摘要:
A low noise oscillator is disclosed wherein the collector and base of a transistor are respectively biased at different voltages from a common voltage source to be conditioned for generating a high frequency oscillation with a resonant circuit connected to the emitter and collector. The high frequency oscillation developed at the base of the transistor is coupled to ground. A capacitive circuit is coupled between the collector and base of the transistor to eliminate the effect of a voltage-dependent capacitance inherently present in the transistor between its collector and base on the frequency of the oscillation in order to reduce the level of noise introduced to sidebands.
摘要:
A coaxial dielectric resonator for VHF-UHF band comprises a generally cylindrical dielectric body having a thick portion, a thin portion and a stepped portion interposed between the thick and thin portion. The outer and inner surfaces of the dielectric body are respectively covered by outer and inner conductors. Thus the resonator can be regarded as a series circuit of two lines having different impedance from each other. The axial length of the thick and thin portions may be changed so as to change electrical characteristics. With the provision of thick and thin dielectric portions, the spurious resonance frequencies may be set to values other than integral multiples of the fundamental resonance frequency. The stepped portion may be rounded or replaced with a tapered portion so that impedance gradually changes at the stepped or tapered portion from the thick portion to the thin portion or vice versa.
摘要:
In a coaxial filter arrangement having a plurality of coaxial resonators each having a bottomed metallic cylinder interposed between a dielectric plate and one end of a center conductor of each resonator, the peripheral wall portion of the metallic cylinder is received in the bore of an outer conductor having an open end and a closed end connected to the other end of the center conductor. In one embodiment, the bottom of the metallic cylinder has a convex portion at its center so that the bottom center projects outwardly. In another embodiment, an annular metallic member is interposed between the dielectric plate and the outer surface of the flat bottom of the metallic cylinder. Since the distance between bottoms of metallic cylinders of adjacent resonators is made large with this arrangement, influence due to leakage flux of electromagnetic field is small, while stray capacitance is negligibly small, thereby providing a filter having high performance and low loss.
摘要:
A wide band analog frequency divider circuit operable at a high frequency in the GHz band. The analog frequency divider circuit comprises an LC series circuit having a capacitor and an inductor connected between the anode and the cathode of a diode, and means for applying a forward bias to the diode. The input signal is supplied from the anode side of the diode, and the output is delivered from the cathode side, or the anode side if the cathode is grounded.
摘要:
A strip-line resonator comprises a first dielectric substrate having a conductive film on one surface thereof for connection to ground and a strip line on the other surface thereof and a second dielectric substrate having one surface thereof making contact with the strip line and a conductive film on the other surface thereof for connection to ground. Fused glass having a low melting point for is applied between the first and second substrates to bond them together. A portion of open-circuit end of the strip line is exposed and formed with slits or gap to facilitate frequency adjustment.
摘要:
A band-stop filter for VHF-UHF band comprises at least three series resonance circuits and at least two transmission lines each connected between the series resonance circuits. One of the transmission lines, which is connected to the input terminal of the band-stop filter, has an electrical length which is shorter or longer than the quarter wavelength of the center frequency of the stop band by more than 20 but less than 50 percent. When a band-stop filter comprises four transmission lines, one of the transmission lines, which is connected to the output terminal of the band-stop filter, has the same length as the transmission line connected to the input terminal. With this arrangement, the band-stop filter exhibits a sharp attenuation characteristic in a frequency range below or above the center frequency. Other transmission lines, which are not directly connected to either the input terminal or the output terminal, may have a length which is shorter or longer than the quarter wavelength by 5 to 20 percent so as to provide a sharper attenuation characteristic.
摘要:
In a bandpass filter having five or more resonator stages, a sub transmission line is coupled to the main transmission line at the first and fourth resonators. The first to fourth resonators provide peak attenuation points at both sides of the center frequency in the attenuation curve, while the remaining resonators following the fourth resonator further sharpen the attenuation characteristics of the bandpass filter. The main and sub transmission lines may be formed by striplines on a printed circuit board, while the sub transmission line can be capacity coupled to the main transmission line. Coupling capacitances are freely set by setting the length of each gap between adjacent striplines to a desired value. Thus, the peak attenuation points can be accurately controlled to provide a bandpass filter having superior characteristics.
摘要:
A microwave mixing circuit comprises a main transmission line having an input port for receiving an input high frequency and an output port, a band pass filter responsive to a local oscillation frequency, first and second band stop filters, and a mixing diode connected to the output port. The local oscillation frequency applied via the band pass filter to the main transmission line is prevented from being transmitted toward the input port because of the first band stop filter, while an image frequency produced by the diode is reflected by the second band stop filter to be applied to the diode.
摘要:
The width of a strip-line conductor in a TEM mode resonator is made wider at the center portion thereof, at which current is maximum, then the open-ended widths at both end portions of the conductor so that impedance of the center portion is lower than the impedances of both end portions. The impedance may be stepwisely or continuously varied, and spurious resonance frequencies may be determined by the impedance ratio between the higher and lower impedances. Such a resonator may be included in a band pass filter in such a manner that the band pass filter comprises at least one resonator whose spurious resonance frequencies differ from those of remaining resonators.
摘要:
A coaxial cavity resonator comprising an outer conductor and an inner conductor coaxially disposed in the outer conductor with one end of the inner conductor being connected to an end wall of the outer conductor to establish a short-circuit relationship and the other end of the inner conductor being spaced from the other end wall of the outer conductor to establish an open-circuit relationship. An intermediate hollow conductor is disposed coaxially with the inner and outer conductors and encircles a portion of the axial dimension of the inner conductor. The intermediate conductor has a closed end which is connected with the open-circuit end of the inner conductor.