CN101777687B - Anti-phase microwave power divider with arbitrary power distribution ratio - Google Patents

Abstract

The invention relates to an anti-phase microwave power divider with arbitrary power distribution ratio. The length of a work wave is lambda; the divider has a parallel strip line, wherein the width of two arms of the strip line is as the same as each other, the depth of the strip line is h, and the characteristic impedance is Z0; public metal earth is inserted into a microwave substrate at the h/2 of the depth of one side of the parallel strip line, wherein the inserting depth is l1; a back-to-back symmetrical micro strip pair with the length of l1 and the same width of the arm is formed; the width of the arm corresponding to public earth is changed to form into an asymmetric micro strip pair with the length of lambda/4 and the different lengths of the two arms; the parallel strip line terminal lead input port with the depth of h and the asymmetric micro strip lead two output ports with the depth of h/2 respectively have output power of P2 and P3 and arbitrary power distribution ratios of 1: K2, wherein the K2 equals to1, 2, 3... ; and the characteristic impedance corresponding to the asymmetric micro strip pair is respectively as follows: the public earth is provided with a fold line-shaped gap corresponding to the output end, and the symmetric center of the gap is inserted into the isolation resistance, wherein the vertical distance from the isolation resistance to the output port is as the same as the inserting depth. The divider has the advantages that the anti-phase belt width is wide, can design different arm widths of the asymmetric micro strip pair to obtain two powder distributions with arbitrary power ratio, and has good isolation and small power dissipation.

Description

A kind of anti-phase microwave power splitter with any power-division ratios

Technical field

The present invention relates to microwave power divider, relate in particular to a kind of anti-phase microwave power splitter with any power-division ratios.

Background technology

Microwave power distributor is a kind of multiport microwave network that input microwave signal power is divided into equal or unequal several roads power stage, is widely used in microwave and communication system.According to differing of two output ports, power splitter is divided into homophase distribution type and anti-phase distribution type.In nearest decades, be to the theoretical research of homophase power splitter or design has all obtained a lot of achievements, wherein with Wilkinson power splitter typical case the most.And anti-phase power splitter has been realized balance/difference channel, very extensive and effective application prospect is arranged aspect the microwave circuit performance improving.Past, the most frequently used method for designing was exactly to use the delay unit of 180 ° of electrical length, such as hybrid ring in order to obtain opposite phase characteristic at two output ports.But the anti-phase characteristic of this class device is very responsive to frequency change, causes smaller bandwidth.Recently, a lot of researchers have developed some and have utilized the anti-phase power splitter of realizing such as slotted line, coplanar striplines (CPS) isoequilibrium formula transmission line.As everyone knows, intrinsic anti-phase characteristic between balanced type transmission line two bands can be used for designing the power splitter that has anti-phase characteristic in broad frequency range.Yet, L.Fan and K.Chang mention CPS and are difficult to realize Low ESR in " 180 ° of out-of-phase power of A divider usingasymmetrical coplanar stripline ", characteristic impedance be generally 80 Ω and more than, thereby have to match in this class design middle port impedance, and in order to obtain the port Impedance of 50 required Ω of most of microwave telecommunication systems, just need to increase an impedance transformer, this will increase system dimension greatly, also having limited simultaneously the bandwidth of operation of this class power splitter, only is 13%.And another kind of balanced type transmission line---parallel strips is easy to realize to input, the characteristic impedance of output 50 Ω, and these characteristics have caused microwave circuits person's extensive concern, and existing design comprises low pass filter, anti-phase power splitter.But up to the present, the researcher still focuses on the anti-phase power splitter of the five equilibrium that utilizes the balanced type transmission line design, and has no report about the design of anti-phase microwave power splitter with any power-division ratios in existing document.

Summary of the invention

The object of the invention is to overcome the deficiency of existing anti-phase microwave power splitter, a kind of anti-phase microwave power splitter with any power-division ratios that provides anti-phase characteristic with broad frequency range and power output to distribute arbitrarily.This power splitter is implemented by following technical proposals:

