Shortened vertical for the 30 metre band

Sometimes a summit offers little space to deploy an antenna. Either because there isn’t much room or because there are many people at the top – or both.
Then an antenna with a small footprint is required.

While preparing my activation on DL/AL-086 I noticed that it might become difficult to deploy one of my standard antennas due to above reasons. It was also clear that there was only time for a brief single-band activation. Furthermore the whole equipment should be as light as possible. That’s why I built this simple vertical.

Step 1: Cut two pieces of wire, each approx. 7.2 metres long and solder them to a BNC-connector.

2021-07-07 18.18.20
Fig. 1: My standard 6m squid pole is too short for the radiator length of approx. 7.2 meters on 30 m

Step 2: In order to fit the complete wire length on the mast, wind a coil of 9 turns, starting approx. 20 cm above ground and fix it with two rubber bands. The coil has a length of approx. 15 cm. Work as accurate as possible. The dimensions are critical but luckily not extremely.

2021-07-06 17.42.03
Fig. 2: Coil at the lower end of the mast

Step 3: Wrap the remaining wire with a few turns around the squid pole up to the top.

Step 4: Stretch the radial wire away from the antenna. If the radial is lying directly on the ground, the antenna impedance drops to ~ 30 Ohm. Therefore it is more favorable to hold the radial about 20 cm above ground, e.g. with a hiking pole or the like.

2021-07-06 17.41.32
Fig. 3: SWR looks good at the desired frequency.

I set up the antenna twice and found that the results were reproducible when winding the coil accurately. This was sufficient for me to give it a try on a summit.

Ein Gedanke zu “Shortened vertical for the 30 metre band

Kommentar verfassen

Trage deine Daten unten ein oder klicke ein Icon um dich einzuloggen:

WordPress.com-Logo

Du kommentierst mit Deinem WordPress.com-Konto. Abmelden /  Ändern )

Google Foto

Du kommentierst mit Deinem Google-Konto. Abmelden /  Ändern )

Twitter-Bild

Du kommentierst mit Deinem Twitter-Konto. Abmelden /  Ändern )

Facebook-Foto

Du kommentierst mit Deinem Facebook-Konto. Abmelden /  Ändern )

Verbinde mit %s