The First Higher Mode Strip Transmission Line as a Loss-Reduced and Mass-Productive Printed Circuit at Millimeter-Wavelength

Futoshi KUROKI  Kazuya MIYAMOTO  Shigeo NISHIDA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E88-C   No.10   pp.1961-1967
Publication Date: 2005/10/01
Online ISSN: 
DOI: 10.1093/ietele/e88-c.10.1961
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Technologies on Devices, Circuits, and Systems for Millimeter-wave ITS Applications)
Category: 
Keyword: 
strip transmission lines,  guided waves,  reactance elements,  and millimeter-wave integrated circuits,  

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Summary: 
A higher mode tri-plate strip transmission line, in which the first higher mode propagates, was developed to realize mass production of millimeter-wave integrated circuits for application in intelligent transport systems, and its transmission characteristics were investigated. The design diagram of this guided mode was determined and a higher mode tri-plate strip transmission line was fabricated at 30 GHz. The dispersion curve was found to be similar to that of a rectangular waveguide and a low transmission loss of less than 10 dB/m was obtained. For construction of some functional devices, two types of basic reactance components, such as a gap and a slot, were expressed by equivalent circuits. The former was expressed by capacitive parameters, and the latter was expressed by an ideal transformer with inductive parameters. The gap-coupled circuit was successfully employed for a 3-pole 0.1 dB Chebyshev ripple band-pass filter with a small excess insertion loss of less than 1 dB at a center frequency of 32 GHz, as well as no spurious response in a bandwidth from 26.5 GHz to 40 GHz. The slot element acted as a matching circuit and a suppressor of the lowest mode, which is the TEM mode in the tri-plate strip transmission line. Moreover, this element was applied to a mode transformer between the lowest mode and the first higher mode.