In another long running discussion on QRZ about End Fed Antennas, WA7ARK offered a contribution: (1) Back in post #30 I showed that with a halfwave wire fed close to its end works just like the same wire fed in the center; the only difference being the feed point impedance. I let EzNec figure this … Continue reading Discussion of WA7ARK’s contribution to a QRZ thread on an End Fed Dipole
In a discussion about using a 40m centre fed half wave dipole on 80m, the matter of feed line loss came up and online expert KM1H offered: Use this to help make up your mind. Add it to the normal coax loss. http://www.csgnetwork.com/vswrlosscalc.html This is to suggest that the feed line loss under standing waves … Continue reading Line loss under standing waves – recommendation of dodgy tool on eHam
Hams being innovative come up with a myriad of cheap alternatives for wire for antennas. One of those alternatives is common 0.91mm steel MIG wire. Steel MIG wire is often coated with copper and is claimed by some online experts to “work real good”, particularly as a stealth antenna. But is it the makings of … Continue reading 80m half wave dipole made from 0.91mm steel MIG wire
The so-called End fed Zepp (EFZ) is often cited as the basis for many more recent antenna designs, and is leveraged to provide and explanation… though few hams understand how the EFZ actually works. End fed Zepp Above is a diagram from the ARRL Antenna Handbook (Silver 2011). Though a short conductor is shown to … Continue reading End fed Zepp
A correspondent asked me to review an end fed matching unit that uses a FT82-43 ferrite transformer to transform the high impedance of a 40m end fed half wave down to approximately 50+j0Ω. His design uses a primary (radio side) of 3t and secondary of 24t. Last update: 17th September, 2015, 8:43 AM
A reader of my article End fed wires – new hams love ‘em asked about the performance of the matching transformer described at (Osborne 2014). (Osborne 2014) gives the transformer design above using a FT82-43 ferrite toroid with three turns on the primary. The concept is to adjust the antenna length and C1 for a … Continue reading End fed wires – another matching case study
Hams impoverished for space to erect a ‘full size’ antenna for HF pursue a range of options and end fed wires figure highly. New hams who heard the maxim that ‘any antenna is better than no antenna at all’ will try to use bed frames, window frames, balcony railings, anything metallic to get on air. … Continue reading End fed wires – new hams love ’em
Introduction There are several articles on this site describing EFHW transformers using the Jaycar LO1238 toroid, two particularly relevant ones are: End Fed Half Wave matching transformer – 80-20m – LO1238 variant; and Another small efficient matching transformer for an EFHW – LO1238 – VK3PY, VK3TU build and measurement. This article presents a design workup … Continue reading 1:49 EFHW transformer using a Jaycar LO1238 core – design workup
The article End Fed Half Wave matching transformer – 80-20m laid out a design for a EFHW transformer based on the readily available FT240-43. This article builds an NEC model for an EFHW antenna at 3.6MHz incorporating a realistic model of the above transformer. NEC provides for a NT card characterising a two port network … Continue reading FT240-43 matching transformer for an EFHW – NEC model at 3.6MHz
EFHW exploration – Part 1: basic EFHW explored the basic half wave dipole driven by an integral source as a means of understanding that component of a bigger antenna system. The EFHW can be deployed in a miriad of topologies, this article goes on to explore three popular practical means of feeding such a dipole. … Continue reading EFHW exploration – Part 2: practical examples of EFHW