End Fed Half Wave matching transformer – 80-20m

A prototype broadband transformer for a End Fed Half Wave operated at fundamental and first, second, and third harmonic is presented. The transformer comprises a 32t of 0.65mm enamelled copper winding on a FT240-43 ferrite core, tapped at 4t to be used as an autotransformer to step down a load impedance of around 3300Ω to … Continue reading End Fed Half Wave matching transformer – 80-20m

End fed half wave matching – voltage rating of compensation capacitors

The so-called End Fed Half Wave antenna system has become more popular, particularly in the form of a broadband matching transformer in combination with a wire operated harmonically over perhaps three octaves (eg 7, 14, 21, 28MHz). The broadband transformer commonly uses a medium µ ferrite toroid core, and a turns ratio of around 8:1. … Continue reading End fed half wave matching – voltage rating of compensation capacitors

End Fed Half Wave / Inverted L / Half Wave Dipole

The popular End Fed Half Wave is all things to all men, but this article compares an End Fed Half Wave, Inverted L, and Half Wave Dipole with some common parameters: frequency: 7.1MHz; flat top length: 20m; Height above ‘average’ ground (0.005,13): 10m; lossless balun / matching device. Key differences: ground connection: Inverted L = … Continue reading End Fed Half Wave / Inverted L / Half Wave Dipole

The magic of End Fed Half Waves (EFHW)

I have noted recently the increasing popularity of the so-called End Fed Half Wave antenna, though the term often includes harmonic operation of the antenna. It seems that at the heart of common ham understanding of this antenna system is that some kind of two terminal feed device creates a scenario with current on the … Continue reading The magic of End Fed Half Waves (EFHW)

80m voltage fed Half Square matching workup

A correspondent wrote asking about the design of a matching network for a Half Square antenna for 80m, voltage fed at one end. Above is the current distribution on the half square voltage fed. It is essentially two in-phase vertical quarter waves separated a half wavelength, a broadside array. Feed point impedance at resonance is … Continue reading 80m voltage fed Half Square matching workup

Discussion of WA7ARK’s contribution to a QRZ thread on an End Fed Dipole

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

Line loss under standing waves – recommendation of dodgy tool on eHam

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

80m half wave dipole made from 0.91mm steel MIG wire

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