SU365802A1 - COAXIAL RESONATOR WITH ELECTRIC FREQUENCY ADJUSTMENT - Google Patents

Description

one

The invention relates to the field of radio engineering and can be used in the design of oscillatory systems with electrical tuning.

Known coaxial resonators with electrical frequency tuning, consisting of a cylindrical outer conductor, a helical inner conductor, and a varicap switched on at the input of the resonator, have a narrow working frequency range.

The purpose of the invention is to expand the operating frequency range of the resonator. For this, between the outer and inner conductors of the resonator, for example, at its end, an additional varicap is connected, electrically conjugated with the said main varicap.

FIG. 1 and 2 show variants of the resonator; in fig. 3 and 4 are their schematic diagrams; in fig. 5 - their equivalent circuit.

The proposed resonator consists of an outer conductor /, an inner conductor 2 and two varicaps 3 n 4. The outer conductor is made in the form of a pipe of circular ill-shaped rectangular (square) cross section. The inner conductor is a coil held on the axis of the resonator by means of a rod 5 made of a dielectric with good high-frequency properties, for example, of ceramics.

The rod 5 is held on the axis of the resonator by the dielectric washer 6 or is fixed on the short jumper of the resonator.

Varicap 3 is included at the inlet of the coaxial line with a spiral inner conductor. Varicap 4 is connected at the open end of the resonator {fig. 1) or at a point different from the point at the end of the resonator (Fig. 2). The coupling of the varicaps is carried out by applying to them the same magnitude of the return stabilized voltage from a single DC source. Therefore, when the voltage changes on one varicap, when the frequency is tuned, the voltage on the other changes by the same amount.

The mixing voltage (reverse voltage) on the varicaps is supplied by a conductor through the end and side surfaces of the outer conductor of the resonator. To prevent possible radiation, the conductor from the bias source is connected to one end of the varicaps via blocking capacitors 7 and S. The quality factor and the capacitance of the capacitors must be much larger than the quality factor and the barrier capacitance of the varicaps. The choke 9 blocks the high-frequency mixing source, forming a low-pass filter with the blocking capacitors.

The length of the spiral resonator with electric frequency setting should be equal to or less than a quarter of the minimum wavelength (I / 4), as shown in FIG. 3 and 4. The barrier capacities of the Cdz and Cd4 conjugate varicaps are also shown here. This allows, by changing the varicap 4 barrier capacitance, to vary the equivalent inductance of the resonator. Since the varicaps are conjugate, when the equivalent inductance changes, the constant changes in the same direction and the capacitance C of the spiral resonator.

Thus, the presence of two conjugate varicaps, appropriately included in the resonator, allows simultaneously and consistently changing the equivalent parameters of the resonator, as shown in FIG. 5, i.e., inductive-capacitive tuning. This provides a wide range of tunable frequencies and improves the frequency of the tuning curve in frequency as a function of the bias voltage.

Subject invention

An electrically tuned coaxial resonator consisting of a cylindrical outer conductor, a helical inner conductor, and a varicap switched on at the resonator input, characterized in that, in order to expand the operating frequency range, between the outer and inner conductors of the resonator, for example, at its end an additional varicap electrically conjugated with said basic varicap.

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