KR100358975B1 - Low-Loss and Broadband Non-Radiative Dielectric(NRD) Waveguide Circulator - Google Patents

Abstract

The present invention relates to a circulator having a broadband characteristic applied to an isolator, an injection synchronous amplifier, a modulator, etc. using an NRD guide. In Example 1, a permanent magnet was used and a mode sprayer capable of suppressing the unnecessary mode was inserted in order to obtain low loss characteristics. In Example 2, NRD lines, which are ports of circulators using NRD guides, were stepped to obtain broadband characteristics.

Description

Low Loss and Broadband Non-Radiative Dielectric (NRD) Waveguide Circulator}

Non-radial dielectric waveguides (NRD guides), which are millimeter wave integrated circuits, have low loss and non-radioactive characteristics.

The NRD guide circuit maintains the upper and lower conductor plates at intervals less than half of the wavelength with respect to the frequency to be used, and arranges dielectric lines having the same height and the same width as the upper and lower conductor plates between the upper and lower conductor plates. Configure

The circulator, a representative irreversible circuit element in the millimeter wave band, is an essential circuit element for applications such as an isolator, an injection synchronous amplifier, and a modulator.

However, the circulator may have an insertion loss of about 4-5 dB due to the unnecessary mode (TE, LSE mode) generated between the ferrite resonator and the NRD guide line, so that it is difficult to obtain desired output characteristics.

In addition, since most bandwidths having an isolation of 20 dB or more are only about 1 GHz, a modulator may be difficult to detect a desired signal due to a narrow area that may include higher order components of the signal.

Therefore, the circulator using the permanent magnet for NRD guide as shown in Figure 2 has a problem that can not maintain the characteristics of the low loss, which is the advantage of the NRD guide, there is a lot of points that are insufficient to communicate a lot of information in the wider band of modern times.

An object of the present invention is to propose a circulator using permanent magnets, which maintains the low loss of the above-described NRD guide and has broadband characteristics.

In other words, by inserting the mode compressor (10, 11, 12) in the circulator using a permanent magnet to reduce the loss to maintain the low loss of the NRD guide, and to increase the bandwidth of the region having more than 20dB block It is characterized by narrowing the width of (13, 14, 15) to a step shape.

In the first embodiment of the present invention, the permanent magnets 6 are mounted on the upper and lower conductor plates 1 and 2, and the ferrite 7, the Teflon tube 9, and the ferrite 8 are sequentially formed along the central axis of the permanent magnet. An arrayed ferrite resonator (FIG. 5) is mounted, and the ferrite resonators are arranged like the NRD guide lines 3, 4 and 5 of FIG. 1 at 120 degree intervals, and each of these NRD guide lines 3, 4 and 5 are arranged. The mode compressors 10, 11 and 12 are inserted between the ferrite resonator and the ferrite resonator.

The second embodiment of the present invention is constructed by inserting the stepped mode compressors 13, 14, and 15, wherein the width of the mode compressor of the first embodiment is narrower than the width of the NRD line.

1 is a perspective view of a circulator in which a mode compressor is inserted to minimize transmission loss of a circulator as a first embodiment.

2 is a perspective view of a circulator having a general structure.

3: Schematic diagram of the basic principle of the circulator using the NRD guide.

4: Schematic diagram of a mode existing in the circulator using the NRD guide.

5 is a perspective view of a ferrite resonator inserted in the center of the circulator.

6: Perspective view of an NRD guide track and a disassembled mode sprayer.

7 is a graph showing transmission loss results for the case where the mode compressor is inserted into and not inserted into the three terminals of the circulator.

8 is a perspective view of a circulator for NRD guides in which a wide band characteristic can be obtained by narrowing the width of the mode compressor portion in the circulator in which the mode compressor is inserted as the second embodiment and forming the step shape.

9 is a graph showing a measured value of impedance varying with frequency without narrowing the width of the mode compressor to form a stepped shape.

10 is a graph showing a measurement value of impedance varying with frequency by making a stepped shape by narrowing the width of the mode compressor.

Fig. 11 is a graph showing the transmission loss in the case where the width of the mode compressor is changed to stepped form and the case in which it does not change with respect to Example 2;

(Explanation of symbols for the main parts of the drawing)

1: upper conductor plate

2: lower conductor plate

3: NRD guide line of input port.

4: NRD guide line of isolated port.

5: NRD guide line of output port.

