Yes Cec, to use a vertical 1/4-wave line is a neat way of shorting and
opening a horizontal wire at a single frequency from ground level.

I once used a sealed reed relay to do a similar job. One of the horizontal
antenna wires was in fact twin 20-gauge speaker cable to operate the relay
coil. The shack end of the twin wire required a bifilar choke wound on a
ferrite rod to separate RF from the DC relay supply.
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Reg, G4FGQ