Described microwave power distributor, operation wavelength is λ, it is that h, characteristic impedance are Z that wide identical, the thickness of one or two arm is arranged ₀Parallel strips, insert public metal ground at the microwave-medium substrate at described parallel strips one side h/2 thickness place, insertion depth is l ₁, shape is grown into l ₁, the wide identical back-to-back symmetry of two arms little be with right, change wide corresponding to the arm on public metal ground, shape grow into λ/4, two arms wide not identical back-to-back asymmetric little be with right; Thickness is that the parallel band line end of h is drawn input port, thickness be asymmetric little band of h/2 to drawing two output ports, the power output of two output ports is respectively P ₂, P ₃, this P ₂, P ₃Any merit proportion by subtraction be 1: K ², K wherein ²=1,2,3 Described asymmetric little band is respectively corresponding characteristic impedance:

$Z_2^{\&prime;}=Z_0\sqrt{\frac{1}{(1+K^2)K}},$ ${\mathrm{<figure-callout\; id="3"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_3^{\&prime;}=Z_0\sqrt{\frac{{\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^3}{1+{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^2}};$

Described public metal ground is provided with a fold-line-shaped slit corresponding to the output end position place, and this symmetrical centre place, slit embeds isolation resistance, its resistance

Isolation resistance R is to the vertical range l of output port ₃Identical with described insertion depth, i.e. l ₃=l ₁

The further design of described power splitter is that described insertion depth is l ₁=λ/50～λ/30.

The further design of described power splitter is, in the timesharing of the non-grade of power output, needs the characteristic impedance of access λ/4 impedance transducers to be respectively

Power splitter of the present invention be by the public metal ground in the middle of the microwave-medium substrate with parallel strips be divided into back-to-back difference little be with right, can guarantee that power splitter has the anti-phase characteristic of the frequency limitation of not being subjected in theory, so in the invention design, need not to consider phase bandwidth.The thickness on public metal ground can be ignored, this moment parallel strips and back-to-back little band to need not to change, simplified circuit design.Power splitter encourages at input port, and the power output of two output ports is P ₂, P ₃, design the power output of an output port and be the K of another output port power output ²Doubly, such as P ₃=K ²P ₂, can obtain required power ratio by adjusting asymmetric little band to separately characteristic impedance.The present invention produces following beneficial effect thus:

1. the power splitter among the present invention has the anti-phase characteristic of broad frequency range, can design arbitrarily power-division ratios.Impedance by changing microstrip line and the resistance of isolation resistance, and keep corresponding electrical length can obtain the power division of any power ratio of two-way, and standing-wave ratio, isolation are good, and power loss is little.

2. the power divider structure among the present invention is simple, is easy to realize.Utilized parallel strips as 180 ° of phase differences of balanced type transmission line line-to-line, the metal covering that in the middle of parallel strips, inserts, parallel strips be divided into identical back-to-back difference little be with right, in the situation of the delay unit that does not use 180 ° of electrical length, obtained good phase bandwidth, reduced the volume of circuit, reduced the complexity of circuit, be convenient to be integrated in microwave circuit and the system.

3. the public metal of the power splitter among the present invention ground is opened a slit and is embedded isolation resistance R at nearly output, the slit is designed to be folded to the broken line of output in the position of isolation resistance, prolong the distance between slit and the output, reduced the impact of slit on two outputs.

Description of drawings

Fig. 1 is the structural representation of power splitter one embodiment of the present invention.

Fig. 2 is the top layer circuit diagram of power splitter shown in Figure 1.

Fig. 3 is the structural representation of the intermediate metal layer of power splitter shown in Figure 1.

Fig. 4 is the bottom circuit diagram of power splitter shown in Figure 1.

Fig. 5 is the structural representation of power splitter A-A section shown in Figure 1.

Fig. 6 is S parameters simulation and the test comparison figure of power splitter shown in Figure 1.

Fig. 7 is the output port phase difference simulate and test figure of power splitter shown in Figure 1.

When Fig. 8 is the excitation of strange mould, power splitter upper arm 72 shown in Figure 1,82 equivalent circuit diagram.

When Fig. 9 is the excitation of strange mould, power splitter upper arm 73 shown in Figure 1,83 equivalent circuit diagram.

When Figure 10 is the excitation of even mould, power splitter upper arm 72 shown in Figure 1,82 equivalent circuit diagram.

When Figure 11 is the excitation of even mould, power splitter upper arm 73 shown in Figure 1,83 equivalent circuit diagram.

When Figure 12 is the excitation of even mould, power splitter upper arm 72 shown in Figure 1,82 simple equivalent circuit figure.

When Figure 13 is the excitation of even mould, power splitter upper arm 73 shown in Figure 1,83 simple equivalent circuit figure.

Embodiment

The present invention is further detailed explanation below in conjunction with accompanying drawing, but the invention is not restricted to following embodiment.

