Posts

In Praise of Wire Antennas. Post #226

Every now and then it's good to stand back and analyze what you've done to your antenna farm.  Is your antenna arrangement fitting your goals? How easy is it to build and maintain the structures that connect you to the world?  Is there a way to make your antenna more efficient without spending a lot of money?  I came to such a crossroads this weekend as I surveyed the rural Puna District home my wife and I are remodeling for our permanent home. After years of living in rental apartments and homes with restrictive covenants, I will at last have an acre of land to build some full sized hf antennas.  I will admit that I've learned a lot about stealth antennas and low power operation during my 36 years as an amateur radio operator.  But now, I have some real space to build antennas with real gain. My main problem was deciding whether to buy a tower, a set of mono band beams, and sophisticated antenna rotating equipment or to stick with my faithful wire antennas which have

An Enhanced 40 meter full wavelength loop. Post #225

When I was first licensed as a novice in 1977, I tried all kinds of antennas.  In the space of a year, I must have built and used 10 or more antennas, including verticals, loops, inverted vees, slopers, and half wavelength horizontal dipoles.  I've always been fascinated with full wavelength loops, but, because of limited space, I rarely built loops except for 15 and 10 meters.  I relied heavily on the standard 1/4 wavelength verticals with ground radials and the inverted vee. Now that my xyl and I are remodeling our future home in the Puna District, I had a chance to build a full wavelength 40 meter loop without worrying about nosey neighbors or lack of space.  Our lot is one acre, giving me plenty of space to experiment with a variety of antennas. Over the past few weeks, I've  built and used a half wavelength horizontal dipole and a half square antenna for 20 meters with outstanding results.  Now it was time to rethink the loop I built 36 years ago as a novice operator.

A 5/8 wavelength vertical for 10 meters. Post #224

How would you like to build a 10 meter vertical with some gain and a lower radiation angle than the usual quarterwave vertical?  You can realize this goal by building and using a 5/8 wavelength vertical antenna on the popular 10 meter amateur radio band. If you use 50-ohm coaxial cable as your feed line, you'll need a matching device at the base of the antenna to make the antenna work correctly.  However, you can simplify the matching problem by using 450-ohm ladder line, a 4:1 balun, and a short piece of 50-ohm coaxial cable connected to the antenna terminal of your antenna transmatch.  The 5/8 wavelength vertical also requires a ground radial system to realize its full potential.  The radial system needn't be an extensive affair buried in the ground.  I used six elevated 5/8 wavelength radials for my antenna.  Thanks to the ladder line, the 5/8 wavelength vertical also is usable on 20 and 15 meters. Faced with a more complicated construction project than the usual quarte

The Bent Dipole or Inverted "U" antenna. Post #223

Have you ever wanted to erect a full half wave dipole antenna for your favorite amateur radio band, but just didn't have enough horizontal space to put the antenna?  This could be a problem for 80 and 40 meter dipoles, which can stretch out to 135 feet/41.15 meters (80 meters) and to 67 feet/20.42 meters (40 meters). According to an article by Claude Jollet (VE2DPE), most of the rf radiated and received by a dipole is concentrated "in the middle 60% or so of the antenna...the ends can be dropped down from the horizontal without much adverse effect." That was great news to me, since my back yard has a maximum length of 50 feet/15.24 meters bordering the rear of my house.  So, if I bent the horizontal dipole at the 60% part of the flat top and let the remaining length hang down well above ground, I should still retain most of the dipoles good qualities. I decided to erect a quickly built bent or inverted "U" dipole to see what results I could get. MATERIA

A Full Wavelength Loop for 40 through 10 Meters. Post #222

Having built a series of verticals, inverted vees, half squares, and loops for my amateur radio activities, I decided to "thin the heard" of my less than successful antenna efforts and concentrate on a few antennas that have given me the most contacts and overall satisfaction. Although I love the ease of assembly and portability of homebrew vertical antennas, I just don't enjoy the labor involved in putting in a ground radial system.  The elevated counterpoise systems I've used have been less labor intensive than the buried radial approach, but, still, there is a lot of wire running around my property which is a safety hazard for children and pets. The inverted vee antennas are being kept for portable and emergency use.  I have a few telescoping fiberglass masts which make raising these antennas an easy task. Since I lack the space to erect a 80-Meter horizontal 1/2 wavelength flat top dipole (the familiar "doublet" antenna), I have put that antenna o