Double extended Zepp antenna

The double extended Zepp antenna (Fig. 6-19) provides a gain of about 2 dB over a dipole at right angles to the antenna wire plane. It consists of two sections of wire, each one of a length

Typical lengths are 20.7 ft on the 10-m band, 28 ft on the 15-m band, 42 ft on the 20-m band, and 84 ft on the 40-m band. The double extended Zepp antenna can be fed directly with 450-Ωtwin lead,  especially if a balanced antenna tuner is available at the receiver. Alternatively, it can be fed from a quarter-wavelength matching section (made of 450-Ω twin lead, or equivalent open air parallel line), as shown, and a balun if coax is preferred. The length of the matching section should be

The double extended Zepp will work on several different bands. For example, a 20-m-band double extended Zepp will work as a Zepp on the design band, a dipole on frequencies below the design band, and as a four-lobed cloverleaf antenna on frequencies above the design band.

From Practical Antenna Handbook - Joseph P. Carr