Analysis of monopoles installed on airframes

The determination of the radiation patterns of antennas installed on airframes is not always an easy task. Patterns can be measured by performing in-flight tests, which are very expensive and allow the determination of only few cuts. Another limitation is that only few samples are obtained (in general, at every 10°). An alternative is down scaling all the dimensions of the aircraft and of the antenna, and scaling up the measurement frequency. In this case, a scaled model of the antenna is necessary and mock-ups of the aircraft can be used. These are some of the topics being studied in the IPAS (Installed Performance of Antennas on Aerostructures) project. As a partial result of the investigations, this paper presents the analysis of monopoles installed on airframes considering the use of different techniques and different discretization criteria. Antennas operating at 126 MHz and at 1 GHz (full scale) are analyzed and the results compared with radiation patterns measured using a 1/12th scaled mock up. Despite the simplicity of the radiators, the results obtained in this study are important to serve as guidelines for the analysis of more complex antennas on airframes.