SKCC 5123T----- FISTS 14979----- Flying Pigs 2331----- NAQCC 3610-----QRP ARCI 14176-----Polar Bear 257

Sunday, November 2, 2014

N4KGL End Fed Antenna Configuration for Rapid Deployment

The combination of an end fed wire and a 9 to 1 unun is very popular. For me I discovered that any wire I tried with the 9 to 1 unun would match with the KX3 internal tuner on any band with or with out a counterpoise. I tried end fed wires with various counterpoises with the KX3 internal tuner and it would match some bands and not with others. I guess it comforting to know in a rapid deployment that you can get a match and start radiating a signal without fiddling with the wires. Now from a scientific view this may be less comforting. I can't make any claims to efficiency or radiation patterns.

The 9 to 1 unun is at the bottom. The box at the top is a LNR end fed matchbox.

The unun I use is from Balun Designs. There is a chart on their site that shows SWRs and various lengths. I don't seem to get SWRs shown but by pressing tune on the KX3 I will get a match. I actually have used the 9 to 1 without a counterpoise and have gotten great reports. However, I do find that it the SWR is more stable and lower if I use a counterpoise. You can get a feel for this by touching the ground terminal on the unun and seeing how the SWR changes on an analyser. I don't think what the wire length or counterpoise is is that critical. I adopted 100 foot as that is how my roll of ribbon cable came. I did go back to the manual and it seems that four 30 foot wires for a counterpoise fits their recommendation.

counterpoise wires spread out.
 As for the wires I use two conductors from 28 gauge computer flat cable for the radiator. This wire is light and well behaved. I can wind it up in figure 8 fashion between my thumb and little finger on one hand. Likewise the counterpoise is a 30 foot length of ribbon cable with 8 conductors. Four radials are slit out. I can
 wind it up in the same way.

Ribbon cable for radiator on left and counterpoise on the right.

Here is the data from a little study I did. SWRs on the right are with my hand touching the ground to see the change in SWR. I take it that if my hand touching makes little difference I have an better ground. The value to the left of the slash is SWR and to the right was the R value on of my Ten Tech FG-01 SWR analyser.

As far as the supports I have been using a Jackite 31 foot pole near the rig and a 20 foot pole at the far end. There are details about those poles at this link.

I get great results on 40 meters with the 100 foot length of radiator.  That is usually why I go with this configuration is to cover my 40 meter contacts. It does work OK on other bands as well.