---------------------------------------------------------------------- THE ZIG-ZAG SKYWAVE ANTENNA ------------------------------------------------------------------------ Featured in the March, 1992, issue of RF DESIGN magazine, an article by Bernard Feigenbaum, A FIELD EXPEDIENT BROADBAND HF ANTENNA, shows how to make a log-periodic antenna for shortwave! THAT's RIGHT, a log-periodic, which means several dB of GAIN over a very wide bandwidth. Yet about all you need are a hefty length of copper wire, something like a flagpole or a tree or anything with some elevation to it, and a hank of nylon cord or other insulated rope. Here`s what the danged thing looks like, if I can draw it right for you: o|* /||\ * / || \ * Direction of Main Lobe / || \ * ---------------------> GAIN / || \ *o / || \ /\ * / || \ / \ * o / || \ / \ /*\ / || \ / \ / \ * o / || \ / \ / \ /*\ o / || \ / \ / \ / \ /*\ Z__________||__________\/________ ___\/_________\/_____\/___Y_X____ G o o o o G G Note: Space does not permit the display, but there are seven points "o" at ground level and eight above ground. In other words, there are eight "triangles" in the featured antenna while only five are shown above. Not shown is a simple three-legged ground counterpoise which starts at Y and fans out approx 30-degrees along the length of the antenna. The middle counterpoise wire runs straight between the G below the Y to the G below Z. The other two fan out slightly on either side of the antenna over its length. Legend: || || = Mast, tree, chimney top, anything with some height, say 40' & up \/ = Continuous length of copper wire * = Nylon cord or rope, insulated Z = Termination resistor, roughly 400-600 ohms __ = Ground level o = Insulated hangers to support wire Y = 9 : 1 Broadband Impedance Matching Transformer X = Transmitter, Receiver or Transceiver G = True Earth Ground Connection The far end of the Zig-Zag Skywave Antenna is terminated in the characteristic impedance of the antenna, typically 400-600 ohms, to ground. The feedpoint at the short end is matched with a 9-to-1 Broadband balun and fed with the transmitter or receiver of choice. No portion of the wire is permitted to be grounded except through the termination resistor at the far end and the balun at the feedpoint. The broadband gain of the antenna is reputed to be around 3-dB which greatly exceeds that of a random longwire and most trap dipoles. The Gain Bandwidth is at least 2-30 MHz. US Patent No. 4,733,243 was issued for this antenna on March 22, 1988, and is available by means of Technology Transfer Agreements between the US Army and industry. NOTE: I will be glad to send a complete copy of the article to anyone interested who will be so kind as to include a Self-Addressed, STAMPED business sized envelope and TWO loose extra 1st Class Postage Stamps. Foreign inquirers please include a #10 self addressed envelope and three IRC's for surface mail or five IRC`s for Air Mail. Inquire to: Bill Cheek PO Box 262478 San Diego, CA 92196-2478. Other info may be available from : RF Design Magazine PO Box 1077 Skokie, IL 60076.