OCF Masters Articles

We start with a chapter that has most of what you need to know about dipoles to understand how they work followed by a build project aimed at new Technician licensees on building a simple to deploy 6-meter dipole. Another build, Chapter 3, follows what may be of interest to the new Technician as well as those interested in Emergency Services and remote operation, a dual band VHF/UHF J- Pole that can be rolled up and carried in a bag. A version of this antenna is being used on archeological and humanitarian expeditions deep in the Andes.

  The OCFMasters.com team, Bob Glorioso, W1IS, and Bob Rose, KC1DSQ, won their second QST Cover Plaque Award in a year for their article...

This two-element phased dipole beam is designed to be hung between two trees and easily transported. This makes it perfect for ARRL Field Day, Parks On The Air activations, DXpeditions, and more.

Phasing waves, acoustic, radio, radar, etc. is a way of directing energy where you want it.  We have all had the challenge of “phasing” our stereo speakers to get a correct “Stereo Effect.”  We do this by reversing the connection on one speaker, until positioned in the middle of the two speakers, the sound appears to come from the middle.  Similarly, we can adjust the phase of two antennas to put most of our signal where we want it.

The antenna described here is now in its second incarnation. The first version, thrown together to try it out, finally needed to be replaced after being up for nearly 20 years. This antenna has several unusual characteristics. First, it is a full quarter wave wire vertical. Second, the bottom and radials are 10 feet off the ground, thereby minimizing ground losses and making it a very efficient radiator. Third, the design is a bit unconventional as it has only two radials. Why? Well, you really only need two radials on any vertical to provide a balanced counterpoise and two quarter wave 40 meter radials and easier to fit into a small yard.

All hams know dipole antennas for their simplicity and the fact that the impedance of a dipole, about 70 ohms, is a good match to our commonly used 50-Ohm feedlines.  A dipole is most likely the first HF antenna that most of us still use.  Over time, we learn about other configurations like the Off-Center-Fed, OCF¹, multiband dipole whose impedance of around 200 ohms doesn’t match our coax and needs a balun to provide a match to our coax.  If you can feed a dipole from a point off center, why can’t you feed the antenna from the end?

Virtually all hams know dipole antennas for their simplicity and the fact that the impedance of a dipole, about 70 ohms, is a good match to our commonly used 50-ohm feed-lines. A dipole is most likely the first HF antenna that most of us still use.

Many antenna manufacturers specify gain figures in seemingly mysterious terms that are often difficult to interpret. This article provides a framework to assist you in understanding the terms.

Impending Field Day many years ago was the genesis of W1IS’s efforts to build a portable 2-element 40M wire beam. After several years and iterations with more or less success and recent collaboration with KC1DSQ, this latest design met our requirements for a beam that can be hung between trees, easily be moved in a mini-van, have good forward gain, and low SWR. This meant that, because the element spacing depended on fitting into a mini-van, the spacing had to be ten feet, the front to back ratio would be lower than with wider spacing and the configuration would be Driver and Director rather than the usual Driver and Reflector. 

We wanted an effective Field Day antenna, so we designed this portable two-element 40-meter wire beam. The design goal was for a beam with 10-foot element spacing, so the spacers could easily be carried within a minivan. Because of this limitation, the front-to-back ratio is lower than with wider spacing, and the configuration is driver and director rather than the usual driver and reflector. A further small compromise enabled a 50 Ω impedance. 

You might know that a 40-meter dipole is also usable on 15, since 21 MHz is
an odd harmonic of 7 MHz. But as W1IS and KC1DSQ explain, you’re still going
to need a tuner for one band or the other ... unless ... unless you build their
variation that makes the antenna resonant on five bands!

"I built the Hybrid Balun as described by OCF Masters and in a recent article in CQ magazine. The build was easy, I sourced parts from Mouser and b...