This is a full-sized half-wavelength horizontal dipole antenna specially designed for field day, and can be erected in horizontal, inverse V, cable-stayed or even vertical ways. The resonant frequency can be flexibly changed in the range of 5-50MHz by rolling the irradiator on the reel. In addition, 9 amateur radio bands 5/7/10/14/18/21/24/28(29)/50MHz are marked as resonance points on the irradiator to facilitate fast and accurate switching of working frequencies.