Magnus Hoijer

Including Directivity in Reverberation Chamber Radiated Susceptibility Testing

The susceptibility of electronic equipment against electromagnetic irradiation depends on irradiation direction and polarisation. We show how this dependency can be taken into account when performing a radiated susceptibility test in the reverberation chamber. In the reverberation chamber the stress onto the equipment under test increases with the number of independent stirrer positions in the same manner as, in open space the stress onto the equipment under test increases with the number of independent irradiation directions and polarisations.

Maximum Radiated Power Density From Electrically Large Sources—Comparing Probability Theory and Measurements

The unintentionally radiated power density from electrically large electronic equipment shows a strong directional dependence. The polarization of the emitted field is also a priori unknown. Time and economy makes it prohibitive to measure all orientations of the equipment. A simple probability model has been proposed to quantify the magnitude of the effect: the power received by a measurement antenna is exponentially distributed. We verify that simple model by measurements.

Field Statistics in Nested Reverberation Chambers

The electric field in nested reverberation chambers is Rayleigh distributed. Positioning an antenna in each of two nested reverberation chambers, the transmission amplitude coefficient between the two antennas is double Rayleigh distributed.

Comparison of Different Definitions of Field Strength Used in Reverberation Chamber Standards

In different standards involving reverberation chambers, the field strength is defined either using the magnitude of the vector (total) electric field, or the magnitude of a Cartesian (rectilinear) field component. We compare these methods for determining the maximum field strength. The ratio of the maximum of the total field to the maximum of a Cartesian component is a random variable whose probability distribution and statistics are derived and investigated. The mean value of this ratio is compared with the ratio of the respective mean values. Its standard deviation enables the estimation of confidence levels when comparing or converting between single measurements of the maximum total and maximum rectangular field Theoretical results are illustrated and compared with measured results obtained in four different reverberation chambers.

Fast and accurate radiated susceptibility testing by using the reverberation chamber

The reverberation chamber is a good tool to perform high level radiated susceptibility testing. The accuracy and repeatability is good, and the testing time is short. However, the susceptibility of electronic equipment depends on from which direction the equipment is irradiated. It has generally been assumed that the effect can not be included when performing a radiated susceptibility test in the reverberation chamber. In this paper we show the opposite, that it actually can be included.

Question to the Authors of “HIRF Penetration Into Simplified Fuselage Using a Reverberation Chamber Approach”

In a recently presented paper, a good statistical practical method to define and measure the high-intensity radiated field (HIRF) penetration into a fuselage was studied. We ask the authors of the paper whether the disagreement between theory and measurements, at the lower frequencies, is due to the fact that correlated measurement data was used

How we confused the comparison between high level radiated susceptibility measurements in the reverberation chamber and at the open area test site

We have compared a true high level radiated susceptibility measurement of a generic test object at an open area test site with a similar measurement in a reverberation chamber. The results show that the applied electro-magnetic field, necessary to disturb the electronics at the open area test site is the same as an equivalent electro-magnetic field derived from measurements in the reverberation chamber.

Polarization of the Electromagnetic Field Radiated From a Random Emitter and Its Coupling to a General Antenna

The polarization coupling between a random emitter and a measurement antenna is uniformly distributed between 0 and 1, independent of the receiving polarization of measurement antenna in use. The polarization efficiency when performing a radiated susceptibility test on the same object, is also uniformly distributed between 0 and 1.

Maximum levels inside an electromagnetic shielded cavity

We present analytic expressions to quickly calculate the maximum electric field and power levels inside an electromagnetic shielded cavity. Typical maximum values are 9–11 dB larger than the corresponding average values. The method is applicable to both worst case estimates in e.g. an avionics bay, as well as to calculate the test quantity when performing a radiated susceptibility test in the reverberation chamber.

Frequency resolved susceptibility testing as a substitute for angular resolved susceptibility testing

In commercial radiated susceptibility testing, only a few irradiation directions are used, making the risk of undertesting huge. We propose a model to reduce the undertesting without increasing the number of irradiation directions. The method uses frequency resolved radiated susceptibility testing as a substitute for the angular resolved radiated susceptibility testing. We have experimentally tested the model on different test objects, and it generally works, but fails within some limited frequency intervals, due to resonance peaks in the susceptibility of the equipment under test.