An Asymmetric Multi-Band Vertical Dipole Antenna

Repurposing coffee cans or beer cans as an antenna is a concept that’s been around for a while, but AH6CY has brewed up a variation that puts his stacked coffee cans between a copper tape base below and a capacitive top-hat above.

HIROKI KATO

I have been experimenting for many years with large diameter metal tubes to build vertical antennas. It all started when I built a portable vertical antenna by repurposing Illy coffee cans.1 I have discovered that the larger the diameter of the vertical element, the shorter the element needs to be to be resonant on a given frequency. In other words, the usual formula to calculate the length of the quarter-wave vertical antenna (234/freq in MHz) does not apply. I also learned that the larger the radiating surface, the more efficient the antenna becomes. My latest project, presented here, utilizes a 12-inch diameter construction form made of cardboard for the bottom half of the antenna as well as a stack of Illy coffee cans for the top half (Photo A and…

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CQ Amateur Radio (Digital) - 1 Issue, October 2023

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