Research On Microstrip Antenna Based On Capacitive Loading Technology

Microstrip antenna has many advantages such as small size, low profile, light weight, easy fabrication and so on. So microstrip antenna has been widely used in many fields. However, the resonant characteristics of high quality factor for microstrip antenna determine that the bandwidth of the antenna is narrow. Capacitance is an important part of the circuit, which plays an important role in the design of the circuit and the device. With the maturity of the chip capacitor technology, chip capacitors have characteristics of chip, miniaturization and high frequency. The design of microwave devices using chip capacitors has become the trend of development. Therefore, it is necessary to study the effect of chip capacitors on the performance of antennas.Firstly, this paper study the implementation of multi-frequency and broadband using chip capacitors. Characteristics of microstrip antenna using coplanar parasitic patch is introduced, and on this basis, two kinds of broadband antennas are designed by using slotted and parasitic patch, and the bandwidth of the two antennas is more than 200 MHz, which is 3-4 times of the ordinary rectangular microstrip antenna.Then chip capacitors is loaded on the gap between the main radiation patch and the parasitic patch. The effect of different capacitance value, position, quantity on the performance of the antenna is analyzed in detail. Then two antennas is designed. One is broadband antenna using chip capacitors, the bandwidth of 120 MHz is 2 times more than that of common rectangular microstrip antenna. Another is dual band tunable antenna using chip capacitors, High frequency resonance on the 2.48 GHz, while the low frequency can adjust between 1.74GHz~2.18 GHz when adjusting the value of capacitors.Secondly, this paper study the implementation of miniaturization using chip capacitors. The capacitor is loaded between the radiating edge of the microstrip antenna and the metal ground. The effect of different capacitance value, position, quantity on the performance of the antenna is analyzed in detail. Then two antennas is designed. One is miniaturized antenna using chip capacitors, the antenna size is reduced by 35.9% compared to the rectangular microstrip antenna. Another is miniaturized broadband antenna, compared with rectangular microstrip antenna, the antenna size is reduced by 16.3% and the bandwidth is increased by 56.6%.At last, the design of microstrip antennas were all produced and tested in this paper, the outconmes of test and simulation were compared and analyzed concretely.