Research And Design Of Several Harmonic Suppression Antennas

The rapid advance of integrated circuits are led by the booming of semiconductor manufacturing technology. In order to meet demand from low to high frequency, microwave integrated circuits emerged. The attendant problem is that the power added efficiency has to be maximized when size and complexity of circuits are not changed. Although the application of active antenna can be a good solution to this problem, the harmonic suppression circuit is still necessary, in case of damaging the entire system. At first, the conventional way to solve this is to add a filter between Active Integrated Antenna and its connective circuit, but it will bring other issues such as increasing circuit complexity, rising cost and so on. Using Harmonic Suppression Antenna avoids these defects, for this point, Dalian Maritime University Microwave Research Institution is commissioned to do the appropriate research content by Liaoning Putian Digital Co., Ltd.In this paper, three kinds of Harmonic Suppression Antenna are researched and designed, which are Defected Ground Structure, Coplanar Waveguide Feeding Structure and Circularly Polarized Structure.(1)Defected Ground Structure Harmonic Suppression Antenna:operation frequency is2.45GHz.There are two relatively smaller rectangles etched on the ground plane. The3rd harmonic is suppressed by tuning relative position and size scale of two smaller rectangles.Simulation results show, the return loss of3rd harmonic is more than-1dB, fundamental frequency is less than-15dB, gain of antenna is1.3dB. Measured results of parameters above are, more than-2dB,-16dB and1.2dB respectively.(2)Harmonic Suppression Antenna fed by Coplanar Waveguide:working at2.45GHz, the2nd harmonic frequency is suppressed by adjusting length of T-match loop, and the3rd harmonic suppression is accomplished by dumbbell Defected Ground Structure. From the simulated results, return loss of2nd and3rd harmonic frequency are both over-2dB, fundamental frequency is below-15dB, gain of antenna is1.3dB.All three parameters measured results are, more than-2dB,-15dB and3.05dB respectively.(3)Circularly Polarized Harmonic Suppression Antenna:1.575GHz is its operating frequency. Circular Polarization is achieved by triangle cut and coaxially feeding. To suppress the harmonic frequencies, the symmetrical slot is etched around the coaxially fed location on the radiation patch. Tuning the length and size of slot can changed its equivalent inductance and capacitance values of it. And this change affects resonant frequency of slot, in order to achieve the purpose of harmonic control. After Simulating, harmonic frequency’s return loss are all above-1.5dB, fundamental frequency is less than-15dB.Axial Ratio is below3dB in the range of1.572GHz-1.577GHz. Gain of antenna is7.37dB.Measured results of mentioned parameters above are, high harmonic frequency return loss is over-1.5dB, fundamental is-15dB, Axial Ratio is less than3dB at1.575GHz, antenna gain is6.12dB.Beyond that, some other important parameters of the three antennas above are analyzed deeply.