Roger J. Wendell
Defending 3.8 Billion Years of Organic EvolutionSM
Antennas!
Kashima Space Center, JapanI've always been fascinated by antennas - broadcast, ham radio, maritime, etc., it never mattered as long as it was an interesting array! So, whenever time permits, I post pictures and descriptions of various antenna systems that have caught my interest for one reason or another. Oh, I also like to caution folks about the dangers of electromagnetic radiation and have a bit more about that further down the page...
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Click Here for my tribute to Morse telegraphy! |
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Click Here for my page about low power amateur radio! |
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Click Here for my page about maritime radio! |
Types of Antennas
In radio systems, many different antenna types are used whose properties are especially crafted for particular applications. These three types are grouped together under common operating principles, following the way antennas are classified in many engineering textbooks:
- The dipole, monopole, array, and large loop antenna types typically function as resonant antennas; in resonant antennas, waves of current and voltage bounce back and forth between the ends, or circulate around a closed loop, and their overlapping sections add and subtract to form standing waves along the elements.
- Traveling wave antennas are not resonant: Their current and voltage waves travel in one direction along the antenna elements and then are absorbed by a resistor.
- Aperture antennas are made of an outer, surrounding reflective surface whose shape concentrates waves striking it onto a small inner antenna; the inner antenna can be either resonant or non-resonant.
Calculating Antenna Dimensions
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Click Here for the W4HN Antenna Calculator for Verticals and Yagis |
KØPV
Drone photo by KØMVB (click on this image for a larger view)Don, KØPV is a longtime friend and ham mentor from my high school days. This photo of his VHF tower was taken by drone over his property in western Kansas.
The vertical on the top is for the repeater he maintains. Directly beneath the vertical is his 14 element HyGain Yagi on an 18 foot boom for 2 meter SSB.
The next Yagi down is Don's 6 element HyGain 6 meter Boomer on a 24 foot boom. Not too clear in the photo is Don's 80/40 trapped inverted "V" with its apex at 45 feet (which Don says also works surprisingly well on 20 meters!)
Interesting to note that the drone had some difficulty taking the photo due to all of the aluminum interfering with the GPS guidance - preventing a closer look.
WBØJNR
The antenna in this video is my 88 foot (26.8 metres) doublet antenna that stretches diagonally across my residential lot. My QTH is located in Colorado's Denver metro area where cold weather, snow and ice can haunt hams (and antennas!) all the way into June. This recording was made mid-morning on May 3rd, 2013 - the nighttime low temperature, a few hours earlier, was 19 degrees Fahrenheit (MINUS 7.2 Celsius).
This recording was made shortly after ice had accumulated on just about everything outdoors the night before. At first I thought it was ice dangling off the antenna but later determined it was some kind of protective coating on the wire, itself, that was peeling off!
In addition to the coating ice had formed over the length of the antenna and had been slowly peeling off as it became exposed to the rising sun.
If you look closely you can see the moon behind the longest piece of dangling string - it was a waning crescent on that date, in its last quarter.
To the right of the dangling piece you can also see the 450 Ohm ladder line and old-fashioned porceiln insulator I use to for this antenna.
Finally, if you look carefully (0:07, 0:16, 0:26) you will see three birds fly through the video's field of view. Throughout the video you can also hear about a half dozen birds as, despite the cold weather, it was springtime!
Nick's 14,267 Foot J Pole!!
On August 14, 2005 I thought I'd climb a 14er to get back into shape after a few days of rain throughout Colorado. I completely forgot about the annual Colorado 14er Amateur Radio Event where "Ham" radio operators work each other from the 54 14,000+ foot peaks around our state. However, as luck would have it, I encountered Nick (N5PRP) and Dawn on the 14,267 foot summit of Torreys Peak operating the event! Nick built the 2 meter J pole out of copper tubing and painted it white - it was securely anchored on the summit, having been moved there from Grays Peak about an hour or two earlier. Nick and Dawn were very gracious in allowing me to operate their station using my own call sign - thank you Nick and Dawn!!
