Out-of-Band Characteristics of the Microstrip Antenna

Abstract

The development of wireless communication systems is accompanied by both the development of new frequency ranges and the simultaneous use of one band of frequencies by several radio services. This fact leads to an increase in the number of noise and the deterioration of the electromagnetic environment. The level of electromagnetic interference at the input of the receiver depends to a large extent on the spatial characteristics of the antennas, such as the directional diagram and the magnitude of the gain in a particular direction. For the efficient operation of wireless communication systems, it is necessary to ensure the electromagnetic compatibility of radio electronic devices. In the case of radio systems operating at different frequencies, or if there are out-of-band and unwanted radiation, the electromagnetic environment assessment process is considerably more complicated. The main characteristics of the antennas, such as the radiation pattern, gain, input impedance, polarization, and others, are often indicated only for the operating frequency range, while the characteristics outside operating range are unknown. Therefore, it is relevant to study the frequency characteristics of antennas outside the operating frequency range. The main electrodynamic characteristics of a rectangular microstrip antenna outside operating frequency range are considered. The results are obtained by the numerical simulation, based on the method of moments in the frequency domain. The calculated frequency dependencies of the directivity and the gain factor taking into account out-of-band properties of the impedance at the antenna input make it possible to more accurately take into account levels of the electromagnetic interference and thereby ensuring the electromagnetic compatibility of the radio electronic means.