6: permanent magnet.

7, 8: ferrite (ferromagnetic).

9: Teflon tube.

10: Mode sprayer of input port.

11: Mode sprayer of blocking port.

12: Mode sprayer of output port.

13: Mode spreader narrower than NRD guide line of input port.

14: Mode spreader narrower than NRD guide line of blocking port.

15: Mode spreader narrower than NRD guide line of output port.

16: NRD guide line.

17: thin teflon track

18: metal (copper) thin film.

INPUT①: Input port.

OUTPUT②: Output port.

Isolated③: Blocking port.

Example 1

Fig. 1 shows a mode sprayer 10, 11, 12 between an NRD guide line 3, 4, 5 and a ferrite resonator composed of ferrites 7, 8 and Teflon tube 9 as a first embodiment of the present invention. Is a perspective view inserted.

As the NRD guide line used in the present invention uses a PTFE having a dielectric constant of 2.04 and is performed in a 50 GHz band, the height of the line, that is, the interval between the upper and lower conductor plates 1 and 2 is 2.7 mm, and the width of the line is Was 2.4 mm. In addition, ferrite has a dielectric constant of 15 from TDK Co., Ltd. and is 1800G. The ferrite (7,8) having a tangent loss of 0.0008 is ultrasonically processed to make a circular shape, and the thickness is used by grinding. The diameter is 3.37 mm.

First, the general structure of the NRD guide circulator and its principle will be described in detail with reference to FIGS. 2, 3, 4, and 5.

2 is a structure of a generally known circulator for NRD guides. The permanent magnet 6 is inserted into the upper and lower conductor plates 1 and 2 at the center of the upper and lower conductor plates 1 and 2. Then, the ferrite 7, the Teflon tube 9, and the ferrite 8 are sequentially arranged on the central axis of the permanent magnet to form a ferrite resonator. 5 is a perspective view of a ferrite resonator.

Then, NRD guide lines 3, 4, and 5 are arranged at 120-degree intervals around the ferrite resonator to make three ports. In the present invention, as shown in Figures 3 and 4 will be described by selecting the role of each port.

The unnecessary mode, such as the LSE mode, occurs in the bent portion of the NRD guide line or in an asymmetrical or discontinuous region, thereby affecting the circuit characteristics. Therefore, the unnecessary mode occurs in an irreversible device such as an asymmetrical circulator.

Looking at the cause of such an unnecessary mode in the prior art, port ① (3) is the input, port ② (5) is the output, port ③ (4) has a structure of the blocked port 3 In the case of the NRD guide circulator as shown in FIG. 4, when it is assumed that only the LSM mode is input to the input port, the magnetic field distribution of the main transmission wave LSM mode exists only in the axial cross section. Therefore, when the circulator operates, attention is paid to the electromagnetic field distribution of the resonator. The magnetic field is present in the axial cross section for port ② and output as LSM mode. It does not exist in the axial cross section, but forms a loop in the transverse cross section. Thus, it can be seen that there is no LSM mode on this port. On the other hand, since the magnetic field distribution of the LSE mode draws a loop in the cross section in the transverse direction, the port 3 is in a state where the LSE mode tends to exist.

Therefore, the LSM mode input as shown in FIG. 3 is not output to port ③ but is output to port ②. However, at the same time, LSE mode is generated at port 3 to prevent insertion loss. Cause. Therefore, insertion loss can be reduced by suppressing this unnecessary mode.

In order to suppress the unnecessary mode generated when the circulator using the permanent magnet as described above, in the present invention, as shown in Fig. 6, the mode sprayers 10, 11, 12 are connected to the NRD guide lines 3, 4, 5) and the ferrite resonator.

The LSM mode is not affected by the insertion of the metal strip 18 since the center plane of the NRD guide is the electrical wall. However, since the electric field of LSE mode is parallel to the center plane, insertion of a metal strip can be removed within the frequency band by increasing the cutoff frequency. However, since TEM modes can be generated for the LSE mode, the metal strip 18 is configured in the form of a choke of λ / 4 to suppress all unnecessary modes.

The mod spreader is 0.4mm wide at the narrow end and 2.4mm wide at the wide end. The wavelength of the TEM transmission wave is equal to the plane wave wavelength in the dielectric because the electromagnetic field is concentrated in the NRD guide line. Therefore, the length of each choke section is 0.95 mm, which is a quarter of the plane wave wavelength 3.8 mm in the track.

