Yihong Qi

Multiphysics Analysis of Millimeter-Wave Absorber with High-Power Handling Capability

For the fifth generation wireless communication system, millimeter-wave absorber has been frequently used in the measurement of high-power devices, such as transmitting antennas of base stations or satellite communication antennas, etc. The overheat inside the absorber can always be a matter of concern because it may lead to catastrophic fire in the anechoic chamber. A novel pyramidal structure with vent holes and heat sinks was proposed to improve the heat dissipation. The power-handling capability of the wave absorber could be improved by increasing the heat dissipation path without changing the characteristics of the base material. Multiphysics simulation was carried out to analyze the thermal-electromagnetic interaction. This absorber can be used to measure the high-power antenna and the radar system inside anechoic chambers, with power density up to 7 kW/m2.

Objective Total Isotropic Sensitivity Measurement

The characterization of the performance of wireless devices plays a significant role in developing radio products that meet the demands of the latest standards and deliver a satisfying user experience. With current standard total isotropic sensitivity (TIS) measurement, the transmitters are set to work at their maximum transmission power level. However, the standard TIS test procedure is unable to accurately reflect a receivers performance because in actual usage transmitters are rarely working at their maximum power level. In measurements, different kinds of devices hold different maximum power levels. The measured radio sensitivity depends on the instantaneous local temperature of the radio, and the local temperature depends on the heat generation (power levels), the heat dissipation, and time. So the power levels and the thermal conditions could affect their radio sensitivity and, hence, the TIS. With standard TIS methods, the maximum power level and the radios thermal condition cause ambiguity in the measurements. However, this paper proposes a new objective TIS method. With this new TIS method, the measured TIS is a function of the transmitter power level at its thermally stable condition. The proposed method resolves the ambiguity of the TIS measurement.