J-pole antennas for HF bands

Introduction

I’ve been using J-pole antennas on the 2m band from the first day I got licensed. They perform very well, are easy to construct and are cheap. Since Adrian PA0RDA and I have been experimenting with vertical antennas for HF, we came to the idea to try those J-poles on HF.

This idea is not new. Many radio amateurs have tried this before, like DK7ZB. The J-pole antenna is almost identical to the Zepp-antenna, which is a still a popular HF-antenna.

Construction

We made each J-pole of a single piece of wire. The length (l) is equal to the wavelength (wl), minus compensation due to velocity of propagation (v). At 3/4 length the wire is bended 180 degrees and goes back up again, at a distance (d) from the other side. The length of the wire is:

l = (wl * v) + d

Here are some measurements we have used:

HF band wl l (v=0.95)
17m 16.56m 15.81m
30m 29.63m 28.23m

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