RU2667690C1 - Power splitter - Google Patents

Abstract

FIELD: radio equipment and communications.SUBSTANCE: invention relates to the radio equipment, particularly to the power splitters. Power splitter comprises input arm via the splitter from the transmission line quarter wave segments connected to the output arms, between which the ballast resistors are included, which connection forms the convex polygon figure. At that, each of the ballast resistors is made in the form of homogeneous transmission line segment with the rectangular shaped losses, divided in half by the metallized conductive strip with a width, equal to the introduced and connected thereto short-circuited loop width, with length of less than the operating range central frequency wavelength quarter.EFFECT: power splitter input and output matching improvement when using the ballast resistors with area equal to or greater than 32 mm.1 cl, 7 dwg

Description

The invention relates to microwave technology and can be widely used in systems of active phased array antennas, radio transmitting devices and systems using microwave power.

A known power divider containing a splitter of quarter-wave segments of transmission lines to the outputs of which are connected ballast decoupling resistors connected by a star (Wilkinson EJ An N-hybrid power divider // IRE Trans, on microwave theory and techniques. 1960, v. MTT-8, N 1.p. 116-118). Being linear and reciprocal, the Wilkinson divider can equally be used as a power adder.

Such film power dividers are widely used in practice with respect to low-signal devices, i.e. where the areas of ballast decoupling resistors are small and, as a result, their parasitic capacitances are small. When operating at a high power level, the areas of ballast resistors and, consequently, their parasitic capacities increase, which leads to a sharp deterioration in the matching of inputs and outputs, a decrease in isolation between the output arms, a decrease in direct transmission, an increase in losses in the ballast resistors, and a shift in the minimum frequency coefficient of a standing voltage wave (VSWR) and isolation maximum, etc. (see K.Ya. Aubakirov, V.I. Govorukhin, L.G. Plavsky, M.G. Rubanovich. Two-channel common-mode adder-power divider with compensation for spurious pa ballast resistor measurements. Radio engineering, N 6, 2011, pp. 59-63).

A known power divider (see ed. Certificate of the USSR N 1798840, Н01Р 5/12, БИ N 8, 02/28/93) containing an input arm connected via quarter-wave lengths of the transmission line to the output arms, while ballast resistors are connected between the output arms made in the form of segments of a transmission line with losses and connected to a star, to a common point of which a short-circuited loop is connected with a length less than a quarter of the wavelength of the center frequency of the operating range, and its input impedance is selected from the relations:

where Z _C , L is the impedance and the length of the length of the transmission line with losses;

γ is the propagation constant in the transmission line with losses;

- волновое сопротивление и длина шлейфа.Z _W

- wave impedance and loop length.

The introduction of a short-circuited loop power less than a quarter of the wavelength of the central frequency of the operating range with inductive input impedance into the power divider and the implementation of ballast resistors in the form of segments of the transmission line with losses can compensate for their stray capacitance and significantly improve the technical characteristics of the device (see the above article K. Ya. Aubakirov, VI Govorukhin and others. Two-channel common-mode adder-power divider with compensation of parasitic parameters of the ballast resistor. Engineering, N 6, 2011, pp. 59-63). However, their values, which concern, first of all, the characteristics of matching on the inputs and outputs, are not high enough. Their increase is possible due to the improvement of the electrical circuit of the device and the introduction of additional correction elements.

A power divider with optimal characteristics as agreed is also known, which is the prototype of the invention, which uses another option for connecting ballast resistors between adjacent output arms of the power divider, and their connection forms a convex polygon (see Mazepova O.I., Meshchanov V. P., Prokhorova N.I. et al. Handbook of Elements of Strip Technology / Ed. By A. L. Feldstein. - M .: Communication, 1979. 336 p.).

However, the claimed high technical characteristics by agreement can be obtained only when using point (non-reactive) ballast resistors. The use of 4 × 8 mm ² ballast resistors with an area of 32 mm ² significantly affects the characteristics of the device, so that its use in practical equipment is irrational.

The objective (technical result) of the present invention is to improve the coordination of the input and output of the power divider with ballast resistors with an area equal to or greater than 32 mm ² .

