A Tri-Band Patch Antenna With Dual Rampart Line Structure

A tri-band patch antenna with dual rampart line structure is presented. The proposed antenna consists of a rectangular patch, and a rampart line structure with stubs of optimized lengths. The rampart line structure is etched into a rectangular patch for achieving size reduction and arising a new mode. The
n
= 0 harmonic of the rampart line makes TM
₁₀₀
mode of the rectangular patch resonate at a lower frequency. And the
n
= −1 harmonic of periodic rampart line will introduce a new resonance frequency. Combining the above two frequency and TM
₀₁₀
mode, a triband antenna is designed and manufactured for the Chinese 5G working bands. The results of simulation and measurement show good agreement. The proposed antenna works at 3.56, 4.83, and 5.84 GHz. The electrical size of the patch is 0.22 λ
₀
× 0.20 λ
₀
× 0.023 λ
₀
, in which λ
₀
is the wavelength of the lowest frequency at 3.56 GHz. Experimental results show an excellent performance in terms of radiation patterns, gains, cross-polarization level, and front-to-back ratio over the operating bands.