Welcome to the Mountains.....
And Amateur Radio Station WDØM


Let's talk Antennas!

Inverted Ls and Vs, Slopers, Linear Loaded
and Other Antennas to Connect you to the Ether
(And Have a Beverage While You're At It!)

There are SO many types of antennas to choose from. I knew the standard dipole and inverted V antennas would work, but I also wanted to try some different antennas I'd read about in various publications, such as the ARRL "Antenna Handbook", and ON4UN's "Low-Band DXing " - both excellent sources of information on building antennas.

I was interested in 160 meters and 80 meters and decided to try the "linear loaded" 160 meter antenna, as well as a nifty antenna called the "Wermager 80 meter sloper". Both held great promise as antennas offering exceptional bandwidth at low SWR.


The Inverted L

I decided to put up two antennas for 160 meters to compare their performance. The first is an Inverted L. The length of wire required at 1.835 MHz is approximately 127 feet. I used one of the pulleys on my tower to raise the vertical section to the top of the tower, then ran the rest of the wire horizontally to the top of a tree.

Using a slingshot, I launched a heavyweight UV resistant string over the top of the tree, then hoisted the wire, connected to the string with an insulator. It worked just fine. An antenna tuner must be used with the Inverted L to assure a proper match when operating away from the resonant frequency due to the narrow bandwidth.

A good radial system is also required for increased efficiency in operating. I have 40 #14 insulated copper wires, each 50 feet long running out in an array under the tower to provide a good RF ground system. The next project (below) was a Linear Loaded Sloper.



160 Meter Linear Loaded Sloper

The Linear Loaded 160 Meter Sloper turns out to be a great antenna with low SWR over a wider bandwidth. The sloping element is soldered to the center conductor of the coaxial cable, and the shield is bonded to the top of the tower.

The sloping element is 65 feet long, and slopes away from the tower until it reaches the 20 foot level, where it doubles back toward the tower, and then heads back out in the direction it came, spaced 6 inches below the first horizontal element.

There is no electrical connection at the "open end" of the lower element. The horizontal sections of the driven element are 42 feet long, and approximately 6 inches apart.

I used a "straw and string" approach to ensure that the elements maintained a fixed distance apart. Run a piece of string through the straw, and then tie it to the elements, to keep them properly spaced apart. I've found that this antenna loads easily, and seems to out perform the Inverted L antenna.



The Inverted V - Multiband Antenna
for for 80, 40, and 30 Meters


The inverted V antenna is essentially a dipole antenna that is about 5 percent shorter than a standard dipole, and slopes toward the ground, rather than being parallel to it. I decided to use a multi-band approach so the antenna would work on 80, 40 and 30 meters. I made three dipole antennas cut to the appropriate length for resonance in the band segment I wanted to operate (CW).

I connected the wires to a balun (there are three wires connected to each side of the balun) and ran a coaxial cable down to the antenna relay in the junction box. A rope attached to the balun allows me to raise and lower it with a pulley at the top of the tower.

I attached a rope to the longest wire (80 meter dipole), and again used plastic soda straws and string to tie the remaining wires to the longest wire so they are supported at a fixed distance away from the 80 meter dipole.

The ropes are tied to trees so that the angle of the wires to the ground is approximately 45 degrees. Although a compromise, this antenna works very well on all bands. Using my antenna tuner, I can operate operate in the SSB portions of the band on 80 and 40 meters (30 meters is CW/digital only, and the antenna is wide-banded enough not to need a tuner).


Wermager 80 Meter Antenna


The concept of a broad banded 80 meter antenna is very appealing, and the Wermager (described in the ARRL Antenna Book) makes that claim. It promised a low SWR across the entire band, and seemed to be easily constructed.

The 78 foot long sloping element is bonded to the top of the 55 foot tall tower - there is no connection to the coaxial cable used to feed the antenna. The end of this sloping wire is only one (1) foot above the ground.

Each of the horizontal wires is 53 feet long, and is parallel to the ground. Both of the horizontal wires are soldered to the center conductor of the coaxial cable, and the shield is bonded to the tower itself.

The coaxial cable is attached at the 13 foot level of the tower and the horizontal wires depart from there. I tied the horizontal wires to some trees, and spaced them apart using UV resistant string to ensure they are at the proper angle from each other and the correct width apart at the open end.

