DK7ZB-Dualband-Beam 12/17 M

The beam has only one feedpoint with 50 Ohm and has an open-sleeve element for 12M

12M: 4,39 dBd 11,5 dB F/B

17M: 4,15 dBd 11 dB F/B

The measurement of the SWR by Phil, ON4TA.

He reports no tuning on 17M, resonance as expected. The dip on 12M was a little bit to high and can be shifted with the 12-m-open-sleeve-radiator.

The scheme of the beam with the currents for 24,9 MHz

Element lengths for the two bands, keep the outer tubes 15 cm longer for the overlap. The open-sleeve-element for 12 m and the reflectors can be mounted direct above the boom (metallic connection), but do not use big metallic brackets. This can detune the beam!

Feeding with a current balun

SOURCE: https://www.qsl.net/dk7zb/2-Ele-Kurzwelle/2-Ele-12_17m.htm