F. Vitulli

The electric-field Integral-equation method for the analysis and design of a class of rectangular cavity filters loaded by dielectric and metallic cylindrical pucks

Rectangular cavity filters loaded by metallic and dielectric cylindrical pucks represent a wide class of structures used for the realization of compact microwave filters for space and terrestrial communications. The electric-field integral-equation method has been applied here to develop a software tool for the design of such a class of filters. Resonators simultaneously containing a number of dielectric and metallic cylindrical pucks can be analyzed using the method presented here. Dielectric loaded rectangular waveguide filters and comb-line filters are two typical examples where this approach can be applied. The input and inter-cavity couplings realized by slots have been modeled using the proposed integral-equation method. The full-wave analysis and optimization of an entire filter can be performed using the software presented here. Dielectric and metallic losses have been taken into account and the tuning screws have been also included into the analysis. The prototype of a single resonator and complete passband dielectric loaded rectangular waveguide filter have been realized and measured to test the software, and a commercial software has also been used to validate the code. A number of examples are presented here. A very short computation time of the order of 1-s/frequency point for the analysis of an entire filter has been obtained, making the full-wave optimization of an entire filter an affordable task.

A new multiple-tuned six-port Riblet-type directional coupler in rectangular waveguide

Directional couplers are fundamental components for the realization of power splitting and combining networks. A basic component is the four-port coupler realized in a wide range of different electrical and geometrical configurations. Using multiport directional couplers, with six or more ports, compact power splitting and combining networks can be designed. Most of the multiport directional couplers in a rectangular waveguide found in literature use an E-plane branch-line layout. A special configuration of a six-port narrow-wall short-slot directional coupler (Riblet type) is presented here. The coupler has only one central coupling region, following the Riblet concept based on the differences among the propagation constants of the modes through the coupling region. A number of different solutions have been investigated and some examples are presented here. Moreover, a multituning realized by using input resonators permits one to significantly enlarge the bandwidth. A six-port coupler equally splitting on the output ports the power injected at each input port has been designed for a 8.4% working band. The theoretical and measured responses presented here prove the effectiveness of the multituning concept.

RF-MEMS SPDT switch on silicon substrate for space applications

The paper illustrates the activity carried out under an ESA contract for the development of a miniaturized RF-MEMS SPDT switch and switch matrix using micromachining technology on a silicon substrate for power applications. A manufacturing procedure, based on an eight masks process, has been set up. At present, a broadband single-pole-double-throw (SPDT) switch operating in the 0-30 GHz frequency range has been fabricated and measured. Isolation of about -40 dB and insertion loss better than -0.7 dB have been obtained.

Compact Tuning Circuit for Enhanced Linearity in a Ku-Band MMIC VCO

This work describes a compact, tunable linearization circuit able to provide enhanced linearity characteristics and low sensitivity of the VCO output signal, also regarding temperature variation between -30°C and +70°C. The proposed solution is applied to the design of a Ku-Band MMIC voltage-controlled oscillator in push-push configuration. The chip has been realized by UMS Foundry in HBT technology with the HB20M process. The measured oscillation bandwidth spans from 10.52 to 12.53 GHz with a tuning range of about the 16%; sensitivity has an average value of 200 MHz/V, while the phase noise at 100 kHz of frequency offset from the carrier at 11.7 GHz is -98.5 dBc/Hz.

An MMIC beam forming network assembly for data relay satellite applications

An analog Beam Forming Network Assembly that is part of a Receiving Phased Array Antenna for the European Data Relay Payload is described. In such Beam Forming Network, the electronic steering is achieved by means of fully integrated Monolithic Microwave Integrated Circuit (MMIC) Phase Shifters. A detailed description of the assembly design is given in the paper and experimental results are discussed.