Band Rejection Methods for Planar Log-Periodic Antennas

Full-wave modeling and measurements are utilized to propose three band rejection techniques integrated with a multi- octave wideband planar log-periodic antenna. Antennas presented in this paper are designed to operate between 1.8 and 11 GHz with rejection at 6 GHz. Demonstrated band-rejection techniques include the removal of resonant teeth also referred to as aperture rejection, integration of a dual band filter, and combination of the two above techniques. Aperture rejection is shown to produce greater than 25 dB realized gain reduction. Integrated filter and combined methods achieve over 30 dB and 55 dB rejections, respectively. Antennas are fabricated on a 0.508 mm RT/Duroid 6002 substrate and excellent agreement between theory and measurements is obtained.