Mirrored aperture synthesis (MAS) has been proposed as a novel interferometry to achieve higher spatial resolution in passive microwave remote sensing. The phase and amplitude errors for MAS are a crucial problem that has yet to be analyzed. In this letter, a model for the phase and amplitude errors is established. A correction method based on an external source is proposed to correct the phase and amplitude errors. An analysis of the position of the external source is performed by computing its impact on the radiometric accuracy of a reference scene. The imaginary parts of the cross correlations for MAS are analyzed for the first time. Simulations and experiments are carried out to demonstrate the effectiveness of the correction method.

This article presents a defect detection method for diagnosing pseudo soldering problems in radio frequency (RF) circuit components. The algorithm integrates the source reconstruction method with the difference method (DM-SRM) to reconstruct the source distribution pinpointing the defect location effectively. Initially, the algorithm utilizes the difference between the radiated fields of the intact device and the defective one as input for the SRM. Subsequently, leveraging prior information regarding the sparsity of defects, the algorithm utilizes elastic regularization to address the ill-conditioned problems inherent in the SRM, thereby enhancing its noise robustness. The proposed method’s effectiveness and robustness are demonstrated through simulations on patch antennas and measurements using a near-field system for a microstrip power divider and a low-noise amplifier (LNA).

Near-field probes have been widely used in the measurement of radio frequency circuits and integrated circuits. It is an important process to correct the output distribution of the probe to the field distribution. However, near-field probes generally have certain receiving characteristics, which determine their performance. Therefore, it is very important to calibrate the receiving characteristics of near-field probes. In this article, we present an efficient probe calibration and probe compensation technique for electromagnetic near-field scanning. In the probe calibration process, the alternating direction method of multipliers is applied to flexibly solve the deconvolution problem, which facilitates reducing computational complexity in the spectral domain and elastic-net regularization in the spatial domain. For the probe compensation process, the second-order derivative constraint is introduced to improve the antinoise ability and the smoothness of the reconstructed results. Numerical examples and laboratory experiments show the effectiveness of the proposed method.

This paper presents a broadband near-field probe designed for measuring the normal magnetic field ($H_z$) in radio frequency (RF) circuits operating within a frequency range of 2–8 GHz. The proposed probe uses a cost-effective 4-layer printed circuit board (PCB) structure made with an FR-4 substrate. The probe primarily consists of an $H_z$ detection unit, a broadband microstrip balun, and a coaxial-like output. The broadband balun facilitates the conversion from differential to single-ended signals, thereby enhancing the probe’s common-mode rejection capability. This design ensures that the probe achieves both cost efficiency and high broadband measurement performance. Additionally, this work investigates the feasibility of employing microstrip lines as calibration standards for the $H_z$ probe. The probe’s structural parameters and magnetic field response were initially determined through simulations, and the calibration factor was subsequently verified by calibration experiments. In practical measurements, the field distributions above a microstrip line and a low-noise amplifier (LNA) were captured. The measured field distribution of the microstrip line was compared with simulation results to verify the probe’s performance. Meanwhile, the measured field distribution of the LNA was utilized to identify the radiating components within the amplifier.

The method of moments (MoM) for solving surface integral equations (SIEs) has been developed to simulate the electromagnetic (EM) scattering of uniaxial objects within uniaxial multilayers. Utilizing the uniaxial layered medium Green’s functions (LMGFs), the Poggio–Miller–Chang–Harrington–Wu–Tsai (PMCHWT) formulation is employed to derive equivalent electric and magnetic current densities in the scatterer, thereby determining the scattered field. A notable advancement in this work is the implementation of a singularity subtraction method for the uniaxial LMGFs, specifically designed to expedite the Sommerfeld integrals. This method effectively eliminates the singularity of Green’s functions in uniaxial multilayered media. Furthermore, our approach obviates the need to address the singularity associated with surface-wave poles and branch cuts in the Sommerfeld integrals. The primary contribution of this research lies in the development of MoM for analyzing uniaxial objects embedded in uniaxial multilayers, particularly when the optical axis of the scatterer is not aligned with that of the background. The accuracy and efficiency of our proposed method have been validated through several numerical experiments, with comparative analyses against results obtained using COMSOL Multiphysics.

In the near-field scanning technique, the near-field probe is the key sensor and the probe output is related to the probe receiving characteristics and the field distribution. Therefore, it is necessary to compensate the probe output distribution to the real field distribution based on the probe receiving characteristics. There are two main probe compensation methods: the spectral-domain method and the spatial-domain method. Due to the use of the 2-D Fourier transform algorithm, the spectral probe compensation method does not work well when the probe output spatial distribution is truncated while fields are not negligible. In this article, we present an enhanced spatial probe compensation technique for electromagnetic near-field scanning. This method enables the direct compensation of the truncated probe output, resulting in a more accurate field distribution. To overcome the poor constraint ability of traditional spatial probe compensation methods, electromagnetic constraints are introduced to transform the probe compensation problem into a source reconstruction problem. The effectiveness of the proposed method is verified by the numerical example and laboratory experiments.