W5TOM's Low Profile Antennas
This Week's Featured Antenna
W5TOM's world famous Multi-band Quadra-Polar Yagarombaomnilog with Parametric Omega matching
section. Made with lengthless wire. Schematic, Jones chart, and parts list available on request.
First A little Background
Overcoming neighbors and deed restrictions.
I moved here knowing that antennas were going to be a problem. Just like the house I vacated (a few blocks away), theoretically I wasn't supposed to have any antennas at all. From my previous house, I realized that I would be ok if no one complained. The first thing I did was put up the off center, ladder line fed dipole between two large oak trees. It is 35ft. high and that webbed, 1 inch ladder line is pretty conspicuous. I started immediately shoving 600watts of SSB into it. I had some minor problems with RFI in the house that were quickly resolved. Unfortunately, it was visible from the street. After a couple of days of activity, there was no static from the neighbors. About one week later I met a neighbor that was down the street a few houses, that commented on the antenna. He made it clear that he knew that it was an antenna, and that I wasn't supposed to have it. He had a jerk attitude about him, and I thought he might be trouble. No one else even noticed.
I figured that I'd better prepare for what might be coming. This guy could be trouble. He couldn't even see my antenna from his yard, he would have to walk down the street. And as you know, as soon as the authorities get involved, everything gets more difficult. I had to come up with a plan, realizing that I could be out of the Ham business for good. I was not going to give up without a fight, so I got a copy of the deed restrictions. I noticed that no window AC units could be used. After some snooping, I also noticed a couple, barely visible on the block. Weapon #1. I wouldn't take my antenna down until the AC units on the block were removed. Still planning for the worst, I needed an exit strategy. I had approx. $8k invested in Ham gear, and I figured I could get at least $4k in a quick sale, since it was all pretty new stuff.
While picking up some mulch for my wife at the local nursery, I noticed some pink flamingos with whirling wings for $19.95 ea. I asked the owner to find out what they would cost if I bought a couple of hundred at once. He eagerly went to the office, and returned with the $12.00 figure. He said he'd pay the tax. My devious little brain remembered that there was no mention of such things in the deed restrictions. When I got home, I figured that my quick Ham liquidation would net me exactly 333.3 pink flamingos with very energetic, obnoxious whirling wings. I have a large front yard (lot is an acre), that could easily accomidate this many visual improvements, if they didn't mind New York subway density. I didn't care, if I had to give up Ham radio, I wanted to leave with a scorched earth manoever that would make the interred Hiram Percy Maxim sit up and cheer. And better yet, the flamingos could be easily seen from my nemisis's front yard if I consentrated them to the right side. Weapon #2 and the exit plan was hatched.
A few days later, I ran into this gentlemen at a neighborhood gathering for National Night Out. He brought up the antenna thing again. Now armed with my carefully crafted weapons, I told him about the flamingos and the AC units in the sweetest, most diplomatic manner I could muster. He said nothing in response to my situation and asked if he could get me a beer. I said yes. Since then, we have become waving acquaintances, and I have put up two more antennas that have been belching 600 Watts for almost 9 years.
A concerned reader sent me this picture of a bird flu epidemic in Broward County, Florida and warned me that if I were to have to deploy the flamingos, I should have them vaccinated first. Thank you concerned reader.
W5TOM Antenna Farm
Would you believe a small garden?...Would you believe a window box?...How about a flower pot?
These are my 3 antennas with the "end fed Ford Explorer" in the foreground.
They are LtoR: The oak tree containing the vertical oriented, full wave, square diamond 17Mtr. loop. The half wave, end fed 17Mtr. vertical. The asymmetrical, ladder line fed, dipole with tails. And, in the foreground the world famous End Fed Ford Explorer.
This is really stealthy, you can't even see it in this pix. You are looking at it on edge, and it is in the foliage between the two major bifurcations. It is supported from the top corner by a single rope, and spread out on the sides by two other ropes. It is fed at the bottom corner with a 75 Ohm matching coax that is connected to 50 Ohm coax for the 75 foot trip to the shack. The top is at 35 feet and the feed point is at 18 feet. It has a flat SWR at the shack, and plays very well. The wire does not touch the limbs or foliage, and the proximity of same has no effect on performance. It really is a 17Mtr loop inside an oak tree.
