A Circularly Polarized Harmonic-rejecting Antenna at 2.45ghz for Wireless Power Transfer

A novel compact proximity coupled microstrip antenna harmonic suppression with resonant at 2.45 GHz of rectenna application is presented in this paper using inexpensive FR4 substrate. An unbalanced slot has been fit on the radiating element to block the harmonic signals and achieve circularly polarized antenna. The evolution of the harmonic rejecting techniques began with a circular slot on the circular patch antenna followed by another circular slot positioned on the other side of radiating patch. Adequate suppressions of the second and third harmonics are obtained with minimum reflection coefficients up to greater than -3 dB respectively. The return loss of proposed design yields -29.16 dB at 2.45 GHz and offer high gain with 6.23 dB with bandwidth around 125 MHz. The proposed antenna also gives 24% size reduction compare with conventional circular patch. From the simulation result, the proposed antenna can be a good choice in the rectenna system for future wireless power transmission application.