Abstract: A bandstop filter where variation in characteristics is suppressed to minimum and which realizes an increased production yield. The physical length of a line joint portion between a main line and an oscillator can be enlarged by providing an impedance non-continuous structure portion in a strip conductor of the oscillator. In comparison to the case where the impedance non-continuous structure portion is not provided, the width of a joint slit required to obtain an equal joint amount can be enlarged. When the joint slit width is enlarged, variation in filter characteristics caused by pattern accuracy can be reduced because of the enlarged joint slip width, thus improving a filter yield. This means that pattern accuracy requirement for production is loosened. Freedom in selecting a dielectric substrate is increased, which also provides an advantage that a filter can be produced using a less expensive dielectric substrate with not very high pattern accuracy.

Abstract: A bandstop filter where variation in characteristics is suppressed to minimum and which realizes an increased production yield. The physical length of a line joint portion between a main line and an oscillator can be enlarged by providing an impedance non-continuous structure portion in a strip conductor of the oscillator. In comparison to the case where the impedance non-continuous structure portion is not provided, the width of a joint slit required to obtain an equal joint amount can be enlarged. When the joint slit width is enlarged, variation in filter characteristics caused by pattern accuracy can be reduced because of the enlarged joint slip width, thus improving a filter yield. This means that pattern accuracy requirement for production is loosened. Freedom in selecting a dielectric substrate is increased, which also provides an advantage that a filter can be produced using a less expensive dielectric substrate with not very high pattern accuracy.

Abstract: The present invention includes: a first main waveguide 1; a T-branch circuit 3 connected thereto; a first low-pass filter 5 connected thereto; a band-pass filter 7 connected to the first T-branch circuit 3; a first converter 8 connected to the first low-pass filter 5 for converting transmission lines between a waveguide and a microwave integrated circuit; an amplifier 10 connected to the first converter and structured by the microwave integrated circuit; a second converter 9 connected thereto for converting transmission lines between a waveguide and the microwave integrated circuit; a second low-pass filter 6 connected thereto; a second T-branch circuit 4 connected to the second low-pass filter and the band-pass filter 7; and a second main waveguide 2 connected to the second T-branch circuit.

Abstract: The present invention includes: a first main waveguide 1; a T-branch circuit 3 connected thereto; a first low-pass filter 5 connected thereto; a band-pass filter 7 connected to the first T-branch circuit 3; a first converter 8 connected to the first low-pass filter 5 for converting transmission lines between a waveguide and a microwave integrated circuit; an amplifier 10 connected to the first converter and structured by the microwave integrated circuit; a second converter 9 connected thereto for converting transmission lines between a waveguide and the microwave integrated circuit; a second low-pass filter 6 connected thereto; a second T-branch circuit 4 connected to the second low-pass filter and the band-pass filter 7; and a second main waveguide 2 connected to the second T-branch circuit.

Abstract: It is an object of the present invention to realize a low-pass filter that has an increased number of stages of filter elements and can obtain a large combined capacitance with a simple configuration of a plane circuit, can set an attenuation pole in the vicinity of a pass band and has a steep out-of band attenuation characteristic. In order to attain such an object, three or more top end open stubs, which are set to have a large electric length in a range in which a length of is shorter than ¼ of a wavelength of a pass frequency, are disposed substantially in parallel so that their respective open ends face an identical direction to thereby form a combined line, and a high impedance line that is shorter than the wavelength of the pass frequency is connected to at least one part among parts between neighboring ends on the opposite side of open ends of the top end open stubs.

Abstract: It is an object of the present invention to realize a low-pass filter that has an increased number of stages of filter elements and can obtain a large combined capacitance with a simple configuration of a plane circuit, can set an attenuation pole in the vicinity of a pass band and has a steep out-of band attenuation characteristic. In order to attain such an object, three or more top end open stubs, which are set to have a large electric length in a range in which a length of is shorter than ¼ of a wavelength of a pass frequency, are disposed substantially in parallel so that their respective open ends face an identical direction to thereby form a combined line, and a high impedance line that is shorter than the wavelength of the pass frequency is connected to at least one part among parts between neighboring ends on the opposite side of open ends of the top end open stubs.

Abstract: One matching circuit (8-2) comprises a transmission line (6b) of a predetermined electrical length and a parallel resonance circuit (5) connected in parallel with the transmission line. The resonance circuit has a resonant frequency f2 and a predetermined susceptance at a frequency f1 lower than the frequency f2. ANother matching circuit (8-1) comprises a transmission line (6a) of a predetermined electrical length and a capacitor element (b 3a) connected in series with the transmission line between an input terminal (2) of an antenna (1) and the matching circuit (8-2) so that the input impedence of the antenna at the frequency f2 may match the characteristic impedance of an external circuit (10).

Abstract: An antenna device including matching circuits corresponding to reflection coefficients of antenna elements determined by taking into account the couplings between the antenna elements occurring when the antenna elements are excited with corresponding excitation amplitudes and excitation phases at each of operational frequencies.

Abstract: An antenna device including matching circuits corresponding to reflection coefficients of antenna elements determined by taking into account the couplings between the antenna elements occurring when the antenna elements are excited with corresponding excitation amplitudes and excitation phases at each of operational frequencies.

Abstract: A low-pass filter includes metal stub conductors mounted on a signal conductor at midpoints of adjacent high impedance sections of the signal conductor. The metal stub conductors prevent the occurrence of resonance between the high impedance sections, thereby providing a large attenuation value over a wide frequency band above the cutoff frequency of the low-pass filter.

Abstract: The present invention aims at supplying an electric current to a helical antenna in a non-contacting manner. A dielectric tube is provided on an outer surface thereof with a feeding input terminal, strip conductors and hybrid ICs. The dielectric tube is provided on an inner surface thereof with a base conductor and slots. A helical antenna is inserted into the portion of an inner space of the dielectric tube which is opposed to the slots. The strip conductors cross the slots via the wall of the dielectric tube. The slots are connected electromagnetically to the helical antenna radiation elements in a non-contacting manner. The slots are connected electromagnetically to the strip conductors. A microwave drives the helical antenna radiation elements via the input terminal, hybrid ICs strip conductors and slots.