Use of Microstrip Transmission Line to Improve Broadband Electromagnetic Measurements

As electronic components and systems are miniaturized, electromagnetic capability measurements are complicated by the requirement of making broadband probes and energy samplers sufficiently small in order to minimize parasitic impedances and mismatch. Use of microstrip transmission lines as couplers or adaptors to connect miniature components under test to standard coaxial broadband test equipment can provide considerably better control of impedance match than other transmission line configurations resulting in improved accuracy of measurement and convenience of use. A description of microstrip characteristics and fabrication procedures pertinent to this application is given. A novel microstrip device with a provision for inserting current probes, electroexplosive devices, magnetic cores and other miniature current-sensitive components has been built and tested. It can be used as a broadband coupler for measuring impedance and transient response to current inputs or as a calibrator to supply a predetermined current to a current-sensing probe from DC to 1.1 GHz with a maximum error of 2.7 dB. Other microstrip couplers designed for measurements on electroexplosive devices are also described.