Jun Fan

Bio: Jun Fan is an academic researcher from Missouri University of Science and Technology. The author has contributed to research in topics: Equivalent circuit & Printed circuit board. The author has an hindex of 36, co-authored 482 publications receiving 5641 citations. Previous affiliations of Jun Fan include Ulsan National Institute of Science and Technology & University of Missouri.

Studying the effects of location offset on the evaluation of MIMO performance based on the radiated two-stage (RTS) method

Abstract: The intermediate results in Stage I of the RTS method can be used to help evaluate the quality of the designed MIMO antennas, which can benefit engineers with the debugging process for MIMO systems. This is achieved by exploiting the obtained intermediate results to calculate some metrics including envelope correlation coefficient (ECC) and antenna gain imbalance (AGI). The detailed process is described in the paper. The performance evaluation is desired to be accurate. However, the user equipment (UE) location offset may exist during real measurements and this can affect the evaluation of the MIMO performance. Thus, it is of interest to study to what extent the MIMO performance evaluation is influenced by the UE location offset.

Differential probe characterization

Abstract: In this paper, a novel probe without ground pins is proposed for differential signal measurement. An effective model for the differential probe is built in CST based on measured dimensions. To evaluate the electrical performance of the differential probe, a 4-port measurement is performed for a 1 inch differential pair using the probes. Simulation and measurement results match closely which further verifies the accuracy of the simulation model of both the differential probe and PCB under test. Guidance for launching footprint optimization of the differential probe can be extracted based on the sensitivity analysis results in terms of signal pad size, ground via size and ground pad size of the differential probes. Furthermore, loop inductance of the differential probe is evaluated from both 1-port measurement and simulation results.

Modeling connector contact condition using a contact failure model with equivalent inductance

Abstract: It is found from previous studies on the immunity issues of CATV coaxial cables due to contact failure that, when contact resistance is small, the contact distribution and the number of contact points become factors that affect the degradation in immunity of the cables. However, when contact resistance is relatively large, the effects of the contact distribution and the number of contact points are negligible. In this paper, the physics of this phenomenon is further studied. Simulation results, validated by measurement, reveal that the contact distribution and the number of contact points contribute to parasitic inductances that could change the current distribution among the contact points, and further affect the immunity performance of the cables. Using a contact failure model proposed in this paper, cable contact scenarios at the connectors with different contact distributions and numbers of contact points can be simply simulated by changing the inductance term in the model.

Improved Transmitter Jitter Modeling for Accurate Bit Error Rate (BER) Eye Contours Using Transient Simulation of Short Bit Patterns

Abstract: Increase in the signaling speeds has led to decrease in jitter budget available for the channel to pass the product specifications. The current serial link specifications are based on a bit-error-rate (BER) metric and hence there is a need to account for jitter statistically. Accurately capturing jitter through the channel is very important to have confidence in the product specifications. Current statistical eye approaches are based on either single pulse/step response or multiple edge responses, which do not account for transmitter (Tx) driver jitter accurately since jitter interaction between the edges is ignored. There is an inherent assumption in pulse/step response methods that there is zero correlation between independent responses created from 2n combinations for n cursor pulse response where n is number where the tail settles, hence one zero crossing does not impact an adjacent zero crossing. Transient simulation accurately accounts for Tx jitter but is time consuming and requires large memory when simulating very large bit sequences. A new methodology is proposed to generate BER contours that capture the Tx driver jitter and inter symbol interference (ISI) through the channel accurately using unique waveforms created from truth table bit combinations. It utilizes 2N short N bit patterns as waveforms with jitter correlation from current bit patterns into adjacent bit patterns to get equivalent transient simulation of a desired pseudo random bit sequence. The method accounts for the edge interactions from any current bit pattern to next successive bit pattern to account for ISI accurately. The statistical eye diagram generated with the above approach includes nonideal channel characteristics, including ISI, XTK from nearby aggressor channels, and jitter through the channel.

Accurate RFI prediction of 3D non-planar connector with half magnetic dipole pattern

Abstract: In this paper, a dipole-moment based reciprocity method is applied to a consumer electronic device. The dipole moment is then used to predict radio-frequency interference (RFI) from a high-speed connector to two nearby RF antennas. The connector has a 3D structure with data pins verticallyoriented, for which the near H field pattern around the connector shows a half magnetic dipole pattern. This is different from typical complete dipole patterns over planar printed PCB (printed circuit board) structures. To tackle this problem, a magnetic dipole is placed in full-wave simulation with a similar connector structure. Using the reference near field data from simulation an equivalent magnetic dipole moment for the measured field is obtained. Further reciprocity theorem is applied to predict RFI based on the equivalent dipole magnitude and the antenna reverse H field. The predicted RFI shows a fairly good match with the measured RFI for both victim antennas.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

IEEE Transactions on Microwave Theory and Techniques and Antennas and Propagation Announce a Joint Special Issue on Ultra-Wideband (UWB) Technology

Abstract: Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.