KR100603615B1 - Broadband Microstrip Balun - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a broadband microstrip balun.

2. The technical problem to be solved by the invention

The present invention uses a 90-degree phase difference coupler and a microstrip line using a broadband in-phase power divider and a dual-line coaxial line, making it easy to manufacture and stably guaranteeing the same characteristics even when manufacturing a plurality of baluns. The purpose is to provide a strip balun.

3. Summary of Solution to Invention

The present invention is a circuit for separating an input signal into a signal having the same power and 180 degrees out of phase, or conversely combining a signal having the same power and 180 degrees out of phase, the signal received from the outside having the same delay time In-phase equipotential power distribution means for separating and outputting the signals of phase and intensity; First coupling means for receiving and outputting one output signal of the in-phase equipotential power distribution means; And second coupling means for receiving another output signal of the in-phase equipotential power distribution means and outputting a signal having the same delay time, 180 degrees phase difference, and equipotential power as the output signal of the first coupling means.

4. Important uses of the invention

The invention is used in balun systems and the like.

Balun, Balun, Microstrip Balun

Description

Wideband Microstrip Balun             

1 is a balun configuration diagram using a conventional core and wire wire

2 is a balun configuration diagram using a coaxial line in a conventional microstrip substrate,

3 is a configuration diagram of an embodiment of a broadband microstrip balun according to the present invention;

4 is a detailed configuration diagram of an embodiment of a first coupler according to the present invention;

5 is a detailed configuration diagram of an embodiment of a second coupler according to the present invention.

* Explanation of symbols for the main parts of the drawings

10: 3-dB Equal-Phase Power Divider

20: first coupler 30: second coupler

40: 90 ° phase difference equipotential coupler (3-dB 90 ° Phase Coupler)

21: Open Circuit 31: Short Circuit (Open Circuit)

In: Input Terminal Coup: Coupler Terminal

Thr: Through Terminal Iso: Isolation Terminal

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadband microstrip balun, and more particularly, to separately output a signal of one input terminal into two output terminals having the same delay time and having a 180 degree phase difference of the same intensity, or The present invention relates to a wideband microstrip balun that outputs two input signals having a 180 degree phase difference of the same intensity in the opposite direction and having the same delay time and combining the signals into one output.

Balun refers to a circuit / structure that converts a balanced signal into an unbalanced signal. Or when the reverse conversion function is also called Balun (Balun). The balun is a device that can operate even when the input and output are switched.

Hereinafter, a description will be given based on a balun of one input terminal and two output terminals.

The balun is mainly used for push-pull power amplifiers or two symmetrical antenna matching. The basic operation of the existing balun was to simultaneously implement isoelectric power distribution and 180 degree phase difference in one device, and was mainly used at low frequencies below the VHF band.

1 is a configuration diagram of a balun using a core and a wire wire according to the related art.

A conventional balun that is generally used is a balun composed of a core and a plurality of windings, which sets an impedance match between an input and an output and a frequency band used according to the characteristics of the core and the ratio of the winding wound on the core.

As shown in FIG. 1, a balun using a core and a wire wire according to the related art is composed of a core 101 and two windings (first winding and second winding) wound around the core 101.

The first winding and the second winding are composed of input portions 102 and 104 and output portions 103 and 105.

The first winding and the second winding may be woven together as shown in FIG. 1, but may be manufactured separately from each other by desired characteristics.

When a signal is supplied to the input portion 102 of the first winding, the output portion 103 is grounded, and the input portion 104 and the output portion 105 of the second winding have a constant power ratio by the number of turns of the core. It outputs a signal having a 180 degree phase difference.

That is, the input portion 102 of the first winding becomes one input signal terminal, and the input portion 104 and the output portion 105 of the second winding become two output terminals having a 180 degree phase difference.

However, the conventional balun using the core and the winding has a problem that it is difficult to guarantee the same characteristics due to the nonuniformity of the winding spacing and the characteristic difference depending on the core material in the VHF band or more.

On the other hand, a conventional balun having a broadband characteristic may be a balun of a strip line structure. The balun of the strip line has a structure that can be used stably even in the VHF band or more, but there is inconvenience in manufacturing and using since the substrate must be used together with the front and rear surfaces.

