Monday, January 2, 2012

Vertical Antenna Installation

Oftentimes, when I am on the air, people will ask me about my antenna.  This post will detail what I have done for my primary antenna, a ground mounted vertical.  On my primary antenna is described as follows:  a BigIr vertical planted on about 335 square feet of hardware cloth and approximately 700 ft of wire. 
The following information will help you understand what I have done.  I am sure that there are things I could have done better.  But, this is the best install of this antenna yet.  And yes there is at least one thing I would change.

I live in a suburb with a very small backyard.  The grassy area of the yard is 16 feet wide by 18 feet long.  There is a sixteen foot wide by four foot deep garden bed at the end of the 18 foot length.  This effectively makes the total length of the backyard to be 22 feet long.  The yard is bound by a six foot high wood fence.  There is a concrete driveway on the other side of the left hand fence.  There is also a six foot wide grass easement strip on the other side of the fence at the garden bed end of the yard.

BigIr Vertical by SteppIr
Radial plate by DX Engineering
Approximately 335 square feet of hardware cloth, in rolls that are 3 feet wide by 25 feet long.
Approximately 700 feet of insulated wire,
Lawn staples

The original concept was to lay down three strips of hardware cloth and tie them together with insulated wire radials.  This evolved to include two more strips of hardware cloth that were “stitched” onto the original three strips using some of the insulated wire.  I do not have any photos showing the five strips but there are photos showing the original three strips stapled down on the ground.  I used the additional strips to fill in the gaps.  The additional strips do not go under the fence like the originals do.

The first photo shows, the view from the house of, the antenna installation.  The driveway is on the other side of the left hand fence.  The six foot grass easement strip is on the other side of the fence behind the antenna.  You can see the original three strips of hard ware cloth on the ground.  You can also see the bricks used to define the edge of the garden bed.  The bricks were set in place after the three original strips of hardware cloth was run.  The deck sits on the edge of a concrete patio.  The original three strips of hardware cloth start approximately 2 feet out from the deck and run the length of the yard and under the fence.  When I added the overlapping strips they also started at the two foot mark and ran to the brick border. 
I originally planned on only the three strips to clear unmovable things such as plants, fence posts etc.
This photo shows the base of the antenna.  Note the service head in the forefront of the photo.  The coax and antenna control cable run through buried conduit to this location.  Also in the forefront is one of the three guys.  This one runs to an earth anchor.  On the back right of the photo and front right you can just see two of the four three feet long pieces of all threads sunk into the ground as ground rods.  Heavy insulated stranded wire runs from each piece of all thread to the radial plate.
On top of the EHU is a one to one unun.  The goal is keep all of the rf out of the shack.
The mulch was laid after the hardware cloth was run through the garden bed and under the fence.  The mulch is laid down on top of layer of weed cloth.

The next couple of photos will show the path of the conduit, housing the control cable and coax, and entry into the house.

In the photo above, you can see the trench the conduit is buried in.  Before I put the conduit in the trench, I placed a layer of gravel in the bottom of it to raise the conduit off of the dirt and to allow water to drain.  

This photo shows the end of the trench and where the conduit comes out of the ground starting the run to the house.  Also pictured is that infamous party guy the party poodle checking out the scene.

This photo shows the continuation of the above ground run towards the house.  The conduit is held up with plastic pipe hanger tape.
The conduit runs diagonally under the deck to the far side of the drive way.  It then starts down to the entryway.
This photo shows the final stretches of the exterior conduit to where it terminates into the work box.  The box is screwed into the foundation and sealed around the edges with silicone caulking.

This photo shows the entry way for the conduit and control cable.  You can see some holes drilled and plugged with silicone caulking as well as one piece of coax and the antenna control cable.  I had to use a hammer drill to get through the foundation, note the concrete dust on the ground.  I drilled more holes than needed at this time to allow for possible future expansion of the antenna farm.
Subsequent work on the entry included: 
Drilling weep holes in the bottom of the box and gluing green nylon scrub pad over the holes.
Adding an access hole on the right side of the box to run in the coax from my wire antenna.
The work box seals with a cover with rubber gasket.
In the garage the coax and control cable run through conduit, along the base of the slab, to the wall at the front of the garage.  My shack is located on the other side of the wall.  I cut through the wall to mount two gang boxes, back to back with the backs cut out and the boxes, glued together.  I covered each box with an appropriate cover and used six inch bulk head connectors to go from the garage to the shack.

So far we have looked at the overall antenna installation and the coax / control cable run.  Let’s take a look at the hardware cloth and radial wires.  You have previously seen a photo that showed the three primary strips of hardware cloth in the yard.  I mentioned earlier that I used approximately 700 feet of insulated wire in the installation.  The wire is used in two ways; as radials and to “stitch” the hard ware cloth together.  Let’s take a look.

This photo shows some of the actual radial wires.  Note they are laid out in straight lines and thread their way through the hardware cloth. The next two photos will show how the strips of hardware cloth are “stitched” together.
Some of the stitching, across a wide expanse of lawn.  I later laid down overlapping strips of hardware cloth to cover the open ground and used a similar stitching to tie them to the original three strips.
Another shot showing some of the stitching.  At this time all of the strips of hardware cloth have radial run through them and are subsequently tied together.
Earlier in the post I mentioned a grass easement strip and the location of the driveway.  The next photos will look at this area.
This photo shows some the edge of the drive way, some of the radials running through the hardware cloth, and some of the stitching binding the strips of hardware cloth together.  You can also see how the hardware cloth was run under the fence.
Same basic shot but showing the detail of the radials and stitching in a closer shot.

Another shot showing the “stitching”.

And the last photo shows the original three strips of hardware cloth.  Again you can see how the hardware cloth runs under the fence, the radials and some stitching.  These strips also had overlapping strips of hardware cloth stitched onto them.  You can also see the concrete alleyway that borders one side of the easement.

In doing this installation I did not bond each layer of hardware cloth to each other.  There is practical limit to how much time I have and physical limitations as to how much time I can spend bent over.  I did solder ring terminals to the ends of each radial.  Right or wrong; I did rely on skin effect and proximity effect for the ground screen and wires to interact with each other.  Most but not all of the wires used for stitching attach directly to the radial plate.

I mentioned at the beginning that there is one thing I would have done different.  When I tied everything into the radial plate I used ring terminals for the wires and tried to bolt as many of the squares of hardware cloth to radial plate as I could.  Next time I will come up with metal clamps to tie the hardware cloth to the radial plate in an attempt to get greater bonding. 

Final thoughts
There were no measurements take of ground conductivity or anything else. I can tune the BirIr to 1:1.1 swr on all bands, 40 through 6 meters, except for 17 and 6 meters.  I may need to lay down a couple of dedicated radials for these bands.  17 and 6 meters currently run approximately 1:1.4 to 1:1.6 swr.

I have read and heard comments that hardware cloth will rust.  I am sure it will in time.  I can only say I previously used some hardware cloth in a similar installation and it was still good four years later.  The current installation was completed in April 2010 and is still going strong.

I do not claim by any stretch of the imagination to be an antenna guru or have a great deal of knowledge.  I am still learning.

If you should use any of this information, your mileage may vary.  I hope it works as well for you as it has for me.

If I can answer any questions please do not hesitate.

If you can share any observations good or bad about this install, please do.

Until next time.
Good DX and 73
Leslie, AD5WB
Galveston Island, Texas