Wednesday, October 22, 2014

Simple Ham Radio Antennas: Delta Loop Antenna 40 through 10 meters. Post #315


I found this fascinating article by SV1CDY while I was searching for some multi-band loop antennas. I've used full-wave loops in the past and found them to be easy to build, portable, and cheap. I duplicated SV1CDY's design without resorting to the 56.7 uH coil, since I had enough space in my backyard for a full wavelength loop cut for 40 meters (7.088 MHz). Like SV1CDY, I used some #18 AWG speaker wire for the feedline and connected that line to a W9INN 4:1 balun and then, using a short piece of RG-8X coaxial cable with UHF connectors, I attached that assembly to my Drake MN-4 antenna transmatch. For my version of SV1CDY's short loop, I used #12 AWG house wiring for the loop, three ceramic insulators to support the loop, a 33-foot/10.06 meters MFJ telescoping fiberglass mast, some prepositioned wooden stakes and nylon rope to tie off the bottom of the delta loop, and a 6-foot/1.82 meters wooden stake to keep the feedline off the ground until it reached the 4:1 balun attached to my garage wall. Using the general formula 1005/f (MHz)=L (ft) and a design frequency of 7.088 MHz, I cut three equal pieces of wire measuring 47.26 feet (47 feet, 3.12 inches)/14.40 meters. The delta loop was fed at the lower left hand corner with two-conductor #18 AWG speaker wire from Radio Shack. With the Drake MN-4 in the system, I was able to get a SWR of 1:1 on 40, 20, 15, and 10 meters using my trusty Ten-Tech Argosy II transceiver. I had plenty of contacts on 20 and 15 meters during the day, with some excellent Pacific and mainland U.S. contacts on 40 meters after sunset. This is a great antenna for both home and portable use. And yes, you get to listen to an outstanding jazz track by McCoy Tyner ("Just In Time") while you build this simple, effective antenna. For more details, visit http://sv1cdy.blogspot.gr/2011/10/short-delta-loop-antenna-for-40-to-6.html. For the latest Amateur Radio news and events, please check out the blog sidebars. These news feeds are updated daily. Aloha es 73 de Russ (KH6JRM).