An improved design of harmonic suppression for microstrip patch antennas

Harmonic suppression is an important factor for active microstrip patch antennas radiating harmonic frequencies. Here, a novel compact low pass filter (LPF) having high filter selectivity and wide stop band is used on the microstrip feed line of the patch antenna. The 15 dB LPF stopband exist over 10 GHz while implementing area is 0.1464λ_g × 0.1789λ_g at the cutoff frequency of 3.55 GHz. The fundamental antenna operating frequency falls in the passband of the LPF. The other harmonics falls in the LPF stopband and thus attenuated. An example shows up to fourth harmonic are suppressed while total occupying area remains compact. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 103–105, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22049