Monday, January 23, 2017

Simple Ham Radio Antennas--Antennas for portable operation. Post #1021.

Antennas for portable operation
(http://www.dxzone.com/cgi-bin/dir/jump2.cgiID=32473).
Accessed on 24 January 2017, 00:45 hrs, UTC.
Author:  MyHyEndFed Antennas.
Please click link or insert title URL into your search box to read the complete article.

Comment:

A short, basic tutorial on the types of antennas best suited for portable operations.  The author does a good job of explaining the pros and cons of portable antennas ranging from verticals to half-wavelength dipoles.

Although there is no "perfect" antenna for portable or emergency use, this post recommends the classic end-fed half-wavelength antenna with a matching unit as the most cost effective and simple to erect antenna for field operations. The original concept of the end-fed half-wavelength antenna goes back as far as 1928 when "QST" ran a series of articles on this multiband HF antenna.

According to the MyHyEndFed Antenna manufacturer, the easily assembled end-fed half-wavelength antenna is an excellent choice for any field exercise:

"If you take a half-wave dipole, eliminate the feedline and feed it directly at the end, you have an antenna that has many of the advantages of the dipole with few of the limitations of other portable antenna methods.   This antenna has been described for years in the ARRL Antenna Book and other amateur radio publications but it has received little attention lately.

Without the feedline the antenna is a snap to put up. Freed of the restrictions of the center feedline, the HyEndFed fits into situations that would be difficult for the dipole to handle.  When erected well of the ground and clear of surrounding objects, it is as efficient as the dipole and it is effective because radiation from it is predictable so that the signal goes where you want it to go.  No tuner,  just hook up the coax and go.

Also, because it is only a single wire with a  insulator  and a little matchbox integrated in the second insulator  the HyEndFed is lightweight and small so it is easy to store and transport - things to consider for portable use.  It doesn't have to support a center feedline so physical strength is not an issue.  A temporary portable telescoping fishing rod antenna mast can be used..

The total overall length of the HyEndFed is an electrical half-wavelength, calculated from the formula L (Ft) = 468/F(MHz) where L is the overall wire length in feet and F is the desired operating frequency in Megahertz."
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Why not try something new for your next portable antenna?  You can build an efficient, effective half-wavelength antenna with materials commonly available at your nearest hardware store or home improvement outlet. This antenna is also useful at homes where there is limited backyard space, since the antenna doesn't require a ground radial system.
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Aloha es 73 de Russ (KH6JRM).