The sloping element from the top of the tower bisects the two horizontal wires as it approaches the ground. This antenna works as described, and the SWR is lower than 1.5 across the band. I'm VERY happy with this antenna!


40 Meter Half-Sloper

I was intrigued by a Half Sloper antenna for 40 meters. Easily put together, the coax runs to the top of the tower, where the shield is bonded to the tower. The sloping element is 1/4 wave long, and slopes to the ground at about a 45 degree angle.

This antenna is a little harder to match for a low SWR than the others, so I used a tuner exclusively. That is the challenge with a 1/4 wave sloper. It does appear to offer gain in the direction of the sloping element. The approach I used with this antenna was to spend a lot of time getting the SWR as low as possible to present a good match. It's a bit touchy, but once tuned, works well.

Not only was the length of the radiator an issue, but the slope of the wire to the ground also changed the impedance. Using a good antenna analyzer pays off when trying to get this antenna to "play".




Grab yourself a "beverage"
and build a "Beverage"!



Beverage Antennas
for the Low Bands
- a RECEIVE ONLY Antenna

The Beverage antenna is an "ancient" antenna, named after the gentleman who discovered it. Essentially, it is a VERY LONG antenna, typically placed at a level of 10 feet or less above ground. The Beverage antenna is referred to as a "wave" antenna, and is directional, if terminated with a resistor, in the direction it is aimed.

Since I have lots of deer and elk wandering through my property, placing it at a height where the critters could end up wearing it wouldn't improve their demeanor, nor reception on the low bands. I discovered that when placed ON THE GROUND, it is known as a "snake" antenna. And that is what I did. That flies in the face of most antenna concepts, where higher is better. But I'll be darned if it doesn't WORK!

The benefit of this antenna is that it eliminates or reduces the static and leaves only the signals you're trying to hear , providing a better signal to noise ratio. I use it on 160 - 80 meters exclusively as a receiving antenna. It also improves 40 meter reception, but nearly as dramatically.

The diagram (right) demonstrates the general layout of a low band Beverage antenna system that may be switched for improved reception in two directions. If you terminate the wire at the end, it will be directional, favoring the signals coming to you from the direction it is pointed.

If you do NOT terminate the antenna, then reception will be from both directions for that particular Beverage wire. Having two Beverage antennas, selectable with a relay, lets you choose the direction you want to listen to.

There are very few "tricks" to putting this antenna together. At the far end (one of mine is aimed toward Europe) of a 275 foot long #14 wire, solder a 470 ohm, 1/2 watt non-inductive (not wire wrapped) resistor to the end of the wire, and then connect it to a good ground system.

An antenna analyzer will let you determine the appropriate terminating resistance (470 ohms is a good start), as well as the exact number of turns of wire on the toroid to provide a 1:1 SWR.

Construct a simple matching transformer consisting of a number 43 or 77 toroid and 12 turns of wire wrapped around it. Leave a tap (bare wire) after the third turn to provide a ground connection for both sides of the transformer. The earth serves as the common "return" for the ground side of the antenna. The transformer matches the 470 ohm impedance of the Beverage antenna to your 50 ohm receiver.

At the receiving end, I attached the ground wire from the toroid to the single point ground rod for my station. After I found out how well the Beverage works to reduce static (QRN), I put in a second Beverage aimed toward the northwest and use a small relay to switch between them. The second Beverage isn't terminated, and I can hear stations to the northwest, as well as stations in Central and South America FAR better than I had imagined with any of the other 160 and 80 meter antennas I'm using.

Final thoughts: This is a RECEIVE ONLY antenna. Don't be too concerned about obtaining a perfect 1:1 SWR - even with a 2:1 or higher SWR, you'll notice very little difference in the received signal strength. I encourage to give it a try and not be too conerned about theory - practical results are what matters.

Since 160 meters is primarily open during the winter, I leave the antennas on the ground until spring arrives - pick them up - and put them back in the fall. Since the "snake" antenna isn't mounted on supports, it's easily moved as well, to give you coverage toward different parts of the world. Give it a try - and have fun!

73,
Joe
WDØM