My 40 Meter Verticle
|There are many articles about vertical antennas on the web and in books
and magazines. Why another one? Well, why not! Now before you flip on to
the next web site, please read a little farther. Pictures at at the bottom
of the page.
My 40 meter vertical cost me $13.66 in total. With that said, go look up the cost of one that is being sold in the magazines and on the web. $400.00 to $500.00! Wow! These guys are making some good markup!
Features of the K0WA 40 meter verticle
Made out of aluminum tubing
It works and it works quite well. I am impressed with the performance but to be honest with you my 40 meter Inverted-V sometimes does better but then again sometimes it does not. Performance is a relative standard. Lets just say in radiates. I've had quite a bit of success working DX with the antenna.
The Standing Wave Radio (and lets not confuse this with performance) is 1.1 at the low end of the band rising to 1.4 at the high end. So, it plays well with the transceivers.
The antenna is comprised of three lengths of 12 foot aluminum which telescope together. The aluminum was purchased from the Yard Store in Wichita, KS, just 30 miles south of me. The Yard Store has a lot of surplus aircraft aluminum from Boeing, Spirit, Hawker/Beach, Cessna, and Bombardier. A stainless steel sheet metal screw was used to fasten the sections together. The insulator is a four foot piece of PVC plumbing pipe that fits over the base of the antenna. Why so long? Added strength at the bottom of the antenna, that's all.
A ¼ inch anodized bolt and nut was installed about a ½ inch from the bottom of the aluminum tube along the appropriate lock washer. This bolt is from my junk box and came from a now defunct Hygain antenna. A notch was cut in the PVC pipe and was slid down and around the feed bolt. The bolt was placed so a PVC cap end could be attached to the bottom of the PVC slot to make a weather proof connection. I did drill a "weep" hole in the bottom of the PVC end cap.
Washers and another nut were added for a connection. A 3 X 4 inch piece of aluminum sheet was partially formed around the PVC pipe with about 2 ½ inches sticking out at right angles. Hose clamps are used to attach the aluminum sheet. A SO-239 was installed using the appropriate hole. A #12 wire was prepared using a round lug to be bolted onto the antenna connection point and the other end was soldered to the SO-239.
Now I have a feed line connection that can take a PL-259 directly. Why? I remove the feed line from the yard before I mow. I could trench it in, but it is only 30 feet from the shack and seems to be a waste of time and effort. Besides, I do not like coax connections using solder lugs.
The ground system is … well … cheap! In my junk box, I found an eight inch aluminum ring that was taped that threaded with 12 holes. Where is came from, I do not remember. I am the kind of ham that sees something and throws it into the pile knowing someday there will be a use for it. So, with 12 connections point, I installed the radials. I have used other ways to attach radials. Another way is to used #12 or #10 bare copper wire and make a ring. Then I solder the radials to the ring. Cheap and easy.
The antenna is mounted on angle bracket material you will find used in the installation of garage doors. (Back to that in a minute). The angle steel is about 30 inches long and I gently hammered it into the ground about 18 inches. The ring was then installed over the steel angle bracket. Then antenna was then raised and hose clamps were used to secure the antenna to the angle bracket.
I laid out eight radials at first. I used a short piece of flexible wire connected to a large alligator clamp from the ground ring. Now this is a large alligator clamp which I attached to the shell of the PL259 when it is screwed onto the antenna. Now I am attached to the radials and I can detach it quite quickly. (Since I wrote this article, I have attached a copper strap to the radial ring and clamp it to the aluminum sheet with the SO-239 connector)
Radial wire was free! I made friends with a businessman who installs garage doors for a living. Each garage door opener comes with about 95 feet of 18 gauge zip cord for wiring the opener. He uses about 40 feet and many times he does replacements and uses the existing wire. He had miles of this material. Now, I have a least a mile of it…FREE!
Eight radials worked, but not well. Resonate frequency of the antenna was around 7.100. At least that is where the lowest SWR was at about 1.1 to 1. Performance was not all that great but it did work. I added eight more radials to 16. The resonate frequency lowered a bit. I then added 16 more radials. That is when this antenna started to play well. The resonate frequency dropped to 7050 with 32 radials.
My radials were installed laying on the ground in the fall when I mowed my grass extremely short. I used my own homemade yard staples. I purchased about 40 feet of #14 galvanized wire from the local hardware store. I then proceed to cut them in 8 inch lengths and just bent them in half. Made quite a few. I just put one in for every three feet or so. My lawnmower has yet to chew up a radial. After awhile, the grass will grow up around them and they will disappear for site.
There are a lot of hams who have done scientific study of radials. The upshot of the research is that 60 radials in where you start getting to the point of no return of adding more. With 30 radials to 60 radials you get some return, but is it significant and worth while for me to install an additional 30? I decided it was not and started using the antenna is contests and general operating on 40 meters.
This $13.66 antenna (not $495) has met and exceeded expectations.
Vertical Antenna in the backyard
Self-tapping screw to hold PVC Pipe
Feed point from the back
Feed point and radials - note: the radials were place on top of the grass about 4 years ago and now dirt covers them all. A total of 24 radials.