Design and Simulation of Microstrip Antenna for Phased Array and Analyzing Nonlinear Effect of Amplifier on Array Pattern

Active integrated antennas are used especially for millimeter-wave scale systems, because these antennas are considered as effective solutions to the basic problems at these frequencies, which include higher levels of loss in the transmission line, limited power source, low antenna efficiency and a lack of having high-performance phase-switches. Moreover, increasing the effective length of small antennas, having higher antenna bandwidth, reducing the cross-link between array elements and improving noise number are some of the benefits of active antennas. One of the most important challenges that these confront which the requirement can be adequately optimized is the Carrier to Interference Ratio (C/I). These existing interferences are due to sub-petals, polarization, lateral channel and intermodulation interferences. In this research, the effects of nonlinearization of amplifiers on the phased-array pattern in microstrip antennas are investigated in elaborations. The most dangerous nonlinear effect in an active arrays of a multifactorial system is that the intermodulation components produced by the behavior of the nonlinear amplifier must be studied in advance. This phenomenon is most often occurring in active transmitter arrays. However, many of these results can also be used for receiver arrays. First, a transistor made by Motorola was selected, and then adaptation circuits for this transistor as well as microstrip antenna designed at ۲GHz, respectively added to the set, and an active ۹W transmitter antenna was designed. The designed amplifier was then analyzed nonlinearly and used to model the behavior of the transistor. Finally, different patterns of the array were examined and a ۱×۱۵ array was excited with a uniform distribution. Based on our results, the nonlinearity of the amplifier has little effect on the radiation pattern of the antenna. Even though, it creates a pattern of intermodulation components, the frequency-dependent Bessel series model should be used in the case of broadband antenna design.

کلیدواژه ها:

Microstrip Antenna ، Active Integrated Antennas ، Millimeter-Wave scale ، Phased Array ، Intermodulation ، Carrier to Interference Ratio (C/I)