Passive harmonic generation at spring contacts

In the first paper, the RF passive harmonic generation phenomenon on the spring contact is studied. A spring contact harmonic generation measurement system is developed. The factors that may have an impact on the spring contact harmonic generation, such as contact material, contact force, and contact resistance are characterized by the measurement system. The gold-to-gold contact is found to be much superior to the stainless-steel contacts. It is also found that the passive nonlinearity at the spring contact is the semiconductor-like junction formed by the surface oxide film. In the second paper, we show that the maximum E-field coupling occurs at a location slightly offset from the trace center. The E-field coupling to a shielded H-field probe at such a position leads to differential mode coupling which the standard shield of an H-field probe is unable to suppress. The coupling mechanism is investigated and a differential E-field coupling suppression approach is proposed. In the third paper, a measurement system which uses acoustic vibration to locate passive intermodulation (PIM) sources in base station antennas is presented. This measurement system uses mechanical vibration to modulate the PIM signal. By introducing the acoustic vibration at different locations in the base station antenna and observing if the PIM signal is modulated by the acoustic frequency, the most likely location of the PIM source is identified --Abstract, page iv

The field coupling mechanism study for near field probe

In this part, the radius of the loop is used to predict the voltage induced by the E- field in the circular loop antenna. The thin rectangle loop and thick rectangle loop have been investigated. The equivalent radius of the rectangle loop is estimated by the average of the one over the distance between the points on the loop to the center of the loop. The estimation matches with the numerical simulation --Abstract, page iv

Differential E-Field Coupling to Shielded H-Field Probe in Near-Field Measurements and a Suppression Approach

In near-field scanning using H-field probes, E-field coupling is a major concern. E-field suppression performance must be characterized before an H-field probe can be used for near-field scanning. Common method of measurement involves measuring the E-field coupling in the same location where the strongest H-field coupling occurs. In microstrip line traces, it is assumed that this occurs right above the center of the trace and less coupling at all other locations across the microstrip line. In this paper, we show that the maximum E-field coupling occurs at a location slightly offset from the trace center. The E-field coupling to a shielded H-field probe at such a position leads to differential-mode coupling, which the standard shield of an H-field probe is unable to suppress. The coupling mechanism is investigated and a differential E-field coupling suppression approach is proposed. For the H-field probe used in this paper, a proposed floating plate is shown to improve the measured E-field suppression ratio by a factor of 18 dB compared to a similar probe without this modification