OCF Masters Articles

  • Portable 20-Meter Phased Dipole Beam

    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.
  • Portable Phased Dipoles for 20m

    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.

  • A Suspended Quarter Wave 40 Meter Wire Vertical Monopole

    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.
  • A Deep Dive into End-Fed Half-Wave Antennas (Original)

    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?

  • A Deep Dive into End-Fed Half-Wave Antennas (Published)

    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.
  • My Dipole Has Gain!

    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.
  • Portable 2 Element 40M Wire Beam for Field Day

    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. 

  • A Portable Two-Element 40-Meter Wire Beam

    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. 
  • A New Design of a 40-6-Meter Off-Center-Fed Dipole

    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!
  • Baluns Basics: What’s a Balun? Why a Balun? How Do I Make a Balun?

    “Balun” (BALanced to UNbalanced) is a catch-all term for a variety of devices we use on our antenna-feed- line systems. This article will take a brief look at what they’re all about, why they’re important and how you can build your own.

  • A Simple Dual-Band Upgrade for Your 40-Meter Dipole

    During this lull in the solar cycle, 40 meters has been the best band for both local and DX contacts. Now that the sunspots are coming, other bands will soon be packed with signals as well. If you have a 40-meter dipole that's been your workhorse through the lull between Cycles 24 and 25, this will get you on 15 meters with low SWR and a minimum of effort.
  • End Effect and Harmonic Antenna Design

    This article takes you through the design of a 40 M dipole that many hams also use on the third harmonic, 15 M. In the process it starts with the speed of light and drills down to the realities affecting our antennas including, Velocity Factor, VF, and End Effect in our battle to build multi-band harmonic antennas.