Implementation Possibilities of Standard Site Method Sub-cases for EMC Antenna Calibrations in Non-ideal Site Conditions

Today, a number of engineering issues require electromagnetic compatibility (EMC) tests, in turn triggering the need for EMC-antenna calibrations. In this framework, experimenters seek accurate and time-saving solutions. Basically, standard site method (SSM) ANSI C63.5-2006 stipulates the near-to-ideal conditions on an empty and vast land, where three antennas are used for antenna factor determination. In our previous work, we investigated the suitability of narrow test sites for antenna calibration according to three-antenna SSM-ANSI-C63.5-2006, whose usability was validated under certain conditions. In the present study, we expand our research by applying the sub-cases of using a known antenna and identical antennas specified in the standard in order to shorten the calibration process. The results reveal that the methods for various calibrations are useful for successfully running the process even in non-ideal sites and help significantly reduce the experimentation time, considering the uncertainty limits specified in EMC test standards

Proposal of a Planar Directional UWB Antenna for Any Desired Operational Bandwidth

A novel planar directional UWB antenna is proposed. The antenna design evolves from an oblique elliptic cone antenna by applying the planar-solid correspondence to two axes. Through a simple equation, this antenna can be designed, to operate at a specific lower cutoff frequency with a bandwidth larger than 10 GHz for a reflection coefficient magnitude lower than −10 dB. This characteristic provides the antenna with a good versatility. The directional radiation pattern has an average gain of 6 dBi

Low-investment EMI pre-compliance for COTS technology insertion into submarine combat systems

A modern submarine’s combat system is largely dependent on commercial off the shelf (COTS) computer technology as a means of cheaply adopting the latest, high-performance, commercially developed and qualified systems to maintain capability. COTS technology is not normally designed for military use, nor is it necessarily compliant to military standards for electromagnetic interference (EMI), such as MIL-STD-461G. A gap analysis, based on a comparison of commercial and military EMI standards, showed that there is no guarantee of COTS EMI compliance to this military standard. Formal compliance testing at a certified test house is almost prohibitively expensive for purposes of early experimentation and component evaluation. This is due to the highly controlled, calibrated and specialist nature of such facilities. Because of this, they are normally only used for final compliance testing prior to acceptance of new designs into service. In order to reduce the risk of a compliance failure, pre-compliance testing should take place prior to and even during system design. Evidently, a need exists for a low-investment and practical test protocol to verify the EMI performance of such COTS equipment against the applicable military EMI standards. Background research was undertaken into the historical development of current commercial and military EMI standards, the trend and motivation for the use of COTS in the defence environment, as well as the mechanisms and theory of EMI design as applied to the submarine. This research was critical in the development of a gap analysis procedure as well as the development of low-cost and practical alternatives to formal EMI testing with simplified tests as pre-compliance test protocols

Small reverberation chambers for radio frequency emission measurements: a radio astronomy feasibility study

To use a Reverberation Chamber (RC) below the Lowest Usable Frequency, this thesis applies: multiple receiving antennas; multiple EUT positions; and a modified validation procedure. Emission measurements are then possible down to the first cavity resonance. The design is based on theory and simulations, and validated by on a prototype. The longer measurement times, compare to conventional RCs are acceptable where sensitivity is of concern, e.g. in radio astronomy or defence applications

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

Development of EMC antennas and their application in on-line SE measurement of conductive composite plastic materials

The development of three new EMC antennas, namely the V-conical-lens antenna (VCLA), half of a Transverse Electromagnetic-T (TEM-T) cell (acting as an antenna) and the Q-loop antenna (a quarter of a loop antenna in front of 90 ° comer reflector) is described. These antennas, when calibrated, are designed with a view to employing them in the measurement of on-line Shielding Effectiveness (SE) of conductive composite materials. Test devices incorporating those newly developed antennas for measuring SE against high impedance and low impedance wave are introduced. The theoretical model of the VCLA is developed and design features are presented as a state-of-the-art project with a view to developing this technique in the near future for measuring the plane wave SE of conductive plastics during their production process. A modified TEM-T cell designed to simulate a high impedance field on the material under test (MUT) in its (TEM-T cell's) near field region is presented. The field simulated by this device in the test location is studied theoretically. The device measures the high impedance field SE o f planar sheet-like conductive plastic materials in a situation that attempts to reconstruct the on-line environment likely to prevail in the manufacture o f such plastics. This test device is calibrated by taking into account the background noise, indirect path signal infringement and radiation losses. The newly developed Q-loop antenna is designed to be used to measure the low impedance field SE of conductive plastic materials. An analytical model of the Q-loop antenna is developed using image theory and the theory of pattern multiplication. This model is verified experimentally. Calibration experiments are performed to facilitate applying the antenna in an on-line SE measurement technique. A new class of filled composite material with a two dimensional regular array of conductive flakes (like a Frequency Sensitive Surface (FSS)) in plastic resin is proposed. A theoretical model of the suggested configuration is formulated and used to predict SE values. The SE of such material is also determined experimentally and compared with the theoretical predictions. This SE is compared with the SE o f an available filled composite in which the flakes are randomly distributed. The improvement in the shielding capability of the new class of material is highlighted. Relative radiation patterns of the developed antennas are measured and compared with predictions. Apart from the anomalies which can be attributed to (simplifying) assumptions made in the development of the theoretical analysis, the measured radiation patterns and other antenna parameters are in good agreement with predictions

Research reports: 1985 NASA/ASEE Summer Faculty Fellowship Program

A compilation of 40 technical reports on research conducted by participants in the 1985 NASA/ASEE Summer Faculty Fellowship Program at Marshall Space Flight Center (MSFC) is given. Weibull density functions, reliability analysis, directional solidification, space stations, jet stream, fracture mechanics, composite materials, orbital maneuvering vehicles, stellar winds and gamma ray bursts are among the topics discussed