Acknowledgement I would especially like to express my most sincere thanks to my advisor, Professor Masayoshi Aikawa, for his invaluable guidance, advice, encouragement and support throughout the completion of my study and this thesis. I would also like to express my appreciation to the members of my thesis committee, Professor Kohei Arai, Professor Tatsuya Furukawa, Associate Professor Sumio Fu...

This paper presents a coplanar waveguide fed rectangular slot antenna tuned by a patch stub. The presented antenna has 98% impedance bandwidth, and 6 dB average gain. The antenna can be used in phased array applications with more than 61% usable bandwidth.

A new four elements compact antenna array is presented and discussed to achieve enhanced phase resolution without sacrificing the array output power. This structure inspired by the Ormia Ochracea’s coupled ears. The analogy between this insect acute directional hearing capabilities and the electrically compact antenna array is used to enhance the array sensitivity to direction of arrival estima...

Many kinds of microstrip array antennas have been developed in the millimeter-wave band. In order to avoid feeding loss and the decrease of antenna gain by beam shift due to frequency changes, center-fed array antennas are advantageous. In this case, the element spacing around the feeding circuit of the transition from the waveguide to two microstrip lines is larger than one wavelength. Therefo...

A wideband dual-polarized slot array antenna based on hollow waveguide (HW) is presented in this article. Its wide bandwidth and high performance are enabled by two separate feeding networks, from the side bottom, using square coaxial line ridge structures, respectively. The full-corporate-feed networks excite radiation slots a one-to-one fashion without backed cavities. Tight element spacing m...

A new design of coplanar waveguide (CPW)-fed antenna with circular polarization (CP) and excellent impedance matching is presented. In this design a pair of circular-shaped slits is applied to opposite corners of the slot for enhancing the impedance matching and realizes bandwidth of 134.43% across 2.98-15.20 GHz for VSWR≤2. Furthermore this structure exhibits axial ration bandwidth (ARBW) of 3...

A proper antenna to couple to a microstrip Microwave Kinetic Inductance Detector (MKID) is designed and simulated. A twin-slot microstrip-fed inline antenna is designed for frequency band of 600-720~GHz integrated with an elliptical lens and coupled to the MKID. A systematic design procedure for design of such antenna with microstrip inline feeding is presented. Whole structure of lens and twin...