So the antenna farm at M1BXF QTH just got larger with the addition of a 40m 1/4 vertical. I’d been thinking about this antenna for while as verticals are good for DX, more in this in a moment, and require little space to erect, but does need space for radials.
The antenna is based on a 10m fiberglass pole for the vertical element support, 17 radials and a clothes line ground screw to hold it up. I ended up with 17 radials as I cut one for length then made a ‘jig’ which allowed me to make 4 at a time after, so I made 3 x 4 in the jig + the one I had… I put screws in at each joint of the 10m pole also so there was no chance in it falling down into itself.
As you can see I erected it near some trees, this is mainly to make it less noticeable in the direction of the house which is through the trees as it were. To help make it blend in further I painted the pole Hamerite ‘highland green’.
The radials all connect to a circular copper bar I made which goes round the base of the antenna with a short wire going to the ground of the feed-point. The radiating element ends in a circular crimp, another is also soldered to the SO-239 centre pin so the method of connecting the vertical radiator to the feedpoint is with a nut and bolt, click to enlarge.
Once all was connected up I felt like tuning it, this only took 2 attempts to get it to VSWR 1.07 @ 7.1MHz as you can see in the first plot, the second plot shows the other resonances upto 60MHz so it is usable on 15m (21MHz) also, albeit with an ATU as the VSWR minimum is outside the 15m band. At first the VSWR @ 7.1MHz was 1.2:1, getting it lower was me being picky.
So why is this antenna epic? Well 5 minutes after connecting it up and tuning through 40m I heard VK7AC working a pileup, 3 calls later and we managed 58/57 either way so the first QSO on the antenna was with Australia (Tasmania) @ 17255km, EPIC!!!