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Inverted L Antenna for CQ WW


Topband with its wavelenght 160m is not very easy band. Dimensons of antennas are extensive. For MW9W contest crew I have prepared simple but effective antenna for 160m – the Inverted L antenna. It’s based on the material DK5WL „Invisible“ DX Antenna for the Low Bands.

The Inverted L antenna is simple quaterwave antenna with a shape of inverted L letter. Most transmitted energy is vertically polarized. That’s an advantage for DX contacts.

Jirka OK5IM is selling fibreglass poles with total height 12,5m. I bought two and prove the antenna in the IARU HF Championship with impressive result. Try it too!

Dimensons are explained on the picture. During my initial testing was resonance on 1850kHz. The impedance of 12,5m tall vertical antenna on the 160m band is around 12 Ohms. The impedance in the feeding point is sum of this impedance plus impedance of the grounding system.
When using two – three radials you can get total impedance near 50 Ohms – ideal for direct feeding with good SWR. Effeciency will be low (24%)when comparing with ideal non-loss vertical. But nobody own so good antenna, HI. Ground losses has a positive effect on the bandwidth. Bandwidth for SWR below 2 is around 90 kHz.

Big advantage of this antenna is that it could be erected in one person easily. The SWR below 1.2 can be achived when is radiator tunned in the resonance and radials are fitted to match 50 Ohm.

In the IARU HF Championship I have sucessfuly proved Inverted L antenna. Try it too!


Antenna between houses

Pole in the garden