The problem is achieved in that in the power divider containing the input arm connected via a splitter of quarter-wave segments of the transmission line to the output arms, between which are included ballast resistors, the connection of which forms a convex polygon figure, each of the ballast resistors is made in the form of a segment of a uniform transmission line with losses of a rectangular shape, divided in half by a metallized conductive strip with a width equal to the width of a shorted circuit inserted and connected to it a short loop less than a quarter wavelength of the center frequency of the operating range.

In addition, additional short-circuited loops connected to each output arm with a length determined from the ratio can be introduced into the proposed power divider

where γ ₀ is the wavelength in the power divider at the center frequency of the operating range;

,

и короткозамкнутого шлейфа с входным сопротивлением Z_ВХШ1 = jρ_Ш1tgθ_Ш1,

;Z _VHE = Z _R (Z _ВХШ1 + Z _R thθ _R ) / (Z _R + Z _ВХШ1 thθ _R ) is the input resistance of the output arm branch of the power divider composed of a ballast resistor with parameters Z _R ,

,

and a short-circuit loop with input impedance Z _VHSh1 = jρ _Ш1 tgθ _Ш1 ,

;

ρ _Ш1 , ρ _Ш2 - wave impedances of short-circuited loops.

The initial formulas, equivalent circuits of the arm of the power divider, design relationships and notation are given in the works of K. Ya. Aubakirov, V.I. Govorukhin, Plavsky L.G., M.G. Rubanovich. Two-channel common-mode adder-power divider with compensation of parasitic parameters of the ballast resistor. Radio Engineering, N 6, 2011, p. 59-63 and V.I. Govorukhin, M.G. Rubanovich, N.E. Unruh. Wilkinson multi-channel common-mode combiners-dividers with compensation of spurious parameters of ballast resistors. Questions of Radio Electronics, General Technical Series, vol. 3, 2014, p. 102-114.

In FIG. 1 is a schematic electrical diagram of the proposed n-channel power divider, FIG. 2 is a variant of the circuit diagram of the electrical circuit of the proposed n-channel power divider with additional short-circuited loops introduced connected to each output arm of the power divider, FIG. 3 is an image of a ballast resistor in the form of a segment of a homogeneous transmission line with a rectangular loss, divided in half by a metallized conductive strip with a short-circuit loop attached to it, in FIG. 4 - frequency dependences of the technical characteristics of a three-channel power divider - prototype with point (non-reactive) ballast resistors, in FIG. 5 - frequency dependences of the technical characteristics of a three-channel power divider - prototype with ballast resistors of 4 × 8 mm ² each, in FIG. 6 - frequency dependences of the technical characteristics of the proposed three-channel power divider with ballast resistors in the form of a segment of a homogeneous transmission line with rectangular losses of 4 × 8 mm ² each, divided in half by a metallized conductive strip with a short-circuit loop attached to it, in FIG. 7 - the same, but with the introduction of additional short-circuited loops connected to each output arm of the power divider.

The power divider (Fig. 1) contains an input arm 1 connected through a splitter 2 of quarter-wave segments of the transmission line 3 to the output arms 4, between which are included ballast resistors 5, each of which is made in the form of a segment of a uniform transmission line with a rectangular loss, divided in half a metallized conductive strip 6 with a short-circuited loop 7 inserted and connected to it, less than a quarter of the wavelength of the center frequency of the operating range, the connection of ballast resistors forms the shape of a convex polygon. The output arms 4 of the power divider are loaded on the load resistance 8.

In the proposed power divider can be introduced additional short-circuited loops 9 connected to each output arm (Fig. 2), with a length determined from the ratio:

(обозначения приведены выше).

(designations are given above).

The power divider (Fig. 1) works as follows. When the input microwave signal arrives at the input arm 1, its power is evenly distributed by a splitter 2 from the quarter-wave segments of the transmission line 3 to all output arms 4 so that for identical and matched load resistances 8, these powers on all output arms 4 are equal in phase and in phase. For the case of a minimum area of ballast resistors 5, the power divider is a symmetrical multipole and at the center frequency it is consistent, and its outputs are almost completely decoupled. In powerful devices, it is necessary to use ballast resistors with a large area to dissipate significant power in the event of a mismatch or failure of one of the loads. The technical characteristics of such power dividers are significantly degraded, and therefore, to ensure their operability, it is necessary to reduce the effect of the effect associated with the use of ballast resistors with a large area.

