Improved radio frequency imaging resolution using phase contrast interferometry

Phase contrast techniques offer notable enhancement in resolution when used in optical microscopy. Microwave frequencies offer a high degree of penetration but resolution is limited in comparison to traditional imaging techniques. Application of this principle to centimetre wavelength radio frequency imaging can provide significant improvement in system accuracy. Using standard vector network analysis phase and amplitude measurements, dimensional resolution better than 1 mm at a frequency of 5 GHz was obtained. Signal integrity is maintained over a distance of 1 km using a novel optical transmission system that utilises a Reflective Electro Absorption Modulator and directly modulated Vertical Cavity Surface Emitting Lasers.