Embodiment

Contrast Fig. 1, power splitter of the present invention adopts a parallel strips 4 (being formed by arm 42, arm 43), and the characteristic impedance of this parallel strips is Z ₀, thickness is h, the wide w that is all mutually of arm ₁In the centre of parallel strips 4, the public metal ground 6 that namely inserts on the microwave-medium substrate 5 at h/2 thickness place, insertion depth l ₁Edge take metal ground 6 makes parallel strips 4 right sides be divided into length as l as the boundary ₁, the wide w that is all of arm ₁The little band of back-to-back difference that other parameters also are equal to fully is to being that symmetrical little band is to 7.Form symmetrical little band 7 two arms 72, arm 73 are formed upper strata microstrip line and lower floor's microstrip lines with metal ground 6 respectively).According to power-division ratios and by change arm wide w corresponding to public metal ground to the 7 asymmetric little bands that link to each other to 8 with the little band of symmetry ₁, make underarm on it wide inconsistent and form, the concrete structure that its arm is wide and parameter ask for an interview accompanying drawing 1～4 and below correspondence describe.Asymmetric little band is 1/4 operation wavelength to little belt length of 8.Equally, little band forms the upper strata microstrip line to 8 arm 82 with metal ground 6, and arm 83 forms lower floor's microstrip line with metal ground 6.The top-level metallic arm of power splitter, underlying metal arm, microwave-medium substrate 5 (being divided into publicly two-layer up and down) and public metal ground 6 form five-layer structure like this, see accompanying drawing 5.Thickness is that the parallel band line end (being the end that arm 42 and arm 43 cause side) of h is drawn input port 1, thickness is that the microstrip line of h/2 is drawn respectively output port 2 and output port 3 (end that namely causes side by arm 2a, arm 3a respectively consists of with public metal ground 6), and the power output of this two output port is respectively P ₂, P ₃, establish P ₂, P ₃Any merit proportion by subtraction be 1: K ², K wherein ²=1,2,3 ..., described asymmetric little band is to the long λ of 8 corresponding microstrip lines/4, and λ is operation wavelength, and corresponding characteristic impedance is respectively:

$Z_2^{\&prime;}=Z_0\sqrt{\frac{1}{(1+K^2)K}},$ ${\mathrm{<figure-callout\; id="3"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_3^{\&prime;}=Z_0\sqrt{\frac{{\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^3}{1+{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^2}}.$

The public metal of the present invention ground 6 is provided with a fold-line-shaped slit 61 corresponding to the output end position place, and this symmetrical centre place, slit embeds isolation resistance 9, and resistance is R, Isolation resistance 9 is to output port 2,3 vertical range l ₃Identical with described insertion depth, i.e. l ₃=l ₁

Power in the situation of five equilibrium, does not need two 1/4 wavelength impedance transducer 2b, 3b, and terminate load is changed, and the characteristic impedance of this impedance transducer is respectively

The timesharing such as power then need not impedance transformation.

In the present embodiment, two output ports 2,3 power-division ratios are set to 1: 2, central task frequency 1.75GHz, the thickness h=1.27mm of parallel strips 4, substrate 5 DIELECTRIC CONSTANT ε _r=6.15, the parallel strips characteristic impedance is Z ₀=50 Ω, arm 42, arm 43 width are w ₁=2.7mm makes the input port lead-out wire.Publicly 6 in parallel strips insertion depth l ₁=2mm (about 1/35 wavelength), namely symmetrical little band is 2mm to 7 length, symmetrical little band equates with arm 42, arm 43 that to arm 72, arm 73 width in 7 therefore little band characteristic impedance is Z ₀/ 2=25 Ω.Asymmetric little band is to the long λ/4=17.28mm of 8 corresponding microstrip lines, and corresponding characteristic impedance is Z ₂'=24.27 Ω, Z ₃'=48.55 Ω, arm 82, arm 83 width are respectively w ₂'=2.6mm, w ₃'=0.78mm.In the slit 61 that width s=1.0mm is opened on public metal ground 6, the isolation resistance 9 at 61 centers, slit, its resistance

According to the specification of existing Chip-R, select R=22 Ω, isolation resistance 9 is to output port 2,3 vertical range l ₃, l1 equates with insertion depth, is 2mm, isolation resistance 9 and the distance of left hand edge (about 1/4 wavelength) d=20.12mm publicly.Because this power splitter is non-five equilibrium output, need two 1/4 wavelength impedance transducers, with terminate load Z ₂, Z ₃Carry out impedance transformation, the microstrip line length of this impedance transducer is λ/4=17.28mm, and characteristic impedance is respectively

Counterpart arm 2b, arm 3b width are respectively w _2b=1.34mm, w _3b=0.65mm.Impedance transducer output port lead-out wire is microstrip line, and characteristic impedance is 50 Ω, and counterpart arm 2a, arm 3a width are w=0.94mm, so that power splitter is easy to be connected with system with other microwave components.

