Abstract: An inverted-F-shaped antenna pattern is formed as a driven element on the obverse-side surface of a glass-epoxy circuit board. This antenna pattern has a feeding conductor pattern connected to a feeding transmission path formed on the obverse-side surface of the circuit board and a grounding conductor pattern connected to a grounding conductor portion formed on the obverse-side surface of the circuit board. Moreover, an inverted-L-shaped antenna pattern is formed as a passive element on the reverse-side surface of the circuit board. This antenna pattern has a grounding conductor pattern connected to a grounding conductor portion formed on the reverse-side surface of the circuit board. Forming the inverted-F-shaped antenna pattern and the inverted-L-shaped antenna pattern so as to overlap each other yields a laminate pattern antenna that is usable in a wide frequency range.

Abstract: At least one of the following requirements is satisfied. A position of a curvature center of an arcuate portion in at least one of waveguide plates is selected between a connecting member and a power feeder, in accordance with a desired horizontal beam radiation characteristic. A curvature radius of the arcuate portion in at least one of the waveguide plates is selected in accordance with a desired vertical beam radiation characteristic. A slanted angle of a peripheral face of the arcuate portion, which connects a top face and a bottom face of each waveguide plate, in at least one of the waveguide plates is selected in accordance with a desired vertical beam radiation characteristic.

Abstract: An optical multi-demultiplexer of the present invention comprises an input waveguide to which wavelength division multiple signals are applied, a plurality of output waveguides for demultiplexing and outputting the wavelength division multiple signals, an arrayed waveguide including a plurality of channel waveguides having different waveguide lengths, an input slab waveguide, and an output slab waveguide. The input slab waveguide is provided between the input waveguide and the arrayed waveguide. The output slab waveguide is provided between the arrayed waveguide and the output waveguides. The input slab waveguide is formed with tapered island regions having a refractive index lower than that of the core layer of the slab waveguide. The island regions are situated in positions opposite the channel waveguides of the arrayed waveguide.

Abstract: A thin plane antenna that copes with the horizontally polarized waves and the vertically polarized waves, or the levo-rotary polarized waves and the dextro-rotary polarized waves, and in which a loop-shaped plane antenna element (12) is arranged in parallel with a ground plane (15), and a first feeder conductor (13) and a second feeder conductor (14) having feeding points displayed by 90 degrees are arranged between the plane antenna element and the ground plane. Central conductors (18a) and (19a) of the coaxial lines are connected to the first and second feeder conductors, and external conductors (18b) and (19b) thereof are connected to the ground plane to feed electric power to the antenna element through the electromagnetic coupling. When the electric power is fed from the first feeder conductor (13), the horizontally polarized waves are radiated and when the electric power is fed from the second feeder conductor (14), the vertically polarized waves are radiated.

Abstract: An inverted-F-shaped antenna pattern is formed as a driven element on the obverse-side surface of a glass-epoxy circuit board. This antenna pattern has a feeding conductor pattern connected to a feeding transmission path formed on the obverse-side surface of the circuit board and a grounding conductor pattern connected to a grounding conductor portion formed on the obverse-side surface of the circuit board. Moreover, an inverted-L-shaped antenna pattern is formed as a passive element on the reverse-side surface of the circuit board. This antenna pattern has a grounding conductor pattern connected to a grounding conductor portion formed on the reverse-side surface of the circuit board. Forming the inverted-F-shaped antenna pattern and the inverted-L-shaped antenna pattern so as to overlap each other yields a laminate pattern antenna that is usable in a wide frequency range.

Abstract: Taking the spiral circumference, C, of a single wire spiral antenna as 2.3 .lambda. (.lambda. being the wavelength at the operating frequency), for example, the beam radiated from an axis Z perpendicular to the antenna surface is tilted. The beam tilt angle changes with the spiral circumference, C, and the spiral circumference, C, is set to between 2 .lambda. and 3 .lambda..

Abstract: A circular polarization microstrip line antenna transmits and receives right-handed and left-handed circularly polarized waves by one microstrip line antenna. A dielectric sheet 3 is laid on a metal base 4, and a flexible film 2 is laid on the dielectric sheet 3. Microstrip lines 5 are formed at the right and left sides of the surface of the flexible film 2. Rectangular waveguides 8 are arranged under the right and left ends of the metal base 4, a hole 9 is perforated at the upper surface of the rectangular waveguide 8, a hole 10 is perforated at the positoin opposed to the hole 9 of the metal base 4, and inverted L-shaped feeding pins 11 are inserted to the holes 9 and 10. The horizontal part 13 of the feeding pin 11 is interposed between the flexible film 2 and the dielectric sheet 3, and the horizontal part 13 is opposed to the right and left ends 5a of the microstrip line 5.

Abstract: A loop antenna for a circularly polarized wave can operate in a wide frequency range and can be simply constructed. A radiating power fed to a feeding point via a coaxial line and a feeder conductor is transmitted through an I-shape conductor to a C-type loop element disposed in spaced facing relation to a ground plane. By the action of a cutoff part formed on the C-type loop element, the C-type loop element radiates a circularly polarized wave. An angle of between 35.degree. and 45.degree. formed by the I-shape conductor and the cutoff part.

Abstract: A plurality of insulators are disposed in holes, respectively, defined in a metal plate of a waveguide of a circularly-polarized-wave flat antenna. Each insulator has a through-hole and a protrusion. The through-hole extends from the outside of the metal plate to the inside of the waveguide. The protrusion protrudes outward beyond the metal plate. The protrusion has a groove which is open to the outside. Curl antenna elements each have a shaft portion, an arm portion, and a curl portion. The shaft portion is fitted in the through-hole of the insulator and partly protrudes outward from the metal plate. The arm portion extends from the protruded end of the shaft portion. The curl portion is in a substantially helical shape and connected to the top of the arm portion.

Abstract: A parabolic antenna for SHF band having a primary feeder and a reflector is improved by using a backfire helical antenna as a primary feeder, which is fed by using a coaxial cable. The backfire helical antenna has a matching disc coupled with an outer conductor of the coaxial cable feeder, and a coil, one end of which is coupled with an inner conductor of said coaxial cable. The other end of the coil is free standing. The coil is positioned so that the axis of the coil coincides with the axis of the reflector, and the feed end of the coil locates nearer to the reflector than the free standing end of the coil. The present antenna is useful in particular for a receiving antenna for a direct satellite broadcasting.