This is the story of how I constructed the ground mount for it.

First a related story…

The day after Christmas my son and I carefully replaced the current copper pipe 16 foot vertical with the pieces from the kit which includes a nifty tilt-base, 4:1 balun and lots of hardware. The details of the actual 43 foot antenna installation will be detailed in another post. For now, I am here to tell a story of how to accommodate the needs of the XYL.

While my son and I were assembling the antenna some 200 feet away from the house it appears the mother-in-law and my wife were not liking what they saw. The wild imagination expressed by by mother-in-law included statements like “It will take five people to carry that thing” and “they should not bend it like that” and “I would not have that in my yard” and, well… sigh.

This got my wife all upset, but her personal concern was actually valid… the antenna will spoil the view. Of course a view with any antenna in it is art to me, but we have spectacular sunsets in our backyard unobstructed by any buildings and my new extension from 16 feet to 43 was going to push her patience. So this article describes how we prepared a new location for the antenna behind the trees, but still in a reasonable location. Lessons learned from the previous installation are applied.

As for my mother-in-law it is quite amazing what folks will say about things they know nothing about to try and let others think they do resulting in everyone knowing they don’t. Foot in mouth syndrome.

Anyway…

When I installed the original pipe in the ground I learned several lessons and continued to hear more good ideas as time went by. Thoughts include:

• Use a 2 inch OD metal pipe for the antenna stake
• Use gravel rather than concrete
• No Weeding

Let’s explore each point in detail.

Use a 2 inch OD metal pipe for the antenna stake
DX Engineering has clamps designed for this diameter – I found black plumbing pipe 1-7/8 inch OD (1.5 inch ID) which seems to be good enough.

Use gravel rather than concrete
This is an idea learned from one of the many ham email reflectors I monitor. I considered using concrete to secure the pipe in the ground, but ran across one fellow in a post who suggested using gravel instead. His thought was gravel will continue to settle and pack ever tighter as the pipe wiggles from the load. His concern about pouring a concrete post hole pier is the dirt could loosen around the cylinder and cause antenna tilt which would be difficult to fix; Indeed a proper concrete pier involves a wide and deep foot which creates more work than probably necessary.

No Weeding
A hard core requirement for this new antenna footing is no weed trimmer to maintain it – mower only please. My old antenna location did pretty well in this regard, but grass did grow “into” the radial plate from the perimeter requiring occasional hand trimming. This time I want to extend the “no growth” zone to well past the edge of the radial plate.

So my son and I proceeded to create the new antenna base for this new vertical antenna.

Resulting in…

Ground Antenna Mount with Antenna Base

The antenna mount is ready and shown with the bottom components of the DX Engineering 43 foot antenna system.

One good idea expressed by a local club member is to define the edge of the circle with landscaping edge material. This will help keep the rocks in and the grass out. This is a great idea and I did just that. Thanks Frank!!

Another good idea is to replace the surface gravel with landscape stone or pebbles… perhaps dark brown. This is a good idea and I will probably do it, but one has to ask how much effort does one put in to “decorating” an antenna mount when the antenna itself remains so obvious.

There is currently only one thing that might be an issue with this mount… the ground pipe easily turns in azimuth. This is not too big a deal with a vertical antenna, but could be a problem if there is some kind of directional antenna on this system. Concrete would certainly solve this. I am not too worried about this issue, but felt it wise to note it.

The final result is I have a new location for the antenna which is more XYL friendly, does not spoil the view of our sunsets and is ready to accept my new 43 foot antenna, ground radial installation and coaxial cable routing.

Stay tuned for upcoming posts.

We moved to a new QTH with lots of room for antennas. However, where to put the J-Pole antenna remained an issue. As a temporary measure I shoved it in a eight foot piece of schedule 40 pipe and lashed it to a fence post. I ran LMR-400 coax and found it works pretty well… at least good enough to finally be net control operator on the local repeaters from the comfort of my shack.