The inventor has carried out actual measurement to the power splitter of this example, at central task frequency 1GHz in the 2.5GHz scope, the Insertion Loss of these power splitter two output ports is lower than 0.32dB, differs 180 ° ± 10 ° at 1.0GHz in the 2.3GHz scope, 1.375GHz to isolation between the 2.5GHz greater than 15dB.Therefore the power splitter in the example of the present invention has 1.375GHz to the 2.3GHz broadband, bandwidth about 50%.And insertion depth l ₁When between 2.5mm～1.5mm (about 1/30～1/50 wavelength), changing, on the result substantially without the impact.The simulation result of this result and method for designing of the present invention reaches the good goodness of fit, sees Fig. 6, relevant parameter simulate and test comparison diagram shown in Figure 7.

Other design parameters such as w in the above-mentioned example power splitter ₁, w ₂', w ₃', w _2b, w _3b, w etc. is the characteristic impedance by correspondence, utilize those skilled in the art all known calculating obtain.

Each characteristic impedance parameter is derived by the parity mode advocate approach in above-described embodiment:

Power splitter encourages at port one, and design port 3 power outputs (are designated as P ₃) (be designated as P for port 2 power outputs ₂) K ²Doubly, i.e. P ₃=K ²P ₂, simultaneously anti-phase in the current requirements constant amplitude on port one same distance place arm 82 and arm 83.For satisfying above condition, arm 83 characteristic impedance values should be the K of arm 82 characteristic impedance values ²Doubly, i.e. Z ₃'=K ²Z ₂'.

A. strange mould excitation

At port 2 and port 3 with the anti-phase current excitation of constant amplitude, i.e. I ₂=-I ₃, this moment is I on the plane publicly ₂, I ₃Image current cancel out each other, so do not have electric current to flow through on the isolation resistance 9, thereby do not have loss, strange mould equivalent electric circuit such as Fig. 8, Fig. 9 of power splitter.When power splitter from the input feed, then will obtain larger power on the high arm of characteristic impedance.

If the terminal of port 2 and port 3 is respectively Z ₂, Z ₃According to the power division requirement, have

|I ₃| ²Z ₃＝K ²|I ₂| ²Z ₂

Thereby

Z ₃＝K ²Z ₂

In addition, asymmetric little band is respectively the arm 82 of 8 1/4 wavelength microstrip line and the input impedance of arm 83

$Z_{\mathrm{in}2}=\frac{{{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2^{\&prime;}}^2}{{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2},$ $Z_{\mathrm{in}3}=\frac{{{\mathrm{<figure-callout\; id="3"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_3^{\&prime;}}^2}{{\mathrm{<figure-callout\; id="3"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_3}$

Be the coupling of realization with parallel strips

Z _in2+Z _in3＝Z ₀

So

$Z_2^{\&prime;}=\sqrt{\frac{Z_0{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2}{1+{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^2}},$ ${\mathrm{<figure-callout\; id="3"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_3^{\&prime;}=\sqrt{\frac{Z_0{Z}_3{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^2}{1+{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^2}}$

In order to obtain required power division, select terminal impedance to be respectively Z ₂=Z ₀/ K, Z ₃=KZ ₀

So ${\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2^{\&prime;}=Z_0\sqrt{\frac{1}{(1+K^2)K}},$ ${\mathrm{<figure-callout\; id="3"\; label="Z"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">Z</figure-callout>}}_3^{\&prime;}=Z_0\sqrt{\frac{{\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^3}{1+{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^2}}.$

B. even mould excitation

On port 2,3 to satisfy I ₂=K ²I ₃Current excitation, then voltage distributes identically on arm 82, the arm 83, signal can't be synthetic to 7 interface in parallel strips 4 and symmetrical little band, so this interface is open circuit in the equivalent electric circuit of Figure 10, Figure 11.L among Figure 10, Figure 11 ₂+ l ₃=λ _g/ 4, l ₃Isolation resistance and terminate load Z ₂, Z ₃Between vertical range, for guaranteeing that distance is λ between isolation resistance and the open end _g/ 4 (is l ₂+ l ₁=λ _g/ 4), with the impedance matching that realizes two output ports and the effective isolation between two-port, thereby

l ₃＝l ₁

Common l ₃Should not select excessively, otherwise can cause the excessive (l of circuit size ₁So l corresponding increase), ₃Getting value principle is to realize circuit minimized in the situation that does not affect output port.

