JPS5943001B2 - Band “ro” wave device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a band F wave device that allows the fundamental wave to pass through without attenuation, blocks the second harmonic wave, and absorbs and attenuates the second harmonic wave without reflecting it to the input side. It is related to.

Bandpass filters and low-pass filters, which are commonly used in the past,
Signals in the pass band pass through without being attenuated, but signals in the stop band are reflected from the input ends of these p-wave devices and returned to the input side.

FIG. 1 shows an example of such a conventional P-wave device.

In the figure, 1 and 2 are transmission lines on the input side and output side, respectively.

3°4, 5, and 6 are parallel elements, each of which acts as a capacitance, and 7 and 8°9 are series elements, each of which acts as an inductance.

Therefore, the P-wave device shown in FIG. 1 constitutes a low-pass P-wave device, which allows frequencies below a certain cutoff frequency determined by the values of the respective diapasitances and inductances to pass, and blocks frequencies above that.

In the Oki transducer shown in FIG. 1, its input and output impedances are approximately equal to the nominal impedance within the passband, but are significantly different in the stopband.

Therefore, when such a P-wave device is connected to an amplifier or an oscillator and used, there is a risk that the characteristics of the amplifier or oscillator will be significantly impaired because signals in the stop band will be reflected back.

In order to prevent this phenomenon, an F-wave filter is used that allows passband signals to pass through without attenuation, but prevents stopband signals from being reflected to the input side and is internally absorbed and attenuated. It would be convenient if we could get it.

An object of the present invention is to provide a band P-wave device that allows such a fundamental wave to pass through without attenuation, and internally absorbs and attenuates the second harmonic wave without reflecting it. There is a particular thing.

Examples will be described in detail below.

FIG. 2 is a diagram showing the configuration of an embodiment of the band p-wave device of the present invention.

In the figure, 11 is an input transmission line, 12 is an output transmission line, 13, 14° and 15 are series elements, 16 and 1γ are stubs, 18° and 19 are parallel elements, and 20 and 21 are resistors.

Now, it is assumed that these transmission lines and each element are composed of microstrip lines, and the characteristic impedance of the transmission line 1L12 is Z.

, the portions of elements 13, 14, 15, 16, and 17 are Z.

′, and there is a relation Zo′〉Zo.

Also, the wavelength of the fundamental wave on the microstrip line is λ
g, the series elements 13, 14 and the stub 16,
It is assumed that the lengths of each of the elements 17 and 17 are λg/8, and the lengths of the series element 15 and the parallel elements 18 and 19 are each λg/4.

Therefore, in the configuration of the P-wave device of the present invention, a transmission line having an impedance of Zo is cut in the middle, and a Z wave is applied to that part.

′(Zo′〉Zo)
g/2 is inserted in series, and stubs 16 and 17 each having a length of λg/8 are provided at points separated by λg/8 from the center of the transmission line inserted in series,
More Z.

Z inserted in series with a transmission line having an impedance of

There is an impedance Z at each connection point with a transmission line having an impedance of '.

A resistor 20.21 having a value equal to The unconnected ends of the resistors are grounded.

In FIG. 2, if the ungrounded ends of parallel elements 18 and 19 are A and B, respectively, the lengths of parallel elements 18 and 19 are both λg/4, so the impedance of ends A and B is is also infinite with respect to the fundamental wave.

Therefore, when the connection between the transmission line 11 and the series element 13 is C, the resistor connected between the connection C and the end A does not apply a load to the transmission line 11.

Similarly, when the connection between the transmission line 12 and the series element 14 is D, the resistor 21 connected between the connection and the end A
does not apply any load to the transmission line 12.

The connection point of series element 13, series element 15, and stub 16 is E.
1 If the connection point of the series element 14, the series element 15, and the stub 17 is F, the length of the microstrip line between the connection point E and the connection point F is λg/4, and the series elements 13.14 before and after it are λg/4. The lengths of the stubs 16° and 1γ are equal, and the lengths of the stubs 16° and 1γ are equal. The effects of 16 and 17 cannot cancel each other out.

Also, since the length of the transmission line between the connection point C and the connection point is λg/2 as mentioned above, the impedance of the connection point C and the impedance of the connection point are converted to be equal to each other with respect to the fundamental wave. be done.

From the above relationship, the impedance Z at the connection point C of the transmission line 11.

is the impedance Z at the connection point of the transmission line 12
.

and are matched at the fundamental wave.

Therefore, the P-wave device in FIG. 2 has a passband for the fundamental wave.

