Necessity is the Mother of Invention
As any amateur living in an antenna restrictive community knows, it is difficult to say the least to erect and have an antenna system to accommodate their interests in amateur radio communications. I am sorry to say that too many people do not realize the benefits amateurs provide to their communities on a daily basis throughout the world.
My home is in a retirement community of over 700 homes that does have these covenants but fortunately are not as restrictive as some amateurs experience. It was only with proper investigation of all the written rules and regulations of my community prior to the purchase of my home and discussing with the community owners of what I thought was a reasonable antenna system that I was granted permission to erect my antennas in the back yard of my home.
I offered to provide my retirement community emergency communications if needed and insured the community owners and the homeowners association that my antenna installation would be neat and professional in appearance as well as safe. I also insured that all measures would be taken by me to prevent any rf interference within my control. It was with these efforts and some neighborly education of others residing in my community that I have been fortunate enough to enjoy my amateur radio experience.
With all the above in mind, I set up my antenna systems for my radios in the back yard of my home. I found that I did not have room to erect a back up antenna for emergency communications on 70cm with local repeaters. I had to stop and think of what to do….. do I ask permission to stray from my agreement and risk it all or do I become innovative? I know immediately some would say “be sneaky”.
I prefer to say that I was “innovative” in solving my problem and had my neighbors in mind when I found my solution. My answer was in the flag pole at the front of my home. The flag pole was located and supported by the corner of my carport. The flag pole was a twenty foot high aluminum pole with a hollow gold aluminum ball at the top. A typical flag pole indeed.
What could I do to utilize this pole yet not put up an antenna that would draw attention to itself? I found the answer when I examined the ball at the top and found it was constructed in two pieces, a top half and a bottom half. Now the idea was beginning to form. A weather vane! A small gold weather vane would look nice on top of the ball.
A few sketches and some calculations provided a quarter wave 70cm ground plane antenna that looks like any other weather vane as the accompanying picture shows. Did you wonder where the coax feed line was? It enters the flag pole at the top, runs down the inside of the pole and exits at the roofline near the gutter. The cable then runs in the gutter, down inside the downspout at the rear of my home where it enters my shack along with my other feed lines. Completely out of sight.
This is a working weather vane too! The antenna was constructed from pieces of stainless antenna rods from long forgotten antennas cut and tuned to frequency with my MFJ-269 analyzer. The holder for the four ground plane elements is a NMO ground plane adapter with set screws from Larson which screws onto the bulkhead fitting supporting the vertical element. The wood letters were purchased from a local craft shop and glued with epoxy to the end of the ground plane elements.
The vertical radiator was a piece of stainless antenna rod silver soldered into the center conductor of a Pl-259. The interior of the PL-259 was filled with epoxy for support and insulation. This was then connected to the bulkhead adapter in the top half of the flag pole ball. The coax is connected by a PL-259 to the bottom of the bulkhead connector inside the ball.
The coax exits the bottom half of the ball and immediately enters the interior of the flag pole itself. The ball halves are held together after assembly by eight small sheet meat screws.
The wind direction indicator or arrow is 3/8” diameter wood dowel with 1/8” thick plywood for the pointer and feather. A piece of plastic tubing was installed through the balance point of the direction indicator so as to slip over the vertical radiator and provide free movement. All glues used for construction were epoxy. Once construction was completed, the entire assembly was spray painted with three coats of “non-metallic” gold colored paint. The use of “non-metallic” paint is to prevent conductivity and shorting of the vertical radiator to ground.
The antenna works great and should not be expected to have any gain. It’s height above ground is twenty feet. I also installed a ground rod at the base of the aluminum flag pole.
During the construction of this antenna, I did miss one little item that I would have never thought of and this little story will explain this experience.
One night my wife heard an owl outside and went out to see where it was since it’s hooting seemed so loud. She thought it may be after some of the wild rabbits we hand feed. She was standing by the flag pole when the owl hooted again. She looked up and there was the owl perched on the wind direction indicator on the weather vane. It’s feet were firmly gripping the indicator. Having fear for her poor little bunnies, she shooed the owl away. As the owl started to fly off, he did not immediately let go of the indicator and pulled it up and off the vertical element. As soon as the owl realized he had extra baggage he let go and the indicator fell to the ground after bouncing off my wife’s head. No damage was done and we laughed at the experience. I replaced the indicator and this time placed a little clamp on the vertical radiator to prevent another happening.
It is to be noted that several of my neighbors have asked if I would build a weather vane for their flag poles as well. They said that mine was really neat. I am just finishing another like antenna for two meters for a amateur friend for his flag pole in another community. Tuning was a little more critical as the ground plane elements were kept short so as not to appear any different than the 70cm antenna. The vertical radiator was kept at Ľ wave for 2m and is very hard to see at 20’ above ground.
This antenna idea may be of some help for amateurs that have a flag pole and want to have an outside antenna for VHF or UHF frequencies. The weather vane can also be attached to the peak of a roof if a flag pole is not available.
73’s
to all.
John E. Conefrey,
W4IVW