RU2815333C1 - Microstrip power divider with extended bandwidth - Google Patents

Abstract

FIELD: microwave technology.

SUBSTANCE: microstrip power divider comprising two microstrip output transmission lines, each connected to an input microstrip transmission line, and a resistor connected between the output transmission lines at a quarter-wave distance from the branch point. In this case, the microstrip output quarter-wave sections of lines that make up the ring are connected to the input microstrip line through a microstrip matching transforming quarter-wave section, and one quarter-wave short-circuited loop with a characteristic impedance of 50 Ohms or more is connected to the junction point of the transforming section with the ring.

EFFECT: expansion of the operating frequency band.

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Description

The invention relates to microwave technology and is intended for the construction of devices for distributing signals between transmission lines in the centimeter wavelength range.

The simplest common-mode stripline power divider is known [Wilkinson E.J. An n-way hybrid power divider // IRE Trans. 1960. Vol. MTT-8, No. 1], containing one quarter-wave transforming section and one resistor, which ensures matching and decoupling of its outputs at the mid-range frequency. The operating band of this divider with a main center frequency of 10 GHz is 3.4 GHz with an isolation of -20 dB.

A stripline power divider RU 2392702 C2 is known, containing two output transmission lines, each of which is connected to an input transmission line, and at least one resistor connected between the output transmission lines at some distance from the branching point, characterized in that next to A resistor and parallel to it are additionally located a conductive strip, the ends of which are opposite the conductors of the output transmission lines and have a capacitive coupling with them. This design seems quite complex and the implementation of such a solution in microstrip design is difficult in serial and large-scale production, given the need for customization.

Ultra-wideband power dividers RU 2621887 C1, RU 2709107, RU 2334312 C1 and others with large operating frequency bands are known. However, they have large losses of transmitted power in the operating frequency band, which is unacceptable when using these designs, for example, in powerful microwave amplifiers.

The purpose of the invention is to expand the operating frequency band at an acceptable level of isolation between the outputs of the divider and matching of the input and outputs at frequencies in the centimeter range. Improving the matching and decoupling of the divider outputs improves the performance of microwave devices that include a power divider. This reduces reflection power loss and reduces unwanted coupling between two transmission lines.

This goal is achieved by introducing the following changes: in the known simplest common-mode ring power divider [Wilkinson E.J. An n-way hybrid power divider // IRE Trans. 1960. Vol. MTT-8, No. 1], containing two microstrip output transmission lines, each of which is connected to the input microstrip transmission line, and a resistor connected between the output transmission lines at a quarter-wave distance from the branching point, according to the invention between the ring and the input line is used as a matching quarter-wave transformer and one or two quarter-wave short-circuited loops with a characteristic impedance of one loop of 50 Ohms or more or two loops of 100 Ohms or more for each are connected to the junction point of the transforming section with the ring.

In FIG. Figure 1 shows the configuration of strip conductors of a strip power divider with an extended band, where the values of their wave impedances are indicated with the lengths of these conductors and the resistor connected between them with an indication of its ohmic resistance. Capacitor C is used as an element that short-circuits the 75-ohm loop at an average operating frequency. Direct galvanic grounding of the loop is possible without the need for galvanic isolation of the divider from the ground.

In FIG. Figure 2 shows a stripline power divider with an extended band, indicating the positions of its constituent elements. The input 50-ohm section 1 is connected to a quarter-wave transforming section 2. This section 2, in turn, is connected to a divider ring formed by two quarter-wave sections 3, and to a loop 6 with a characteristic impedance of 75 Ohms, the other end of which is connected to a loop 7 with a characteristic impedance 17 Ohm, made in the form of a semicircle with a radius of a quarter wave at an average operating frequency. Sections 3 are connected at their output ends to each other by a resistor 4. 50-ohm channels 5 are connected to the output ends of sections 3.

In FIG. 3 shows the same strip divider, but with the replacement of one loop as in FIG. 1 two loops with double impedance (150 Ohm).

In FIG. 4 shows the same strip divider, but with the replacement of one loop as in FIG. 2 two loops with double impedance (150 Ohm).

In FIG. 5 shows the same strip divider, but with a loop arrangement similar to Fig. 1 along the axis of symmetry of the structure in the direction towards the output of the divider with an insulated conductive jumper 8 above the resistor.

Let's consider the operation of the proposed solution for expanding the bandwidth of a microstrip divider.

In this design, a short-circuited loop or two loops a quarter wave long at the middle frequency range and having a characteristic impedance of one loop of 50 Ohms or more or two loops of 100 Ohms or more for each, is connected to the joining point of the quarter-wave transforming section located at the input of the divider, and a divider ring consisting of two quarter-wave segments and a resistor connecting them at the output of the divider. Such a connection of a short-circuited loop (or two loops) expands the operating band of the divider due to the fact that the quarter-wave loop introduces into the circuit at the connection point reactive conductivities of the opposite sign in relation to the reactive conductances at this point in the circuit without this loop, so that compensation occurs in a wide band frequency As a result, the design bandwidth and isolation of the divider outputs are expanded by raising the edges of its transmission characteristics and improving isolation. A decoupling characteristic of the divider outputs with three minimums is formed, which makes it possible to expand the operating band compared to a simple Wilkinson divider.

All elements of the proposed extended-bandwidth microstrip power divider design are performed seamlessly using standard photolithography technology and do not require any further tuning. When using 150-ohm cables, they can be made in the form of thin wires lying on the surface of a dielectric plate. Thus, a metal wire with a diameter of 0.012 mm located on a polycore plate one millimeter thick, metallized on the reverse side, forms a line with the required characteristic impedance of 150 Ohms.

The examples of the divider shown in Figures 1-5 have the following characteristics in the 7-13 GHz frequency band: isolation between output channels -18 dB, signal attenuation (division) per pass -3.05 dB, input return loss -20 dB, output return loss -18 dB.

The simplest common-mode stripline power divider according to the Wilkinson circuit has a bandwidth of 7.6-12.2 GHz with the same isolation between the output channels.

Claims (1)

A microstrip power divider containing two microstrip output transmission lines, each of which is connected to an input microstrip transmission line, and a resistor connected between the output transmission lines at a quarter-wave distance from the branching point, characterized in that the ring microstrip output quarter-wave sections of lines are connected to the input microstrip line through the microstrip matching transforming quarter-wave section, and one quarter-wave short-circuited loop with a characteristic impedance of 50 Ohms or more is connected to the junction point of the transforming section with the ring, or two quarter-wave short-circuited cables with a characteristic impedance of 100 Ohms or more are connected.