV on November 13, 2012, 07:18:29 AM
A Beverage doesn't require a very low impedance ground connection.  A single ground rod should do.  If the ground rod has more impedance than you like, just subtract a little from the termination resistor value.  You can determine if the load impedance is correct by measuring the SWR at the input to the Beverage. 

Jerry, K4SAV


Title: RE: Chain link fence as ground for beverage antenna
Post by: W0BTU on November 13, 2012, 11:41:06 PM
A good Beverage ground may not be as important as some other antennas, but that doesn't mean the ground resistance is inconsequential. A poor ground on a Beverage can make the signal levels and F/B ratio suffer, especially on a 2-wire bi-directional Beverage.


Title: RE: Chain link fence as ground for beverage antenna
Post by: WB3BEL on November 14, 2012, 07:03:47 AM
What Jerry is saying is that having a low ground resistance on the order of 10s of ohms will not materially change the system termination resistance which is in hundreds of ohms.  This is very true.  So the antenna pattern will not be influenced in any significant way even if you only have a poor ground on the Beverage.

I think why some folks think a good ground is needed for Beverage has more to do with common mode problems than termination impedance.  This is a very important issue and if you live where it is very noisy, you should take care to provide adequate choking impedance to avoid common mode pickup.  This obviously is more important on the coaxial feedpoint side of the Beverage.  It is often not enough to rely on the Beverage transformer for common mode suppression.  Attention to the grounding at the transformer and use of multi-turn coaxial choke through large ferrite core at both ends of the feedline may make a difference in noise or interference pickup.

These common mode practices are even more critical for small receiving antennas like flags and pennants.