On the other hand, if the wavelength of the second harmonic is λS, then the parallel element 18.1
9 has a length of λs/2 for the second harmonic, so both ends A and B are grounded, so the resistance 20
．． 21 are connected between the end A and the connection point C and between the end B and the connection point, respectively, and serve as a load.

Therefore, the transmission lines 11 and 12 have an impedance Z at connection points C and D, respectively.

terminated with

Furthermore, since the lengths of the series element 13 and the stub 16 are λs/4 for the second harmonic wave, the impedance on the side of the series element 13 seen from the connection point C becomes infinite, and therefore the second harmonic wave is transmitted through the transmission line. 11 to the series element 13 side.

The relationship on the side of the series element 14 when viewed from the connection point of the transmission line 12 is exactly the same.

Therefore, the P-wave device shown in FIG. 2 serves as a stop band for the second harmonic.

At this time, the transmission line LL12 has a characteristic impedance Z.

Since the transmission line is terminated at , all the transmitted second harmonic waves are absorbed by the resistors 20 and 21, respectively, and do not return to the transmission line side.

In this way, the P-wave generator shown in Fig. 2 has small attenuation for the fundamental wave, gradually increases the attenuation as the frequency increases, and has an attenuation pole at the double frequency point. Acts as.

In the stopband, the signal component that is blocked because it is terminated by the resistor 20.21 as described above is transferred to the resistor 20.21.
It is possible to realize a mud wave device that is absorbed by the mud wave 21 and does not return to the input side.

In addition, the impedance Z of the transmission line of the P-wave device part.

′ is the impedance Z of the input transmission line.

The impedance Z of the transmission line should be chosen larger outside the passband.

' is the impedance Z of the resistor 2U or 21.

Since the transmission lines 11 and 12 are connected in parallel, the terminal impedance of the transmission lines 11 and 12 should be set to the characteristic impedance Z as much as possible.

This is to bring it closer to .

Furthermore, the structural dimensions of each part of the P-wave device may actually be slightly modified from the structural dimensions of the embodiment shown in FIG. The relationship between the passband and stopband can also be modified to some extent.

In the embodiment shown in FIG. 2, the P-wave device is constructed using a microstrip line, but it goes without saying that the band P-wave device of the present invention can also be realized using other transmission lines, such as coaxial lines.

FIG. 3 shows an example of the performance of the bandpass filter of the present invention realized in this manner.

In this example, the fundamental wave f serves as a passband.

The frequency is approximately 5.5 GHz, and the attenuation pole is located at approximately 11 GHz, which is twice the frequency of the 9.

Furthermore, the fact that signal reflection is small not only in the passband but also in the stopband can be seen from the fact that the voltage standing wave ratio (VSWR) is small over the entire region.

As explained above, according to the band P-wave device of the present invention, it is possible to realize a mud wave device that allows the fundamental wave to pass, blocks the second harmonic wave, and absorbs and attenuates signals of frequencies other than the blocked passband. Therefore, when used in amplifiers, oscillators, etc., the blocked signals do not return to these amplifiers or oscillators and have an adverse effect, providing convenience in circuit configuration.

The band P-wave device of the present invention is particularly suitable when used in combination with an amplifier or an oscillator, but can be used in other general circuit configurations.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a conventional P-wave device, FIG. 2 is a diagram showing the configuration of an embodiment of the band P-wave device of the present invention, and FIG. 3 is a diagram showing the configuration of an embodiment of the band P-wave device of the present invention. FIG. 3 is a diagram showing an example of characteristics. 1...Input side transmission line, 2...Output side transmission line, 3.4, 5, 6...Parallel element, 7,
8.9...Series element, 11...Input side transmission line, 12...Output side transmission line, 13,1
4, 15...Series element, 16.17...
Stub, 18, 19... Parallel element, 20.21
······resistance.

Claims (1)

[Claims] 1 Z in the middle of a transmission line having an impedance of Zo. '(Zo'〉Zo) Length λg/2 (λg is the wavelength of the fundamental wave on the transmission line)
transmission lines are inserted in series, and each point of length λg/8 is placed at a point λg/8 apart from the center of the transmission line inserted in series.
8 stubs were provided, and both ends of the transmission line inserted in series and Z. Z at each connection point with a transmission line having an impedance of A parallel transmission line having an arbitrary impedance of length λg/4 is provided through a resistor having an impedance equal to the impedance, and an end of the parallel transmission line to which the resistor is not connected is grounded. Band F wave device.