Passive intermodulation (PIM) in radio frequency (RF) pathways can arise from multiple factors, including the passive nonlinear effects inherent in coaxial connectors. This study develops models to characterize PIM behaviors under both ideal and nonideal contact conditions, specifically addressing the scenarios of oblique and shallow insertions. Finite element analysis (FEA) was employed to construct models that assess the current density distribution at the contact interfaces, considering both transverse and axial cross sections of the central conductors. In the transverse cross section, the contact radius is determined by the applied pressure, whereas in the axial cross section, the contact length correlates with the insertion depth. A PIM model was derived based on the peak current density at a localized contact area (a-spot). Customized connector samples were utilized for PIM testing. The consistency between predictions and measurements, confirmed through repeated insertions and withdrawals, substantiates the instability of PIM arising from nonideal connections within the connectors.

Electrical contact degradation will affect the signal integrity resulting in poor communication performance. In the present work, the effect of electrical contact degradation on wide-band digital signal integrity was studied using both the theoretical analysis and experimental testing. The characteristics of digital signals with rise times of 200ps, 400ps, 600ps and 800ps through connectors with different degradation levels were studied. The maximum bandwidth of these signals can reach up to 1.75GHz. An equivalent model of the connector with degraded contact surface was developed and the experimental results are consistent with the model results approximately. The influence of capacitance characteristics caused by degraded contact surface on digital signal waveform was calculated and analyzed. The results of this paper are helpful in developing a better understanding of the characteristics of wide-band digital signal waveforms through the degraded contact surface and provide a theoretical support to identify failure features in fault diagnosis.

Ball grid arrays provide a small size and high-density package, which may lead to crosstalk in complex working environments. Of specific interest in this current work, the impact of failed ground solder balls on crosstalk in microwave circuits using ground-signal-ground structure was evaluated by simulations and measurements. In the 3-D electromagnetic model, two single-ended signal transmission channels were developed to analyze the effects of failed solder balls and the distance between two soldering areas on the signal transmission performance and crosstalk. Based on the frequency distribution of resonance points and structural characteristics of the soldering area with failed ground solder balls, an inductive coupling model was proposed to quantify the impact of above-mentioned factors on signal crosstalk. The results obtained from 3-D electromagnetic and equivalent circuit models are in good agreements. Experimental tests were then conducted to verify the simulation results.

Millimetre wave (mmWave) has great potential in vehicle‐to‐vehicle (V2V) communication to provide wide bandwidth and low latency. However, the biggest challenge for the use of mmWave is the high propagation path loss and susceptibility to blockage among vehicles, especially in urban streets. Vehicle shadow fading is quite common in the actual V2V communication. The non‐line‐of‐sight scenarios are considered and the impacts of blocking vehicles on the characteristics of the V2V wireless channels are studied. The measurements are conducted for two scenarios. For the first scenario, a blocking truck is placed between transmitting and receiving cars. For the second scenario, a car is added as a reflector beside the truck. Based on the measurement results, a path loss model for the V2V communication is developed. In order to further verify the effects of building scattering, a simulation is setup and the results are consistent with the measured results.