JPS6117401B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amplitude equalizer that equalizes amplitude frequency characteristics in a microwave band. Conventionally, the following types of amplitude equalizers have been considered as this type of amplitude equalizer.

(1) Phase synthesis type: as shown in FIG. 1, consisting of a main line 1, a sub line 2, a coupling section 3, 3' attenuating section 4, and a delay section 5. In principle, a part of the signal on the main line is taken out to the sub line 2 at the coupling part 3 and delayed, thereby imparting phase and frequency characteristics. Next, by adding the signal of the sub line 2 having the phase frequency characteristic to the signal of the main line 1 again by the coupling section 3', a ripple-like amplitude frequency characteristic is obtained. The amplitude frequency characteristic of this type of equalizer is periodic, as shown in FIG. As mentioned above, this type of equalizer has the disadvantage that it has a complicated structure and can only equalize periodic amplitude characteristics.

(2) Delay equalizer type: The configuration shown in FIG. 3 consists of a directional coupler section 6 and a line section 7 with increased loss. The longer the delay time per transport, the greater the passing loss, and the greater the line loss, the greater the passing loss. Since the delay equalizer has frequency characteristics of delay, it also has frequency characteristics of amplitude. In a normal delay equalizer, the amplitude frequency characteristics are made smaller by reducing the line loss, but the amplitude frequency characteristics can be increased by increasing the line loss. In this type of amplitude equalizer, in order to make the equalization characteristic variable, the degree of coupling must be made variable or the loss of the line must be made variable, making it difficult to realize a variable portion.

(3) A device using a band-elimination filter: It has a configuration as shown in FIG. 4 and consists of a circulator 8, a band-elimination filter 9, and an attenuator 10. The amplitude frequency characteristic is realized by reflecting a specific frequency by the band-elimination filter 9. The amplitude frequency characteristics of this type of equalizer are shown in FIG.
Although this equalizer can realize a frequency characteristic that is convex upward, it cannot realize a frequency characteristic that is convex downward, so it has a drawback that it cannot equalize a frequency characteristic that is convex upward.

An object of the present invention is to provide an amplitude equalizer for easily equalizing arbitrary waveforms in the microwave band.

The present invention will be explained in detail below.

FIG. 6 shows an embodiment of the present invention, in which 11 is a signal input terminal, 12 is a band-elimination filter, 13 is a circulator, 14 is a band-elimination filter, and 15 is a termination section 16 is an output terminal. The operation of the present amplitude equalizer will be explained with reference to the frequency characteristics (FIG. 7) of the present amplitude equalizer. The microwave signal inputted from the input terminal 11 is subjected to a band-elimination filter 12, which causes a dent in the amplitude at a specific frequency, as shown at A in FIG. The height and width of this recess can be adjusted by adjusting Q _O and Q _L of the band-elimination filter 12. Further, the number of depressions can be increased by connecting band-elimination filters having different resonance frequencies in series. The microwave signal, which has been indented at a particular frequency, then passes through a circulator 13 and enters a band-stop filter 14 . The band-elimination filter 14 blocks a specific frequency and produces a protrusion in the amplitude characteristic as shown in FIG. 7B.
A portion of the microwave that has passed through the band-elimination filter 14 is absorbed by a terminal end 15 made of, for example, a resistor and a shorting plate, and the rest is reflected, passes through the circulator 13, and is output from the output end 16. The height and width of the protrusions can be adjusted by changing Q _O and Q _L of the band-elimination filter 14, and the number of protrusions can be increased by connecting band-elimination filters with different resonance frequencies in series. Furthermore, by adjusting the return loss at the end, the overall level at the output end 16 can be adjusted. Adjustment of this return loss is performed at the terminal section 15.
It can be easily adjusted by adjusting the adjustment screw provided in the or by adjusting the size of the resistance absorber. The amplitude equalizer of the present invention obtains arbitrary amplitude characteristics by adjusting _{Q O} and Q _L of a band-elimination filter _.
An example of a band-stop filter that can easily vary the
Shown in Figures a-c. In Figure 8, 18 is approximately λ/4
19 is a resonator and main line coupling element, and 20 is a microwave absorber for adjusting the loss Q _O of this resonator. The frequency characteristic diagram of this band-elimination filter will be explained using FIG. 9. The approximately λ/4 metal piece 18 is a TEM mode resonator, and by varying the insertion length into the waveguide, it becomes a band-stop filter with variable resonance frequency. However, as it is, the electric field of the main line waveguide is perpendicular to 18 and hardly couples with 18, so the resonance band is very narrow. A coupling element 19 is used to increase the coupling between the main line and the resonator. By inserting 19 into the waveguide, the electromagnetic field within the waveguide is disturbed.
An electric field component parallel to 8 is also generated, and the coupling becomes stronger.
By increasing the insertion length of this coupling element, the characteristics change from B to A in FIG. 9. In addition, by changing the insertion length of the absorber 20, the Q _O of this resonator can be
can be changed, and the characteristics change from B to C in FIG. As explained above, by connecting a band-elimination filter and a circulator connected to one end of the band-elimination filter in series, arbitrary frequency characteristics can be easily achieved in the microwave band. It is possible to construct an amplitude equalizer that can equalize any waveform of .

The above has been described for the case where one circulator is used, but it can also be applied to the case where two or more circulators are connected in series, or when an isolator is connected between the band-elimination filter 12 and the circulator 13. In this case, an amplitude equalizer can be constructed in the same way.

[Brief explanation of the drawing]

Figure 1 is an example of a block diagram of a conventional phase synthesis type amplitude equalizer, Figure 2 is the amplitude frequency characteristic of the amplitude equalizer in Figure 1, and Figure 3 is the amplitude of a conventional delay equalizer type. An example of an equalizer, FIG. 4 is an example of an amplitude equalizer using a conventional band-stop filter, FIG. 5 is an amplitude frequency characteristic of the amplitude equalizer shown in FIG. One embodiment, FIG. 7 shows the amplitude frequency characteristics of the amplitude equalizer of the present invention, and FIG. 8 shows an elevational view, a side view, and a front view of an example of a band-stop filter used in the present invention. 9 shows the amplitude frequency characteristics of the band-elimination filter shown in FIG. 8. In the figure, 11 is a signal input terminal, 12 and 14 are band-elimination filters, 13 is a circulator, 15 is a termination section, and 16 is an output terminal.

Claims (1)

[Claims] 1. A circulator having first, second, and third output terminals, and a first band-elimination filter having one end coupled to an input signal terminal and the other end coupled to the first terminal. a second band-stop filter having one end coupled to the second terminal; and a termination section coupled to the other end of the second band-stop filter. Equalizer. 2. The amplitude equalizer according to claim 1, wherein at least one of the first and second band-elimination filters includes a microwave absorber. 3. The amplitude equalizer according to claim 1 or 2, characterized in that an isolator is provided between the first terminal and the other end of the first band-elimination filter.