300-GHz Microstrip-to-Waveguide Transition on a Polyimide Substrate Integrated with an LTCC Substrate Integrated Waveguide

Takuro TAJIMA  Ho-Jin SONG  Makoto YAITA  

IEICE TRANSACTIONS on Electronics   Vol.E98-C   No.12   pp.1120-1127
Publication Date: 2015/12/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E98.C.1120
Type of Manuscript: Special Section PAPER (Special Section on Terahertz Waves Coming to the Real World)
terahertz,  transition,  packaging,  LTCC,  

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A 300-GHz hetero-generous package solution with a combination of a polyimide microstrip-to-waveguide transition on low-temperature co-fired ceramic (LTCC) is presented. To assemble three parts — a metal back-short, polyimide transition, and LTCC substrate integrated waveguide (SIW) — a ridged microstructure beside the microstrip probe was implemented to reduce the air gap on the broadwall of a back-short. A back-to-back transition exhibited an insertion loss of 4.4 dB at 300 GHz and 49-GHz bandwidth with less than a 10-dB return loss. By evaluating loss of the microstrip line and SIW, we estimated the loss for a single transition, which was 0.9 dB at 300 GHz. The probe transition with ridged metal successfully suppressed the unwanted dip in transmission characteristics and eased the difficulty in assembly. The compact transition is easy to integrate in an antenna-in-package with an MMIC chip by combining suitable substrate materials for the transition and package.