This paper presents a method for measuring whole-body specific absorption rate (WBSAR) of millimeter-wave base stations (BSs) in a reverberation chamber (RC). The absorbed power in the phantom from the equipment under test (EUT) and hence WBSAR is determined as the difference between the total radiated power with and without the phantom. A chamber transfer function is determined and used to include only the absorption in the phantom due to direct illumination from the EUT, i.e., excluding absorption due to the RC multipath reflections. The measurement method was evaluated at 28 GHz using a horn antenna and a commercial massive multi-input–multi-output BS. The experimental results are in good agreement with simulations. The proposed method allows for measurements of WBSAR within 3 minutes, which is much shorter than traditional approaches. The method is suitable for compliance assessments of BS products with the International Commission on Non-Ionizing Radiation Protection 2020 electromagnetic field exposure guidelines, which extend the applicability of WBSAR as basic restrictions up to 300 GHz.

A flexible broadband antenna with high radiation efficiency for the Internet of Things (IoT) applications is presented. The design is based on a U-shaped and a triangular-shaped radiator with two tuning stubs. A 50 Ω coplanar waveguide (CPW) transmission line is employed to feed the antenna. The proposed antenna is fabricated on a flexible substrate from a composite synthesized by mixing natural rubber with SiO2 as a filler. The radiating elements, along with the CPW, are built using a highly conductive woven fabric. Results show that the antenna has a simulated and measured impedance bandwidth of 0.856–2.513 GHz and covers the most commonly used wireless communication standards and technologies for IoT applications. The radiation efficiency of the antenna reaches over 75% throughout the operating frequency band with satisfactory radiation patterns and gain. The flexible antenna was also tested under bending conditions. The presented results demonstrate that bending has a minor effect on the antenna performance within the target frequency range. The measured results show a good agreement with simulations.

Traditional near-field antenna measurements use the sampling theorem to reconstruct the antenna pattern perfectly. However, a large number of measurement points are required for this approach. To address this problem, in this study, we propose a technique to accelerate the near-field antenna measurement, which is achieved by sparse E-field sampling in the region where the E-field changes smoothly and dense sampling in the region where the field changes rapidly. Further, our approach ensures robustness of measurement; the E-field information need not be known before carrying out measurements. Our experimental results demonstrate that our technique can reduce the number of measuring points by at least 64.9% when measuring two different patterns (15-GHz horn antenna with θ = 0° and 10°).