17Mtr. Half Wave Vertical
The whip is a military surplus, fiberglass, 6 sectioned whip designed for a field communications trailer. I found it abt. 20 years ago at a Hamfest for $5 bucks. It's been in the air ever since in one form or another. The pole adapter and loading section are home brew. The loading circuit is the childish drawing (I commissioned the 2 yr.old across the street to do it for me) on the right. It's a simple series impedance matching device that transforms the high impedance to 50 Ohms. The whip is an electrical half wave on 17 mtrs. It is on a RatShack push-up pole anchored to the eve of the roof and a pipe driven into the ground, making the top at 50 ft. The inductance in the circuit is a coil that was tuned by stretching and compressing it. Sliding the coax connector up and down the pole with it's hose clamp achieves this. The capacitance is a piece of 1/2 in. copper pipe inside of a piece of 3/4 in. They are attached with some kind of plastic plumbing fitting (discovered at a hardware store with "gizinta gizonta" engineering) that allows the 1/2in. piece slide up and down inside the 3/4 in. The amount of capacitance used is very small. It was tuned using the MFJ analyzer. It is flat across the band at the feed point and in the shack. There is also a 1000 Ohm 10 Watt carbon resistor from the whip to the mast for a DC path to ground. There is a spark gap abt. .050 of an inch there too (above the coil). The tip of the whip has a fuzzy wire ball to bleed the charge in the clouds to ground for lightening protection. The mast is very well grounded in four places 10 ft. apart. I use it mostly on receive with the MFJ-1026 as the auxiliary antenna. This gives me "dual diversity" as well as phasing control on receive. This pretty much eliminates fading signals on 17 mtrs. It also helps on other bands in this capacity, but only for noise reduction.
Four Band Switched Inductance Vertical
The 17 meter half wave is now a 4 band vertical. An old transmitter tank coil has been fitted with an Ameritron remote antenna switch mod. RCS-4 to change the taps on the coil to tune 4 bands; 80, 20, 17, 15 meters. It can be seen deployed in the pix below on the right. I am afraid it required a lot of "gazinta/gazonta" engineering, but it works very well. If someone wanted to manufacture these, they might sell very well if they could stop their customers from laughing.
All Band SGC Tuned Vertical
Well, I can't leave anything alone. This is the latest iteration of the vertical. The above switched inductor has been replaced with an SGC-230 auto tuner. The feed point has been moved down the pole to a convenient eye level. This makes a kinda (technical term) twin lead, balanced feed line on higher frequencies and a longer element on the lower frequencies. If you are a novice in antenna design, the first thing that comes into your mind is, "This guy is a genius, but if you are knowledgeable on the subject, "Damn, what an Idiot!" will be your response. See, I have something for everybody here. Actually, I know more about the subject than is evident, it is just that my approach to antennas design is different than most. I put up what I can get away with and then try to make it make sense...and work if possible.
The diagram on the right along with the pix should make the design evident. The white plastic cover allows shade and ventalation to keep the Texas sun from cooking the poor things little brain. The tuner is powered by a 7 AH 12V gell cell with a Schumacher battery maintainer in a utility closet next to the installation. I abandoned the above switched inductor scheme because it only worked on 4 bands, and not the ones I really wanted. This works on all bands from the bottom of 160 meters to the top of 10 meters with a 1.3 to 1 or better SWR. It tunes in seconds or fractions of a second to any frequency; just say your call sign, and before you finish, it's tuned. The reports I have been getting have been better than expected on all bands. It is very, very successful.
The dipole is made for 20 and 40 meters and fed with 50 Ohm coax in the center. The 20 meter part in the center is made up of 450 Ohn window ladder line. Wire is added on the end on one side of the ladderline to make the 40 meter part. It's like a full sized 40 and 20 meter dipole fed at the same spot and just 1 inch apart. It works very well across the two bands with an SWR of about 2 to 1 at the band extremes. It is streched between two of these God awful trash trees called live oaks and is about 35 feet off of the rock hard nasty red clay that passes for Texas around here.
End Fed Ford Explorer
Yes, the actual antenna is the vehicle. The loading device uses the same circuit that is used on the vertical antenna above. The components are mounted on a phenolic bar, and a strap with a mag-mount magnet on the end. It was originally built to load the St.Louis Arch, a long time, but unfulfilled desire of mine while I lived there (another story for another time). Needless to say, the Explorer was not a great antenna, but I worked several stations with it on 20 and 17 mtrs. one afternoon with S5 to S9 reports. When this is placed on a large structure, say a fire tower, or tall lamp pole, or even a building plumbing system, the results are quite impressive. Boy, I wish I could have done the Arch. These days anyone sidling up to a monument or building with a bag containing electronic equipment, and attaching an unknown device would definitely draw automatic weapon fire. Unfortunate.