During theory analysis, long l ignores ₃The impedance of transmission line, get the power splitter idol mould equivalent electric circuit of simplification, such as Figure 12, Figure 13.

Isolation resistance 9, its value R Figure 10,11 and Figure 12,13 in be divided into two parts R ₁/ K, KR ₁, satisfy

$\frac{1}{R}=\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HSA00000059684000033.png"\; state="\{\{state\}\}">R</figure-callout>}}_1/K}+\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="KR"\; filenames="HSA00000059684000033.png"\; state="\{\{state\}\}">KR</figure-callout>}}_1}$

Circuit is located short circuit at D and D ' among Figure 12, Figure 13.For realizing isolation and the coupling of output, require R ₁=Z ₀

So

$R=\frac{{\mathrm{KZ}}_0}{{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HSA00000059684000011.png,HSA00000059684000033.png"\; state="\{\{state\}\}">K</figure-callout>}}^2+1}.$

In the situation of five equilibrium, two output ports do not need respectively the impedance transducer of 1/4 wavelength to realize Z to power ₂(Z ₃) and Z ₀Impedance matching, characteristic impedance Z _2b, Z _3bSatisfy

Consideration has the requirement of terminal impedance

${\mathrm{<figure-callout\; id="2b"\; label="Z"\; filenames="HSA00000059684000011.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{2b}=Z_0/\sqrt{K},$ ${\mathrm{<figure-callout\; id="3b"\; label="Z"\; filenames="HSA00000059684000011.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{3b}=\sqrt{K}{Z}_0$

The timesharing such as power then need not conversion, Z ₂(Z ₃) can directly design and Z ₀Impedance matching.

On the whole, the parallel strips of power splitter input port of the present invention provides the anti-phase characteristic in the broad frequency range for output, can design arbitrarily power-division ratios simultaneously.Impedance (realizing by the width that changes each arm) by changing microstrip line and the resistance of isolation resistance, and keep corresponding electrical length can obtain the power division of any power ratio of two-way, and isolation is good, and power loss is little.

Claims (3)

1. anti-phase microwave power splitter with any power-division ratios, operation wavelength is λ, it is that h, characteristic impedance are Z that wide identical, the thickness of one or two arm is arranged ₀Parallel strips, it is characterized in that inserting public metal ground at the microwave-medium substrate at described parallel strips one side h/2 thickness place, insertion depth is l ₁, shape is grown into l ₁, the wide identical back-to-back symmetry of two arms little be with right, change wide corresponding to the arm on public metal ground, shape grow into λ/4, two arms wide not identical and the little band of symmetry to link to each other back-to-back asymmetric little be with right; Thickness is that the parallel band line end of h is drawn input port, thickness be asymmetric little band of h/2 to drawing two output ports, the power output of two output ports is respectively P ₂, P ₃, this P ₂, P ₃Any merit proportion by subtraction be 1: K ², K wherein ²=1,2,3...; Described asymmetric little band is respectively corresponding characteristic impedance:

$Z_2^{\&prime;}=Z_0\sqrt{\frac{1}{(1+K^2)K}},$ $Z_3^{\&prime;}=Z_0\sqrt{\frac{K^3}{1+K^2}};$

Described public metal ground is provided with a fold-line-shaped slit corresponding to the output end position place, and this symmetrical centre place, slit embeds isolation resistance, its resistance

Isolation resistance R is to the vertical range l of output port ₃Identical with described insertion depth, i.e. l ₃=l ₁

2. a kind of anti-phase microwave power splitter with any power-division ratios according to claim 1 is characterized in that described insertion depth is l ₁=λ/50～λ/30.

3. a kind of anti-phase microwave power splitter with any power-division ratios according to claim 2 is characterized in that needing the characteristic impedance of access λ/4 impedance transducers to be respectively in the timesharing of the non-grade of power output

The timesharing such as power then need not impedance transformation.

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