In the proposed power divider, ballast resistors are connected between adjacent output arms of the device, and their connection forms a convex polygon figure. Spurious capacitance is compensated for each resistor by introducing a separate short-circuited loop with inductive input resistance connected to a metallized conductive strip of the resistor.

с индуктивным входным сопротивлением компенсирует распределенную паразитную емкость балластного резистора лишь частично, и поэтому подключение дополнительного второго короткозамкнутого шлейфа с параметрами Z_Ш2,

с таким же индуктивным входным сопротивлением позволяет устранить вредное влияние паразитной емкости балластного резистора почти полностью.A further increase in technical characteristics can be achieved by connecting an additional short-circuited loop to each output arm of the power divider. Indeed, the implementation of ballast resistors in the form of segments of homogeneous transmission lines with rectangular losses determines the uniform distribution of the stray capacitance of the ballast resistor along its length. The first short-circuited loop with parameters Z _Ш1 ,

with inductive input impedance compensates for the distributed stray capacitance of the ballast resistor only partially, and therefore the connection of an additional second short-circuited loop with parameters Z _Ш2 ,

with the same inductive input resistance, it eliminates the harmful effect of the parasitic capacitance of the ballast resistor almost completely.

, где R₀=50 Ом - стандартное входное и выходное сопротивления делителя мощности, n=3 - число его выходных плеч. Короткозамкнутые корректирующие шлейфы 7 и 9 с шириной полоска w=0.2 мм (ρ_Ш=90 Ом) и длинами

,

, как и балластные резисторы 5 выполнены на подложке из поликора с h=1 мм и толщиной полоска 0.008 мм.The calculated frequency dependences of the technical characteristics of the proposed and power divider - prototype in a three-channel version in the frequency range 600 ... 1400 MHz with a central frequency of 1000 MHz are presented in FIG. 4 ... 7. The quarter-wave lengths of transmission line 3 of splitter 2 are idealized lines with an air dielectric of 75 mm length and wave impedance

where R ₀ = 50 Ohm is the standard input and output resistance of the power divider, n = 3 is the number of its output arms. Short-circuited correction loops 7 and 9 with a strip width w = 0.2 mm (ρ _Ш = 90 Ohm) and lengths

,

, like ballast resistors 5 are made on a polycor substrate with h = 1 mm and a strip thickness of 0.008 mm.

The potential capabilities of the power divider prototype with point (non-reactive) ballast resistors are shown in FIG. 4. The coefficient of direct transmission | S ₂₁ | the same in the considered frequency band 0.6 ... 1.4 GHz and is close to the theoretical value of -4.77 dB. The parameter | S ₂₃ |, characterizing the isolation between the output arms of the device, exceeds 70 dB at the center frequency of the operating range, the bandwidth at the level of -25 dB is 248.6 MHz. The quality of matching at the input and outputs of the device is determined by the width of its matching band according to the level of permissible value of VSWR. For a power divider - a prototype with idealized point-type ballast resistors, the input matching band at the KCBH ₁ = 1.5 level is 460 MHz, in outputs, it significantly exceeds the considered frequency range 0.6 ... 1.4 GHz even at the VSWR level ₂ , ₃ ≤1.15.

The specified technical characteristics can be obtained at relatively low operating frequencies, for example, in the meter wavelength range, where the geometric dimensions of circuit elements, in particular ballast resistors, are small compared to a quarter wavelength of the upper frequency of the operating range. In the considered decimeter wavelength range shown in FIG. 4, frequency dependences cannot be obtained fundamentally due to the need to use ballast resistors with sufficiently large geometric dimensions, determined by the level of power dissipated on them.

Changing the technical characteristics of a power divider - prototype when using ballast resistors with a base size of 4 × 8 mm ² with an area of 32 mm ² (see the above work by K.Ya. Aubakirov, V.I. Govorukhin, L.G. Plavsky, M.G. Rubanovich A two-channel common-mode adder-power divider with compensation for spurious parameters of a ballast resistor. Radio engineering, N 6, 2011, pp. 59-63) is shown in FIG. 5. The coefficient of direct transmission | S ₂₁ | decreased by 3.9 dB (2.46 times). Frequency dependences of the parameter | S ₂₃ | shifted to the high-frequency region at 380 MHz and were largely outside the considered operating frequency range. The matching characteristics are so unsatisfactory that they do not allow the use of this concept to describe them. Presented in FIG. 5 results show the irrationality of using such a device in engineering practice.