In particular, the microstrip balun is very difficult to configure two output terminals of equal power of 180 degrees phase difference with the same delay time in one input line due to the characteristics of the circuit.

2 is a balun configuration diagram using a coaxial line in a conventional microstrip substrate.

As shown in FIG. 2, a balun using a coaxial line in a conventional microstrip substrate is implemented by simultaneously using a coaxial line and a substrate line existing in a microstrip substrate on a microstrip substrate. It consists of one input transmission line 203, two output transmission lines 204 and 205, and a coaxial line 201.

The input transmission line 203 is connected to the coaxial line centerline 202 existing at the center of the coaxial line 201 to transmit a signal. The signal of the center line 202 of the coaxial line is connected to the microstrip output transmission line 205 to output a signal.

In addition, the outer edge of the coaxial line 201 is connected to the microstrip output transmission line 204 to output a signal. This is because when the AC signal is supplied to the center line 202 of the coaxial line, the outer skin of the coaxial line uses the characteristics of the ultra-high frequency signal generated in the reverse direction of the center line of the coaxial line.

The ground hole 206 is for recognizing the transmission signal that the lines of the ultra-high frequency line and the coaxial line are shorted at a length half a wavelength away from the microstrip output transmission lines 204 and 205.

Such a balun using a coaxial line in a conventional microstrip substrate has a stable balun characteristic, but has a problem of having a narrow band characteristic.

The present invention has been proposed to solve the above problems, by using a 90-degree phase difference coupler and a microstrip line using a broadband in-phase power divider and a dual line coaxial line, even when manufacturing a large number of baluns It is an object of the present invention to provide a microstrip balun with a wideband characteristic which reliably guarantees the same characteristic.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The present invention for achieving the above object, in the circuit for separating the input signal into a signal having the same power and 180 degrees phase difference, or conversely to combine a signal having the same power and 180 degrees phase difference, the signal received from the outside In-phase equipotential power distribution means for dividing the signal into signals of the same phase and intensity with the same delay time; First coupling means for receiving and outputting one output signal of the in-phase equipotential power distribution means; And second coupling means for receiving another output signal of the in-phase equipotential power distribution means and outputting a signal having the same delay time, 180 degrees phase difference, and equipotential power as the output signal of the first coupling means. It features.

In addition, the present invention provides a circuit for combining a signal having the same power and 180 degrees phase difference, the first coupling means for outputting a signal received from the outside with a constant delay time; A second signal which receives a signal having the same power as the input signal of the first coupling means and is 180 degrees out of phase, and converts the signal into a signal having the same delay, power, and phase as the output signal of the first coupling means; Coupling means; And an in-phase equipotential coupling means for coupling the output signals of the first coupling means and the second coupling means.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As described above, the balun can be applied to one input and two outputs, or vice versa, to the two inputs and one output in the same manner. We will refer to the circuit of two output signals (signals of balanced circuits) having a 180 degree phase difference in power. It is apparent to those skilled in the art that two input signals (a signal of balanced circuit) and one output signal (a signal of unbalanced circuit) can be understood as the reverse operation.

3 is a configuration diagram of an embodiment of a broadband microstrip balun according to the present invention.

As shown in FIG. 3, the broadband microstrip balun according to the present invention receives a signal from an external unbalanced circuit using one microstrip line and delays the input signal by using two microstrip lines. The first and second output signals are output to an external balanced circuit by distributing the signals by equal power having a phase difference of 180 degrees with time.

In more detail, the broadband microstrip balun according to the present invention converts an input signal input from an external unbalance circuit into two signals (first split signal, second split signal) having the same delay time, the same phase, and the same intensity. Outputting a 3-dB Equal-Phase Power Divider (10), a first output signal having a 90-degree phase difference from the first divided signal received from the in-phase equipotential power divider (10) 90 degrees out of phase difference with the 2nd distribution signal input from the 1st coupler 20 and the in-phase equipotential power divider 10, and the 2nd output of the same delay time, 180 degree phase difference, and equipotential as the said 1st output signal And a second coupler 30 for outputting a signal.

