Harmonic suppression in microstrip patch antenna using spur-line filter

This paper proposes a method for suppression of higher order harmonics in microstrip antenna using spur-line filter. The microstrip antenna is designed to operate at frequency 2.45 GHz. For the antenna input impedance design, it was used a combination of quarter-wavelength transformer and inset feed impedance matching technique. To suppress the second and third harmonics a spur-line filter was inserted in the antenna microstrip feed line. The measured and simulated results are presented for the proposed antenna. The analysis of the antenna radiation properties shows that beyond the accuracy of high order mode suppression, the insertion of spur-line filter does not any degradation into the radiation pattern.