In this paper, several parasitic elements are added to the circular microstrip antenna in order to increase its bandwidth. Three kinds of parasitic elements such as cone, circular plate, and ring types are applied and input VSWRs, radiation patterns, and input impedances are measured. The optimal sizes of each parasitic element are obtianed and the variations of the bandwidth according to the height from the patch are also measured. In thid case of the ring type, the optimum bandwidth is obtained at the height of 10mm from the patch to the parasitic element. In the cases of conical and circular plate types, the maximum bandwidth is obtained at the hight of 45mm form the patch to the parasitic elements.

An electric field due to point dipole within conductor-backed thin dielectric layer above the earth is calculated by using saddle point method When the dielectric layer is thin enough to support a cutoff mdoe, we show that the field may be approximated by sum of contributions of branch points of TE mode and poles of tM mode and that the branch points and poles contributions are interpreted as an evanescent lateral waves and leaky waves, respectively.

Effects of Co thickness on the formation of epitaxial $CoSi_2$ from the Co/Ti bilayer have been investigated. Ti and Co were sequentially deposited with the Ti thickness fixed at 5 or 10nm, while the Co thickness was varied from 5 to 30nm. The metal-deposited samples were then rapidly thermal-annealed in $N_2$ at $900^{\circ}C$ for 20 sec. Material properties of $CoSi_2$ thin films were analyzed by the 4-point probe, XRD, AES, andXTEM. When the as-deposited Co thickness was below 15nm, the $CoSi_2$ with high resistivity and rough interface was formed. On the other hand, when the Co thickness was above 15 nm, the epitaxial $CoSi_2$ with the resistivity of about 16 ~ 19 $\mu\Omega.cm$, uniform composition and thickness and flat interface was formed. Initial Ti thickness has sizable effect on the formation of $CoSi_2$, when the Co layer was very thin (~ 5 nm). But there was no significant effect of the Ti thickness for the initial Co thickness of above 15 nm.

An improved clock-feedthrough compensation scheme for switche dcurrent system is proposed. Both the signal dependent and the constant clock-feedthrough terms are cancelled by using both NMOS and PMOS current samplers and by adopting a source replication technique. The proposed current memory cell was fabricated with 0.6$\mu$m CMOS process. Both experimental and theoretical results on clock-feedthrough error reveal substantial reduction over the existing compensation schemes.

A new method to form the gate oxide and recrystllize the polycrystalline silicon (poly-Si) active layer simultaneously is proposed and fabricated successfully. During te irradiation of excimer laser, the poly-Si film is recrystallized, while the oxygen ion impurities injected into the amorphous silicon(a-Si) film are activated by laser energy and react with silicon atoms to form SiO2. We investigated the characteristics of the sample fabricated by proposed method using AES, TEM, AFM. The electrical performance of oxide was verified by ramp up voltage method. Our experimental results show that a high quality oxide, a pol-Si film with fine grain, and a smooth and clean interface between oxide and poly-Si film have been successfully obtained by the proposed fabrication method. The interface roughness of oxide/poly-Si fabricated by new method is superior to film by conventional fabrication os that the proposed method may improve the performance of poly-Si TFTs.

Design rules of directional coupler optical switches are discussed in consideration of parasitic couplings in the bending section. The parasitic coupling phenomenon is analyzed based on the coupled-mode theory and the solutions are represented in the form of the transfer matrix. The modified switching conditions due to the parasitic coupling are derived and the resultant switching diagrams are illustrated. It is revealed that the parallel section's length needs to be adjustd less than the coupling length $l_c(=\pi/2\textsc{k}o)$ to obtain the desired crosstalk and that the adjustment depends on the strength of the parasitic coupling. However, it is discovered that, for weak parasitic coupling, the switching voltage does not need to be altered but may maintain the same value as if no parasitic coupling is taken into account.

We proved the feasibiltiy of a parallel optical interconnection technique using single GRIN (graded-index) rod lens as an intermediate coupling device, which increases the working distance and makes packaging easy. The proposed technique shows relatively less dependency on misalignments. In this paper, for convensience of experiments, we applied this method to 4-channel coupling between two fiber arrays, and compared it with butt-coupling and the method of using ball lens. The comparison shows the feasibility of adopting the proposed method to the parallel interconnection between a laser diode array and an optical fiber array.