A description for high-speed communication networks for the 21st century is roughly sketched, and the technical development trends in high-frequency and high-speed devices are briefly forecasted. Four examples of devices under development are reported: 76-GHz flip-chip MMIC's for car-radar systems, a cost-effective RF module for millimeter-wave wireless systems, a 10-Gbps demultiplexer for optical fiber communication systems, and a GaAs microwave signal processor for active phased-array systems. Considering as technological trends evolve further, this paper also introduces the software radio concept and the fusion of wireless and optical technologies for cost-effective wireless communication equipment and end-user services.

As a first step towards the realization of high-efficiency on-chip antennas for 60GHz-band wireless personal area networks, this paper proposes the fabrication of a patch antenna placed on a 200µm thick dielectric resin and fed through a hole in a silicon chip. Despite the large tan δ of the adopted material (0.015 at 50GHz), the thick resin reduces the conductor loss at the radiating element and a radiation efficiency of 78%, which includes the connecting loss from the bottom is predicted by simulation. This calculated value is verified in the millimeter-wave band by experiments in a reverberation chamber. Six stirrers are installed, one on each wall in the chamber, to create a statistical Rayleigh environment. The manufactured prototype antenna with a test jig demonstrates the radiation efficiency of 75% in the reverberation chamber. This agrees well with the simulated value of 76%, while the statistical measurement uncertainty of our handmade reverberation chamber is calculated as ±0.14dB.

Transitions between a post-wall waveguide and a microstrip line are proposed as the key components for cost-effective millimeter-wave modules. A transition with a coaxial structure is investigated for LTCC laminated layers and 11.3% bandwidth for the reflection smaller than -15 dB is realized in 60 GHz band. The overall connector loss with 1 cm post-wall would be about 0.8 dB. The degradation due to fabrication error is also assessed. The transition in LTCC substrate fulfills electrical and manufacturing demands in millimeter-wave bands.

Interfaces between a coaxial structure and a post-wall waveguide are proposed as the essential components for cost-effective millimeter-wave modules. PTFE substrate is selected in terms of loss and manufacturability. The reflection and the transmission characteristics are investigated. The short-stepped and the short-taper-stepped feeding structures provide 14.7% and 13.2% bandwidths for the reflection smaller than -15 dB, respectively. The 4640 mm2 size antenna fed by the short-stepped structure in PTFE substrate gives 27.3 dBi with 58.2% efficiency at 60.0 GHz. Feeding structures in PTFE substrate fulfill electrical and manufacturing demands in millimeter-wave bands.

The design and performance of a millimeter-wave video transmission system using 60-GHz band for indoor broadcasting-satellite (BS) signals transmission is presented. This system can transmit multiple video signals such as broadcasting signals and user-oriented signals to a television set indoors. To minimize the local oscillator's frequency offset and phase-noise effects, the system uses a remote-heterodyne scheme. Based on the concept, the system is developed to meet required carrier-to-noise-power-ratio (CNR) and 3rd-order intermodulation (IM). The BS transmission was experimentally done by using the transmitter and receiver setup. The results are very promising and show the feasibility of the system.

For the realization of a high-efficiency antenna for 60GHz-band wireless personal area network, we propose placing a CMOS RF circuit and an antenna on opposing sides of a silicon chip. They are connected with low loss by a coaxial-line structure using a hole opening in the chip. Since the CMOS circuit is driven differentially, a differential-feed antenna is used. In this paper, we design and measure a differential-feed square patch antenna on a silicon chip. To enhance the radiation efficiency, it is placed on a 200µm thick resin layer. The calculated radiation efficiency of 79% includes the connection loss. A prototype antenna is measured in a reverberation chamber, and its radiation efficiency is estimated to be about 81±3%.