Sunday, 17 May 2015

10m Vertical Dipole Array - brought two new DXCC QRP

I built a 2-element vertical dipole array for 10m on Friday. I am planning to use this antenna (at least the driven element) for the 10m SOTA challenge. I had the chance to test it during the field day of a local club on Saturday and with the good conditions bagged two new QRP DXCCs.

CW150ITU Uruguay cw - 10817km bearing 223deg SW
OD5PY Lebanon - cw - 3612km bearing 109deg E/SE
CX2TQ Uruguay - ssb - 10919km bearing 221deg SW [500W to a 3-el beam] - RST 52r  57s

Vertical Dipole array -10m - beaming SW

FT-817 5W next to the club rig

Design Details of the VDA
I heard of this aerials first from Dom M1KTA, He helped me with some of the design details and tips. I picked some other design ideas from the Force12 VDA aerials and some simulations with MMANA GAL.Some research around the web indicates that these antennas worked pretty well from the beach as proven by a number of DXExpeditions

2x 7m poles,
Driven element is a resonant dipole at approx 28.300Mhz - effective length 4.83m
Dipole centre is made of an expired frequent traveller card and betterqrp 1:1 current balun
Wire - 100m reel 7/0.2 rapid online
passive reflector is  1.05 of the dipole length  - 5.071m
distance between elements -1.5m

dipole centre: card, betterqrp 1:1 current balun

MMANA simulation

VK5JST - VDA measurements

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