 Nick (N5PRP) & Dawn |
 Their rig & battery |
 J Pole Close-up |
 Roger & the J Pole |
Field Day and Art:
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I took this picture of a fun little hand-held satellite antenna that my club (CQC) uses on FIeld Day each year. This photo is from our very wet and rainy Rampart Range site at the end of June, 2004 - that's my 1993 Toyota just to the left of the antenna... |
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Here's some antenna art I discovered at a park in Loch Lommand, Scotland. |
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Click Here for my station! |
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Click Here for my QRP page! |
Some of my previous antennas:
 My first tower, way back in 1974, age 18 and not too safety conscious... (Photo by Kendall, that's his right knee!) |
 In 2002, at age 46, I started using my climbing harness (Definitely Not recommended!!) - Photo by Tami |
 Looking down the support rope of my Green Mountain doublet - It's about 1/4" diameter (.635 centimeters) |
My old Smoky Hill QTH:
For two decades I lived near Cherry Creek Reservoir, southeast of Denver. Out there, I had 2 meter coverage from Cheyenne to Limon, Pueblo and most mountain communities on the east side of the Continental Divide. HF Coverage, with low power (I usually ran about a watt) was excellent - all of this was achieved with 3 little sections of tower that kept everything about 30 feet above my backyard. Now I live in the foothills, west of Denver, so coverage isn't nearly as complete. Here are photos of my old antenna installation - boy do I miss it!
 15 Element 2 Meter Yagi |
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 Zepp center support |
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 Rotor Control |
 Rohn House Bracket |
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 Rohn 25g |
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 Ham IV Rotor |
Miscellanea:
AA7QC put up this B&W AC5-30 Folded Dipole. It's about 20 feet up and bent at a 60 degree angle making it a bit directional off the short side or Southwest. It covers 5 to 30 MHz continuously, without a tuner, and is fed with 50 Ohm coax through a built-in balun. It's overall length is 65 feet. 
I brought home this GAP Titan for some experimenting but eventually went back to my 88 foot (26.8 metre) doublet with 450 Ohm ladder line. Nothing against the "GAP" but the doublet is a lot easier (cheaper!) to purchase, install and maintain!
My poor wife-to-be and I, back in 1975, took this photo of WWV's transmitter site in In Fort Collins, Colorado. I haven't been back since, even though I live in Colorado, so I have no idea what they're up to nowadays. Nevertheless, I did create a page of time in a feeble attempt to disect that heady little subject...
Dish World
Aren't parabolic reflectors fascinating??!!
Near Castle Rock, Colorado
Submillimeter Array, Hawaii
Carnarvon Shire, AustraliaWhile traveling through Western Australia Tami and I stopped in Carnarvon Shire to look at this 33.5 Metre dish. I believe it was about that time that they were hoping to convert part of its use to SETI but I'm not sure... Having lived in Hawaii I couldn't help visiting Mauna Kea on a return trip!
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Electromagnetic Smog Cell phone and other dangerous radio wave radiation is all around us! by Roger J. Wendell - March 01, 2009 |
Okay, as much as I love antennas and anything related to radio waves I've always had a fear of the radiation being emitted by all the transmitters, microwave ovens, cellular telephones, WiFi, television sets and computer monitors (the old CRT screens emitted a lot of X-rays), and other electronic devices that surround us throughout our lives. It's not that I was so smart, back in 1970 when I started playing with radio transmitters, but even in those days we heard a lot of stories about technicians getting burned in front of large radar installations or birds dying in front of parabolic "dish" transmitting antennas.So, it was obvious, even back then, that the concentrated energy in a radio wave, especially when you're near the antenna or transmitting source, could be quite unhealthy. Later in life, as cellphones became popular, I began to wonder how much damage was being done by holding a communications device next to my skull that was transmitting at a frequency pretty close to what a microwave oven uses to cook chicken!
