Wee Jin Koh

Evaluating field uniformity of a mini-reverberation chamber with two mechanical stirrers

The objective of the paper is to experimentally evaluate the field uniformity of the electromagnetic environment within a mini-reverberation chamber made of aluminum material and with two orthogonal and mechanical stirrers. The frequency spectrum of interest is between 8 GHz and 10 GHz in the step of 0.1 GHz. Sixty stirrer steps are made at each frequency within a complete stirrer rotation. A small dual-ridge horn antenna, designed at 8-10 GHz, is used as the transmit antenna, while another identical dual-ridge horn antenna is applied as the receive antenna to make field strength measurements continuously. The electric field strengths are measured at nine different locations within the chamber. The measured results suggest that the field uniformity of this mini-reverberation chamber is excellent by employing the proposal of the IEC 61000-4-21.

Introduction to reverberation chamber test method and a two-stirrer mini-reverberation chamber

As a time-efficient and cost-effective EMC test facility candidate, the reverberation chamber has attracted much attention from academia and industries. The objective of the paper is to introduce its general background, standardisation status and practical applications, highlighting some of merit and non-merit associated with the reverberation chamber test method. A mini-reverberation chamber made of aluminium with two orthogonal and mechanical stirrers is also presented.

Controlling the state of a reverberation chamber by means of a random multiple-antenna stirring

In this paper we introduce a novel technique based on the random excitation of several antennas. As opposed to previous attempts at this approach, the random signals are correlated by means of a pre-conditioning filter, in order to increase the number of accessible degrees of freedom and optimize the covariance matrix of the field measured in the chamber. A dramatic improvement is observed at those frequencies where standard mechanical stirrers fail.

Near-field to far-field prediction for high-speed board using an empirical approach

This paper describes a methodology to predict far-field (FF) emissions from a high-speed board based on the fields measured in the near-field (NF) region. The NF to FF transformation is based upon an empirical relationship between the measured fields in both the NF and FF regions. Initial results show that the predicted FF emissions from a high-speed board provide the designer a good confidence on the compliance of regulatory emission limits.

Evaluation of fibre weaving of substrate on differential striplines using an analytical approach

Electrically long differential signal traces may introduce significant signal skew due to weave effect that deteriorates the signal quality. As serial data link pushes towards higher data transfer rate and yet the length of the signal trace has not reduced, the weave effect will become significant. Full wave method is often used to study the weave effect, however, the computational time is expensive. As such, a novel analytical method is proposed in this paper to study the fibre weave effect in PCB dielectric.

Pre-layout multi-layer PDN model for high-speed board

A method on developing pre-layout PDN model utilizing 3D full-wave simulation was proposed in this work. The proposed method divides the PDN into different blocks and obtains the network parameters of each block using 3D full-wave simulation. The proposed method was validated with post-layout simulation. Results show that PDN impedance obtained from pre-layout PDN model developed using proposed method agrees well with post-layout simulation result.

Development of near-field emission limit from radiated-emission limit based on statistical approach

This paper discusses a novel approach to transforming a radiated-emission limit (e.g., CISPR 22 and FCC) from the far-field to the near-field region. The proposed approach combines data from a near-field scanner and a gigahertz transverse electromagnetic cell with statistics to establish a simple relationship between a near-field magnetic field and a far-field electric field. It is shown that the proposed approach has the potential to be a simple, quick, and fairly inexpensive tool for electromagnetic compatibility pre-compliance purposes.

Out-of-band gain prediction of blade antennas for EMC purpose

In this paper, the out-of-band characteristics of the airborne blade antennas are studied in terms of their gain and radiation properties. A prediction model was derived for both the lower out-of-band and upper out-of-band frequencies of a typical blade antenna.

Estimating frequency spectrum of IC power supply current through time-domain voltage measurement on power distribution network

A method to estimate the frequency spectrum of IC power supply by measuring transient voltage on Power Distribution Network (PDN) was proposed in this work. The proposed method was validated through measurement on a testing board with three clock driver ICs. The result show good agreement between the estimated current spectrum and measured current spectrum at the major spikes.

Out-of-band conducted susceptibility measurement and analysis of VHF/FM communication system

With proper frequency management, one can prevent in-band radio frequency interference (RFI). However, at out-of-band (OOB) frequencies, RFI is almost impossible to prevent. And such OOB interference characteristics of communication devices may not be provided by the supplier of the devices. In this paper, we present the results of OOB conducted susceptibility measurement for a VHF/FM communication system. Detailed analysis were given for several of the interference frequencies and lastly, the results were compared with Mil-Std 461C CS04 limit line.