Complete Characterization of Novel MHMICs for V-Band Communication Systems

This paper presents the characterization results of several new passive millimeter wave circuits integrated on very thin ceramic substrate. The work is focused on the design and characterization of a novel rounded Wilkinson power divider, a 90° hybrid coupler, a rat-race coupler, and a novel six-port (multiport) circuit. Measurements show the wideband characteristics, allowing therefore their use for multi-Gb/s V-band wireless communication systems. 1. Introduction The use of the 60-GHz band has attracted a great deal of interest over the last few decades, especially for its use in future compact transceivers dedicated to high-speed wireless applications in indoor environments (57–64？GHz) [1–3]. In this context, intensive research has been done to further develop new millimeter wave components for high data rate wireless communications according to the IEEE 802.15.3c standard. As previously demonstrated, the six-port technology offers an excellent alternative to conventional receiver architectures, especially at millimeter wave frequencies [4–6]. Nowadays, there are few promising high-quality fabrication technologies, yielding potentially low-cost millimeter wave components, such as the monolithic microwave integrated Circuit (MMIC) on GaAs or SiGe for large-scale production, and the miniature hybrid microwave integrated circuit (MHMIC) technology on very thin ceramic substrates, for small-scale production and prototyping [7, 8]. Moreover, several technologies have been intensively used for the millimeter wave circuit design and in-house prototype fabrication. We particularly note the coplanar, the substrate integrated waveguide (SIW), and the microstrip technology. The coplanar technology assures high-quality component design but is not well suited for low-cost production due to the difficulties in automating wire-bonding implementation, necessary for obtaining repeatable performances. On the other hand, the SIW technology assures high-quality component design on thin ceramics [9] or the design of optimal transitions from planar to standard rectangular waveguides [10]. For further circuit miniaturization, the microstrip technology on very thin, high relative permittivity substrate is recommended. As known, the microstrip line width is related to the characteristic impedance, substrate relative permittivity, and its thickness. It is to be noted that, due to reduced guided wavelength in high permittivity ceramic substrates, in order to keep the required circuit aspect ratio (guided wavelength versus the line width), the substrate must be as thin as