Since then, all kinds of studies have come out confirming that cellular telephone towers, the cellphones themselves (even when "just" texting), television transmission towers, and all sorts of radio transmitters are just plain dangerous and hazardous to our health. So, I'm using the conclusion of this web page as a warning and remcommendation: Do everything in your power (so to speak!) to use the least amount of radio frequency transmitting energy necessary to complete the communication. This will not only reduce your exposure to unnecessary levels of radio frequency radiation but will also lessen energy consumption and the subsequent emmission of carbon and other pollutants.
And, if possible, try to eliminate transmissions altogether - even if it means giving up your cellphone or turning down a job that has you working adjacent to a large transmitter or antenna. I know these two points aren't realistic in today's faced-paced, hightech world but avoidance makes the most sense - if you can eliminate your exposure to any radiation source you're going to be a lot better off in the longrun!
Finally, as the second mellenium rolled around the American government, and a variety of NGOs (Non government organizations like the American Radio Relay League), were starting to produce meaningful guidelines and rules related to the exposure of radio frequency radiation. In 2002 the American Radio Relay League (ARRL) released a document entitled, Additional Information for Amateurs Completing Form 605 - related to RF Safety Certification. Not to bore you with the details here, suffice to say that the aforementioned ARRL document provided a table for the limits for maximum permissible exposure (MPE) in advance of Federal Communicatiosn Commission OST/OET Bulletin Number 65. The ARRL document, which was printed as a stop-gap measure while the world waited fro FCC Bulletin 65, stated things like, "...amateur operators should follow a policy of systematic avoidance of excessive RF exposure" and "Before causing or allowing an amateur station to transmit from any place where the opeation of the station could cause human exposure to RF electromagnetic field levels in excess of those allowed under [FCC regulationss], the licensee is required to take certain actions."
Anyway, since I, myself have mostly operated at QRP (low power) transmission levels I felt a more immediate danger to my family and me was the use of our cell phones. So, On May 16, 2007, I interviewed Paul Sean Fitzgerald, author of Cell Phone Friend or Enemy on my program at KGNU. During that interview Paul stated,
"Going back to what you [he's refering to me during the interview] were saying with the WiFi and how it's starting to blanket our countries, it's very invisible, Electromagnetic Smog. Think of cigarrette smoke, if somebody smokes next to you, you can see it, you can smell it, you're aware of it. With a cellphone you can not see it. It's an invisible danger but it's very much there and this is the first time in the history of the planet we've ever held an elctromagentic device, that emits radiation, so close to our bodies. Even when radio came out, think about where our radio antennas are, they're all away from us, they're outside our houses, they're outside our vehicles. They're just not so close to us as now computers, cellphones, and other electronic wireless equipment is."Clearly cellphones are a health hazard but I doubt we'll be getting rid of 'em anytime soon. So, take a common-sense approach to cellphone use. Some of my suggestions are that you limit your exposure by reducing the number of calls you make or receive (including texting), use an "ear-bug" with a connecting wire so that you can keep the cellphone and its antenna away from your body (Blue-tooth technology defeats this purpose - that little transceiver plugged into your ear is sending radio frequency radiation straight into your skull), don't use a cellphone inside a car or metal structure (the radio waves bounce around and bombard your body), and certainly discourage children from using cellphones (their skulls are less thick than an adult's and their growing brains and other body tissues are more susceptible to radiation).
A couple cell towers near the Interstate 70 Hogback road cut
just a few kilometres west of Denver, Colorado (I don't know
if they're using that wind-giny, in the last photo for anything
but I guess it's better than nothing!):
 Cellular Radiation Warning |
 Goofy tree disguise |
 Goofy tree disguise |
 Goofy tree disguise |
 Looking up |
 Wind generator on top |
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Click Here for my video of a cellular tower with a wind generator on top! |
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Click Here for my video of a cellular tower disguised as a tree... |
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click Here for information on how to limit your exposure to cell phone radiation... |
 World Trade Center, 1979 by Alan B. Kaplan |
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Off Axis Parabolic:
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I also love Morse code - click Here for the rest of the story! |
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