RU2789181C1 - Broadband dc supply circuit for strip line - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: invention relates to the field of radio engineering, in particular to circuits for supplying direct current to strip lines. To create a broadband DC supply circuit to a strip line containing a quarter-wave stub connected in series, one end of which is connected to the strip line, the other end is connected to a capacitor, in turn, with a grounded opposite lining, and a capacitor, a section was introduced with a symmetrical bifurcation of this line and connection quarter-wave trail to the middle of one of the branches of the bifurcated line.

EFFECT: increasing the broadband isolation over the microwave DC source and strip line.

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Description

The proposed technical solution relates to the field of radio engineering, in particular to circuits for supplying direct current to strip lines.

A known circuit for supplying a control bias through a blocking capacitance connected in series with a switching diode. This control system is mainly applicable for microstrip switches and provides isolation from the microwave path of the DC power supply circuits for diodes. (Control of the switch mode through the blocking capacitance, Fig. 9.14, "Design and calculation of strip devices" edited by I.S. Kovalev, M: Soviet radio 1974, p. 233).

Known control circuit through the "T" branch of the waveguide, taken as a prototype. In a known circuit, a waveguide branch is a parallel loop, one end of which is connected to the microwave path, and the other end is closed to the housing at high frequency through a capacitor. The control voltage is applied to the connection point of the loop and the capacitor. The length of the loop is chosen equal to a quarter of the length of the operating wave. The main purpose of a capacitor connected through a loop parallel to the diode is to create a decoupling of power circuits with a microwave path. (Control system through the T branch of the waveguide, Fig. 9.12, "Design and calculation of strip devices" edited by I.S. Kovalev, M: Soviet radio 1974, p. 232).

The disadvantage of the prototype is the low broadband decoupling over the microwave DC source and the strip line, which is important when creating, for example, amplifiers based on semiconductor devices that have a gain boost at low frequencies, which leads to self-excitation of amplifiers with insufficient decoupling in a wide frequency band.

The technical problem to be solved is to increase the broadband isolation of the microwave DC source and the strip line.

To solve the stated technical problem, it is proposed to use a broadband DC supply circuit to a strip line, consisting of a quarter-wave loop and a capacitor connected in series, with one end of the loop connected to the strip line, and the other end to the capacitor, in turn grounded by the opposite lining, by introducing into the strip line a section line with a symmetrical bifurcation of this line and a quarter-wave loop connected to the middle of one of the branches of the bifurcated line.

The proposed technical solution satisfies the criterion of novelty, since there is no proposed solution to the technical problem in the published sources of information.

On FIG. 1 shows the circuit for supplying direct current to strip line 1, which contains section 2 of a symmetrically bifurcated strip line with a length of half a wave, a quarter-wave loop 3, connected at one end to the middle of one of the branches of the bifurcated line, and at the other end connected to capacitor 4, the opposite lining of which grounded. We will conditionally designate such a branch with the sign "Y".

The proposed circuit for supplying direct current to a strip line operates as follows. When the DC supply circuit is turned on in the strip line, through which microwave power is distributed, through the Y branch at the main frequency of its operating range, at the junction point of one of the branches of the bifurcated line and the quarter-wave loop, an idle mode occurs, since the other end of the loop is closed by a microwave capacitor to the ground and the loop is disconnected by microwave from the line. The microwave power in this case passes through a section of a symmetrically bifurcated strip line, the length of each branch of which is approximately equal to half the wavelength.

At a frequency two times lower, the main section, consisting of a series-connected quarter-wave loop and a half of a bifurcated line branch connected to it, together form a new quarter-wave loop, which also turns off the microwave strip line at the bifurcation point from the power input. In this case, the microwave power passes through another section of the bifurcated line.

At a frequency twice the fundamental frequency, a section consisting of a series-connected quarter-wave stub and a half of a bifurcated line branch connected to it, together form a new stub, the length of which is three-quarters of a wavelength at this frequency, and it also turns off the microwave strip line at the point splitting from the power input. In this case, the microwave power passes through another section of the bifurcated line.

Thus, three frequency-spaced decoupling centers appear along the microwave stripline from the DC supply circuit, having their own acceptable frequency ranges for a given decoupling level. With the superposition of their characteristics, an increase in the operating frequency range of the device as a whole is achieved.

As an example of the design of a broadband DC supply circuit to a strip line in FIG. 1 shows the topology of such a circuit with dimensions for an average frequency of 10 GHz. Dimensions are given in millimeters. A 1 mm thick polycor backing was used. The frequency range of this circuit in terms of loss in the strip line is not more than 0.1 dB is 12.2 GHz (from 3.95 GHz to 16.16 GHz), which is more than 2 times the range in designs using simple "T" taps for supplying direct current to the strip line.

If necessary, it is possible to obtain similar designs for medium frequencies up to 5 GHz by inversely proportional change in the size of the lengths of the sections with a change in frequency. So, for example, for an average frequency of 7 GHz, the frequency range will be 9 GHz (from 2.65 GHz to 11.6 GHz), and for 5 GHz, respectively, 4.85 GHz (from 2 GHz to 6.85 GHz). For fundamental (medium) frequencies below 5 GHz and above 10 GHz, a separate additional study of the design dimensions is required.

Claims (1)

A circuit for supplying direct current to a strip line, containing a quarter-wave stub and a capacitor connected in series, with one end of the quarter-wave stub connected to the strip line, and the other end to the capacitor, the opposite lining of which is grounded, characterized in that a section with a symmetrical bifurcation of this line and connecting a quarter-wave loop to the middle of one of the branches of the bifurcated line.

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