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Showing posts with the label Doublet Antenna.

Simple Ham Radio Antennas--Doublet Antenna. Post #941.

Doublet Antenna (http://www.ai4j.com/Projects/antennas/doublet.com). Author:  AI4J. Accessed on 04 November 2016, 04:15 hrs, UTC. Please insert title URL to read the full article. Comment: One of the best all-around multiband HF antennas is the "Doublet".  This antenna is simple to build, easy to erect in a variety of configurations, and inexpensive. The doublet is basically a dipole cut for the basic frequency of interest and fed with balanced feed line, such as 450 ohm ladder line, 300 ohm television twin lead, or homebrewed 600-ohm balanced line.  The balanced feed line is connected to a balanced antenna "tuner" or to a 4:1 balun/"tuner" combination and then attached to your HF transceiver with a short length of coaxial cable. This arrangement allows the doublet to cover amateur radio frequencies between 80 and 10 meters, depending on the lowest frequency selected. In this post, AI4J outlines the advantages/disadvantages, construction practi

Simple Ham Radio Antennas. The Open-Wire Dipole (Doublet). Post #293

I'm still in the process of restoring my "antenna farm" after the passing of Tropical Storm Iselle on 07-08 August 2014.  I lost a few trees on my Orchidland Estates property, most of which were supporting several HF wire antennas.  I salvaged most of the wire and the 450 ohm feedline from the storm.  While I cleaned up the mess, I erected a simple multiband vertical antenna using a tall Norfolk Pine Tree as an antenna support. Next on the list is the restoration of my approximately 134-ft/40.85 meters  center-fed horizontal dipole.  The antenna is fed with 450 ohm ladder line which goes into a W9INN 4:1 balun and then via a short length of RG-8X coax into a MFJ 941E Versa Tuner II.  This feed arrangement allows multiband coverage from 3.500 MHz through 29.000 MHz. Although the antenna requires two tall supports (trees or masts), construction of the antenna is simple and the dipole doesn't require a ground radial system. Using the general formula, 468/f(