Miniaturisation in E-Plane Technology
In a simple and cheap way, a planar full-band matching technique allows for miniaturisation of E-plane components. such as corners. shifts. T junctions. Magic Tees. cross-over and quadrature directional couplers a.o. A finline taper has been made half the length of the shortest computer optimized one, having similar performance. A transition to suspended stripline offers possibilities for this line instead of the finline. Although realised for X-band, scaling down to mm waves is our aim as well as application for devices. Additional technical details will be given at the oral presentation.
Synthesis of Optimum Finline Tapers Using Dispersion Formulas for Arbitrary Slot Widths and Locations
The theory of TEM matching sections has been modified so that it can be applied to finline tapers. A step-by-step procedure is given to calculate the taper contour for a given maximum VSWR. The taper is optimum in the sense that its length is the shortest possible for the required VSWR. To achieve fast convergence, a transversal resonance method was developed to calculate finline dispersion, which is valid for arbitrary slot widths and slot locations. The finline can be unilateral as well as bilateral, and the slot may be off-centered. The dispersion data are compared with values found in the literature, and the calculated taper performance with the authors' own measurements, both showing good agreement.
Planar GaAs Mott Low Noise mm-Wave (35 and 85 GHz) Mixer Diodes
Conversion losses of 5.0 dB have been achieved at 35 GHz, with SSB noise figures of 6 dB (including 1 dB IF) using coplanar Mott diodes in finline balanced mixers. [l] The variation of noise figure with local oscillator power is significantly less than for conventional Schottky diodes, and results from the voltage independence of the capacitance of Mott diodes [2]. The series resistance of these diodes is about 4¿, with a total capacitance of .05 pF. Smaller diodes, with capacitances of .03 pF, have been evaluated in 85 GHz balanced mixers. Conversion losses as low as 6.5 dB have been observed at 85 GHz, with improved operation over a wide range of local oscillator power, and further improvements are expected as devices and circuits are optimised at this frequency. In addition to achieving high performance the coplanar Mott diodes are made by low cost planar processing and are rugged.