Frequency dependences of the technical characteristics of the proposed power divider using a homogeneous transmission line with each loss of a rectangular shape with the same dimensions 4 × 8 mm ² and an area of 32 mm ² , divided into two by a metallized conductive strip with a short-circuited corrective input and connected to it, for each ballast resistor a cable with a length of less than a quarter of the wavelength of the central frequency of the working range with inductive input resistance (Fig. 3) is shown in Fig. 6. The coefficient of direct transmission | S ₂₁ | at the central frequency of the operating range decreased by 0.98 dB, the unevenness of its frequency dependence in the frequency band 0.8 ... 1.2 GHz increased to 0.67 dB. Decoupling parameter | S ₂₃ | at the central frequency, it decreased to a value acceptable to practice 36.6 dB, the passband for this parameter was 700 MHz, i.e. expanded by about 450 MHz relative to the original idealized version of the device (Fig. 4).

The minimum value of КCBH ₁ = 1.59 at the center frequency of the range f ₀ = 1000 MHz, the input matching band at the level of КCBH ₁ = 1.75 is 309.4 MHz. The minimum value of VSWR is _2.3 = 1.17 at a frequency of 660 MHz, the output matching band is shifted to the lower frequency region, its width exceeds 800 MHz. The obtained technical characteristics of the device are not high enough, however, when comparing them with the characteristics of a power divider — a prototype with ballast resistors of the same size 4 × 8 mm ² and an area of 32 mm ² (Fig. 5), their significant improvement becomes obvious, which allows us to recommend the proposed power divider for use in real microwave equipment.

(обозначения приведены выше).As indicated, the parasitic capacitance of each ballast resistor, made in the form of a segment of a homogeneous transmission line with rectangular losses, is distributed evenly along its length, and therefore, for its full compensation, it is necessary to use an additional short-circuited loop also with an inductive input resistance connected to each output arm of the divider power. The length of this loop is determined from the relation

(designations are given above).

The frequency dependences of the technical characteristics of the proposed power divider with the introduction of additional short-circuited loops connected to each output arm are shown in FIG. 7. A significant improvement in the symmetry of all frequency dependences and the correspondence of their maximum for | S ₂₃ | and minimum values for the VSWR for the center frequency of the range ƒ ₀ = 1000 MHz.

Direct transmission ratio | S ₂₁ | increased by 0.16 dB, the unevenness of its frequency dependence in the frequency band of 0.8 ... 1.2 GHz was 0.83 dB, which is 0.15 dB more than for the variant of FIG. 1. Decoupling parameter | S ₂₃ | equal to 37.4 dB, i.e. 0.75 dB higher than for the embodiment of Fig. 1, the bandwidth of this parameter at a level of -25 dB exceeds 800 MHz, although it is slightly shifted to the lower frequency region (compare it with the value of 248.6 MHz for the power divider prototype with idealized ballast point resistors).

The minimum values of KCBH ₁ = 1.19, VSWR _2.3 = 1.136 correspond to the center frequency of the operating range, the matching band for the level of KCBH ₁ = VSWR _2.3 = 1.5 is equal to 335 MHz at the input, 374 MHz at the outputs.

Thus, the technical result of the invention is to improve matching on the inputs and outputs of the power divider when using ballast resistors with an area equal to or greater than 32 mm ² .

Claims (6)

1. A power divider comprising an input arm connected through a splitter of quarter-wave segments of the transmission line to the output arms, between which ballast resistors are included, the connection of which forms a convex polygon figure, characterized in that each of the ballast resistors is made in the form of a segment of a uniform transmission line with losses of a rectangular shape, divided in half by a metallized conductive strip with a width equal to the width of a short-circuited loop inserted and connected to it with a length less than a quarter of the wavelength of the center frequency of the operating range. 2. The power divider according to claim 1, characterized in that additional short-circuited loops are connected to it, connected to each output arm of the power divider, with a length determined from the relation:

, where λ ₀ is the wavelength in the power divider at the center frequency of the operating range;

- input resistance of the branch of the output arm of the power divider composed of a ballast resistor with parameters Z _R ,

,

and a short-circuit loop with input impedance Z _VHSh1 = jρ _Ш1 tgθ _Ш1 ,

;

,

- wave resistance of short-circuited loops.

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