During the Virginia QSO party this year I realized 2 meter mobile operations were very important to support. Vertical polarization was in order and this J-pole was just the thing. I shove the schedule 40 solution into a tree atop a fully extended tree trimming pole. The antenna was pretty sad looking and was still much shorter than our house. It was the best I could do though.

Surprisingly, this antenna worked like a champ and I was able to easily work everyone in our county and any neighbor county with no problem on FM 2 meter.

Time passed.

We purchased a cheap Wal-Mart playset for our youngest. After assembly I pondered the obvious… could it host an antenna. The answer is yes and here it is…

Copper 2 Meter J-Pole on Play Set

Here is another view showing some details of how the copper j-pole is lashed to the structure of play set using an old dog leash I found in the yard…

View of 2m J-Pole with Balun

The balun is essential; Its application on this antenna verifies theory and simulation quite well. You will notice the J-Pole has copper pipe extending down to serve as a mount for the rest of the antenna. Ideally only the short vertical (1/4 wave long), the short horizontal portion and the long vertical (1/4 + 1/2 = 3/4 wave long) carry any RF current. The feed point for the RF is a balanced feed quite near the horizontal short at the bottom of the J. You should think of the feed point of a J-Pole antenna as feeding a horizontal dipole 1/2 wave long which is, of course, a balanced feed point. So we have two issues to address concerning feeding of the J-Pole…

1. Converting the Un-balanced nature of coaxial cable to balanced
2. Ensuring that extra copper pipe beneath the J and the outside of the coaxial cable shield do not conduct RF

I originally tuned the impedance of this antenna by moving the copper straps up and down together until my MFJ antenna analyzer measured about 50 ohms. With this done I just started using the antenna as is. In the shack, the antenna analyzer revealed a natural frequency quite a bit lower than the 2 meter band… something like 140 MHz or so.

If theory was right, the outside of my coax was becoming part of the antenna’s length and, thus, lengthening it. Worse, RF was potentially making its way back into the ham shack.

Necessary J-Pole Balun

Wow what a difference. This one little change brought the inside the shack natural frequency of this antenna system from 140 MHz to about 145 MHz… spot on.

The SWR measurements for 146 MHz show under 1.5:1; This is very good for the 146.580 MHz FM simplex calling frequency for the Virginia QSO Party.

The SWR measurements for 147 MHz are under 2:1. This is plenty good enough to work my local repeaters.

There are certainly more elegant ways to provide the balun function to this antenna.

Possibilities include:

• Hollow cylindrical ferrite beads along the coax
• Coax wrapped around a large toroid
• An honest to goodness transformer designed around a toroid

That last option offers the antenna designer an option to raise the impedance of the 50 ohm cable to something higher. This, in turn, would move the tap points on the J up the antenna a bit. To keep things simple, a plain ol’ 1:1 choke balun is all we need and is why the coil choke provides a workable solution.

The performance of this two meter half-wave antenna is confirmed. It is a keeper. The only improvement left is to put it on top of my tower… when I get one

You will find plans for the plumber’s special copper pipe j-pole antennas all over the internet. Some of the plans show the 3/4 wavelength section as two pieces: 1/4 wave section coupled to a 1/2 wave section. There is no reason why this should not be one continuous piece of copper pipe 3/4 wavelength long.

Making an antenna out of copper pipe results in an antenna that gets more distinguished with age. Oxidizing copper turns a shade of brown that pretty much serves as perfect camouflage in many environments. You folks in CC&R deed restricted areas can quite likely sneak one of these up in your yard. If a Home Owner Association busy body questions it, just say it is your Asian metallic art piece and provides the yard with good Feng Shui. This is hardly a pink Flamengo or a velvet bust of Elvis (yes I really saw this in a front yard once) so I think you will be fine.

The J-Pole antenna is a unique design that cleverly attaches a tuned feeder to a half-wave radiator. Good luck on yours.