Spontaneous carrier lifetimes in InGaAsP/InP double heterostructure lasers emitting at1.3µm were experimentally determined from lasing delay time measarement. Various step-current superposed on bias current was applied to a laser diode with 20 µm-stripe geometry. The carrier lifetime apparently decreased with increasing bias current from 4-5 ns at non-biased state to2 ns at well biased state. This change in the measured lifetime was explained by considering the effect of junction capacitance. It was shown that the effect was almost removed by the application of bias current of more than1 kAcm-2. µm-1 and then the intrinsic lifetime was obtained. Deduced carrier lifetime well agreed with that estimated from relaxation oscillation measurement.

A novel millimeter-wave planar leaky-wave antenna is described which consists of a dielectric slab loaded by metallic periodic strips. Several new techniques are discussed, such as an air-gapped dielectric waveguide to reduce conductor loss of the ground plane, a canceling array to suppress the reflections in the waveguide due to the metallic strips, a compact feed, and a simple polarizer. By applying these new techniques, we achieved an excellent antenna efficiency, exceeding 70% at 76 GHz band for both vertical and 45-degree inclined linear polarizations.

We propose a novel method for measuring the matched total radiated power (TRP) and matched total radiated sensitivity (TRS) of small radio terminals, called over-the-air (OTA) measurement, using a spheroidal coupler (SC). To measure these parameters accurately in a multiple-reflection environment, such as in an SC, we developed two key techniques, i.e. displacement method and reflection compensation method, and verified their effectiveness by several simulations and fundamental experiments on a test transmitter. We also describe an absolute method for measuring antenna radiation efficiency using the displacement method. Furthermore, we describe TRP and TRS measurements for actual UMTS (Universal Mobile Telecommunications System) terminals, and verify that the proposed method achieves quick measurements with good accuracy. The SC provides a compact, low-cost OTA measurement system with high sensitivity and high speed.