Today I finished installing the vertical section of a new 'trapped inverted-L' antenna for the 160 metre and 2190 metre bands to the final height of 17.8m. It is constructed from 4m lengths of aluminium tubes of various diameters giving it a taper from 45mm diameter at the base to 26mm at the top.
I have been making ground-mounted vertical antenna elements for low frequencies for many years and in my experience 18 metres is about the maximum height for this form of construction using light material, as well as being at the limit of what one person can erect. Higher than this and the construction can quickly become uncontrollable during lifting, resulting in disaster. However, I still have about 2m in reserve should I feel bold enough one day to try to increase the height still further.
Prior to erecting the vertical part, I had already connected a 15.8m top wire. I now have to fit the trap and an additional 15m of wire to an anchor point on a 12m pole about 30m away.
The storage box just visible at the antenna base will contain the L-type 'L-C' matching network to 50 Ohm coax cable feedline for operation on the 160m band.
Thunderstorms are forecast here tomorrow; an early survival test !
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