The work presented in this thesis is on the development of reliable low cost measurement systems for measuring microwave and millimetre-wave devices. The purpose of this work is to find techniques which use multiple power detectors and can measure magnitude and phase without the need for expensive superheterodyne receivers. Two novel microwave measurement systems have been designed with the intention of providing a measurement facility which enables the characterisation of both active and passive devices in terms of their scattering parameters. The first method is based on using a multistate reflectometer, which uses dielectric waveguide in the frequency range of 110GHz up to 170GHz. The dielectric multistate reflectometer is a four-port reflectometer, which uses a programmable phase shifter to give a flat relative phase shift over the entire frequency range of the dielectric waveguides used in the multistate reflectometer. The phase shifter has an eccentric rotating cylinder with an offset axis to allow a number of different phase shifts to the wave travelling in the dielectric waveguides in the multistate reflectometer. This system has been developed as an equivalent to a one-port network analyser. The second method is based on using the multi-probe reflectometer in which the standing wave in a line is measured using a number of fixed detector probes. A microstrip line prototype in the frequency range of 1GHz to 5.5GHz has been demonstrated and the design of a monolithic microwave integrated circuit (MMIC) version for the frequency range of 40GHz to 325GHz has been earned out. Improved methods of calibration of the system have been derived as well as different methods for error correction. The realisation of a full two-port network analyser using the technique has been demonstrated. Key words: dielectric multistate reflectometer, programmable phase shifter, multi-probe reflectometer, detection, microwave measurement, millimetre-wave measurement, calibration, error corrections.