Harmonic suppression with spur-line for microstrip patch antenna

A microstrip patch antenna with a spur-line is proposed in this paper. It is demonstrated that the application of spur-line suppresses the high order harmonic TM₀₂₀ and TM₀₀₂ by 3 dB and 10.5 dB, respectively. And the return loss level of the dominant mode TM₀₁₀ is improved by 5 dB. Moreover, the spur-line is etched in the feed line without increasing the size of the antenna system. Finally, this compact antenna was designed, fabricated and measured. The experimental results of the antenna have a good agreement with the simulated results.