4 is a detailed configuration diagram of an embodiment of a first coupler according to the present invention.

As shown in FIG. 4, the first coupler according to the present invention includes a 90 degree phase difference equipotential coupler 40 and an open line 21.

Here, the 90-degree phase difference equipotential coupler 40 is connected from the in-phase equipotential divider 10 to the microstrip line through the input terminal In to receive the first divided signal, the coupling terminal Coup, and the through Terminals Thr are connected to the open lines 21 to totally reflect the input signal, and output the first output signal to the isolated terminal Iso.

5 is a detailed configuration diagram of an embodiment of a second coupler according to the present invention.

As shown in FIG. 5, the second coupler according to the present invention includes a 90 degree phase difference equipotential coupler 40 and a shorting line 31.

Here, the 90-degree phase difference equipotential power coupler 40 of the second coupler is connected to the in-phase equipotential power divider 10 and the input terminal In through a micro strip line to receive a second divided signal, and the coupling terminal Coup ) And a through terminal Thr are connected to the short-circuit line 31 so as to totally reflect the input signal, and output a second output signal having a magnitude different from that of the first output signal by 180 degrees to the isolated terminal Iso.

Here, the 90-degree phase difference equal power coupler 40 will be described in detail.

The 90 degree phase difference isoelectric coupler 40 according to the present invention is a 90 degree phase difference iso power coupler using a dual line coaxial line, which is smaller in size than the branch line coupler representing the 90 degree phase difference iso power coupler among microwaves. Compared to the coupler and strip line coupler, the microstrip is a common process to implement.

The dual line coaxial line used in the present invention has two centerlines twisted together compared to one centerline of a general coaxial line, so that a high coupling relationship between two centerlines can be maintained, so that a wide band for one input can be obtained. Two distributions (coupling terminal Coup, through terminal Thr) to the same power are possible.

By cutting and attaching the dual-line coaxial line to a suitable length on the microstrip substrate, the power coupler such as a 90-degree phase difference can be realized, and thus, it is simpler than other methods described above and can be easily implemented in the microstrip. The general operation of the 90 degree phase difference equipotential power coupler 40 using the double line coaxial line according to the present invention is the same as that of a conventional conventional branch line coupler.

The structure and operation of the 90 degree phase difference equal power coupler 40 using the double line coaxial line according to the present invention will be described in detail as follows.

 The dual-line coaxial line has two center wire lines, an outer line, an insulator (between the outer line and the inner line) and an inner line. When the double-line coaxial line is cut to the appropriate length and attached to the board, the two center wire lines have two connections on the input side and two improvements on the output side, resulting in four connection points.

One line on the input side becomes the input terminal (In), the other becomes the coupler terminal (Coup), and the line existing on the connection line directly with the line on the input side of the two lines on the output side is the through terminal (Thr), The other line becomes the isolation terminal Iso.

The coupler terminal Coup and the through terminal Thr are distributed with the same power for the input at a desired frequency according to the length of the double line coaxial line, and the isolation terminal Iso has no output signal.

In addition, the coupler terminal Coup and the through terminal Thr naturally have a 90 degree phase difference. Here, when a load having the same characteristic is connected to the through terminal Thr and the coupler terminal Coup, the signal is not output to the input terminal In, but the signal is output to the isolation terminal Iso.

If the load is a device in which there is no attenuation of the signal due to a short circuit or opening, the signal input to the dual line coaxial line is completely output to the isolation terminal Iso without loss. At this time, when the load is short-circuit and open, signals are output with a 180 degree phase difference due to the characteristics of the ultra-high frequency.

Hereinafter, the operation of the present invention will be described in detail.

The in-phase equipotential divider 10 separates and outputs a signal received from the outside through a microstrip line into two microstrip transmission lines (a first split signal and a second split signal).

The first distribution signal, which is one of the output signals of the wideband in-phase equipotential power splitter 10, is input to an input terminal In of the 90 degree phase difference equal power coupler 40 of the first coupler 20, thereby providing a dual line coaxial line. Half of the input power is output to the coupling terminal Coup of the 90-degree phase difference isoelectric coupler 40 and half of the input power is output to the through terminal Thr.

