GD7JWR

Extended Double Zepp Antenna

         17m Version as in use at home QTH

The Zepp, short for Zeppelin is any resonant antenna end-fed by ladder line. A Double Zepp means a center-fed antenna. This extended version provides 3 db gain over a dipole. The double Zepp consists of two collinear 0.64 wave length elements fed in phase. The diagram at the side shows current distribution in a double Zepp antenna 5/8th wave.
The 1.1 balun is used to connect the 450 ohm ladder line to 50 ohm coaxial cable.
The only adjustment is in trimming the 450 ohm line matching section to best SWR.
Shorten about an inch at a time until best SWR is reached. The Double Zepp works well on any of the amateur bands. This Zepp is in use at my home and it is cut for 17m, compared to my G5RV and Windom antennas it certainly does perform very well even better than I thought it would when I constructed it.

It stills performs well on other bands, at 20m the EDZ acts as two slightly long half waves in in phase

Horizontal Directivity Pattern for the EDZ

EDZ consist of two 0.64 wavelength elements

Exhibiting around 1.6-2Bd gain. At 40m it is slightly long 1/2wave dipole. At 15m it exhibits a four leaf clover pattern with minor lobes broadside. At 10 & 12m it acts like two full wave dipoles in phase and produces a pattern similar to 15m. The EDZ can be cut for any band of your choice and will exhibit around 3bd gain on the chosen band.
This same antenna was also constructed for 6m band and exhibited the same great results. 50.150 mhz each leg is 12.57 ft and the feeder was cut at 2.7ft