The open line 21 connected to the coupling terminal Coup of the 90 degree phase difference isoelectric power coupler 40 of the first coupler 20 and the open line 21 connected to the through terminal Thr have the same length. The signal supplied to the coupling terminal Coup and the through terminal Thr is totally reflected.

The signal totally reflected from the open line 21 is not transmitted to the input terminal In of the 90-degree phase difference equipotential coupler 40, but is first transmitted to the isolation terminal Iso of the 90-degree phase difference equipotential coupler 40. The output signal is output.

The second distribution signal, which is another output signal of the broadband in-phase equipotential divider 10, is input to the input terminal In of the 90 degree phase difference equipotential coupler 40 of the second coupler 30 via the microstrip transmission line. do.

The 90 degree phase difference equipotential coupler 40 using the double line coaxial line of the second coupler is a half degree of input power to the coupling terminal Coup and the 90 degree phase difference equipotential coupler 40 using the double line coaxial line in the first coupler. Half of the input power is output to the through terminal Thr.

The short circuit 31 connected to the coupling terminal Coup of the 90 degree phase difference equipotential coupler 40 of the second coupler and the short circuit 31 connected to the through terminal Thr have the same length, The signal supplied to Coup and through terminal Thr is totally reflected.

The signal totally reflected by the short-circuit line 31 is not transmitted to the input terminal In of the 90 degree phase difference power coupler 40 using the double line coaxial line, but the second output signal is output to the isolation terminal Iso.

As a result, the phase difference between the first output signal and the second output signal is 180 degrees due to the total reflection by the open line and the short line in the two couplers 20 and 30.

Since there is no different path between the two paths except for the open line and the short line which are totally reflected in the 90-degree phase difference isoelectric coupler 40 using the double line coaxial line, the strength of the signal provided through the two paths is the same.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

In the present invention as described above, the signal of one input terminal is divided into two output terminals having the same delay time and having a 180 degree phase difference of the same intensity, or an output signal having two 180 degree phase differences of the same intensity In a balun device that combines and outputs a signal with one output with the same delay time, the balun has a large characteristic change due to the balun fabrication on the microstrip substrate over the VHF band and is easy to manufacture, and has a wideband characteristic. Can be provided.

Claims (7)

A circuit for separating an input signal into signals having the same power and 180 degrees out of phase, or conversely combining signals having the same power and 180 degrees out of phase, In-phase equipotential power distribution means for dividing and outputting a signal received from the outside into a signal having the same phase and intensity with the same delay time; First coupling means for receiving and outputting one output signal of the in-phase equipotential power distribution means; And Second coupling means for receiving another output signal of the in-phase equipotential power distribution means and outputting a signal having a delay time, a 180 degree phase difference, and an equipotential power equal to the output signal of the first coupling means; Broadband microstrip balun comprising a. The method of claim 1, The first coupling means and the second coupling means, 90 degree phase difference equal power coupling means using double line coaxial line Broadband microstrip balun comprising a. The method of claim 2, The first coupling means, An open line connected to the 90 degree phase difference power coupling means Broadband microstrip balun that includes more. The method of claim 2 or 3, The second coupling means, Short circuit connected to said 90 degree phase difference equal power coupling means Broadband microstrip balun that includes more. The method of claim 2, The double line coaxial line, Broadband microstrip balun characterized in that two coaxial lines are twisted together for signal distribution over a wideband. In a circuit that combines signals with the same power and a 180 degree phase difference, First coupling means for outputting a signal received from the outside with a predetermined delay time; A second signal which receives a signal having the same power as the input signal of the first coupling means and is 180 degrees out of phase, and converts the signal into a signal having the same delay, power, and phase as the output signal of the first coupling means; Coupling means; And In-phase equipotential coupling means for coupling the output signals of the first coupling means and the second coupling means Broadband microstrip balun comprising a. The method of claim 6, The first coupling means and the second coupling means, 90-degree phase difference equipotential coupling means using dual line coaxial line Broadband microstrip balun comprising a.

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