The transmission characteristics of FIGS. 1 and 2 were measured and shown in FIG. 7. The circulator using the permanent magnet of FIG. 2 has an average transmission loss of about 4 dB in the 50 GHz band, and the circulator using the permanent magnet of the first embodiment of FIG. 1 obtains an average transmission loss of 1 dB or less in the 50 GHz band. Could.

(Example 2)

8 is a perspective view of a second embodiment of the present invention. In the first embodiment, the widths of the mode compressors 10, 11 and 12 between the NRD guide lines 3, 4 and 5 and the ferrite resonators are narrowed to form a step.

Here, the thickness of the ferrite (7,8) was 0.342mm based on the experimental basis, the bias magnetic field, that is, the strength of the permanent magnet is 1320Oe was used.

As can be seen in FIG. 9, at the center frequency of 50 GHz, the impedance is located almost at the center of the Smith chart, and thus, it can be said that the state is completely matched. Also, as shown in FIG. 10, even when the modulators 13, 14, and 15 having a narrow width of the half-wavelength of the center frequency are mounted on the circulator using the permanent magnet, characteristics of the center frequency are not significantly affected. .

However, the reactance component changes as the center frequency changes. The narrower mode compressors 13, 14, and 15 also have a reactance component that changes with the change of the center frequency, but satisfy the matching condition over a wide frequency band, thereby enabling wideband.

The size of the mode spreaders 13, 14, and 15 with the optimum width designed based on the above description was about 1.9 mm smaller than the 2.4 mm width of the NRD guide line. And the length of the mode compressor was comprised by 5.8 mm so that it may become the odd multiple of 50-GHz half-wavelength.

9 and 10 show that the bias magnetic field, that is, the strength of the permanent magnet is 1320Oe, the diameter of the ferrites 7 and 8 is 3.37 mm, the thickness is 0.342 mm, and the height of the Teflon tube 9 is 2.016 mm and the diameter is shown. 3.37 mm and internal diameter were 3 mm. However, the results of FIG. 9 show that the widths of the mode compressors 10, 11 and 12 are the same as the NRD guide lines, and FIG. 10 shows the widths of the mode compressors 13, 14 and 15 smaller than the NRD guide lines. This is a graph showing the impedance trajectory according to the center frequency for the case of about 1.9mm.

11 shows results of insertion loss and breaking characteristics of the first and second embodiments of the present invention. When the mode compressor was the same width as the line, it was measured that the bandwidth having the blocking property of 20 dB or less was about 1 GHz. However, as in the second embodiment, the circulator using the permanent magnet mounted with the width of the mode sprayer narrower than the width of the NRD guide line results in a blocking area of 20 dB or less while maintaining the low loss of the first embodiment. Indicates.

Therefore, a circulator using a general permanent magnet as shown in FIG. 2 has a loss of about 4dB due to asymmetry. However, the low loss of the NRD guide was maintained by suppressing the unnecessary mode generated due to the asymmetry of the circulator using the permanent magnet by inserting the mode compressor as in the first embodiment, and the mode of the first embodiment as in the second embodiment. It can be seen that the wideband characteristics can be obtained by inserting a compressor to narrow the width of the mode compressor while maintaining the low loss of the NRD guide.

Many various embodiments of the invention may be constructed without departing from the technical scope of the invention. It is to be understood that the invention is not limited to the specific embodiments described herein. On the contrary, the invention includes various modifications and equivalent constructions that fall within the technical scope of the claimed invention. The appended claims are to be accorded the broadest interpretation so as to encompass all such modifications, equivalent structures, and functions.

As described above, the circulator using the permanent magnet of the present invention can remove the heat generation phenomenon of the electromagnet generated by using the existing electromagnet, eliminate the consumption of electricity, and do not use the power supply circuit added when using the electromagnet In addition, the circulator using the permanent magnet of the present invention reduces the insertion loss of radio waves by inserting a mode sprayer between the NRD guide line and the ferrite resonator of each terminal, thereby achieving desired output characteristics.

Further, by using the width of the mode compressor of the present invention narrower than the width of the NRD guide line, the band of usable frequencies can be widened.

Through the present invention, since the circulator using permanent magnets has excellent characteristics of low loss and wide bandwidth, it can be sufficiently used as an irreversible device such as a modulator and an amplifier.

Claims (3)

Mounting the permanent magnets 6 on the upper and lower conductor plates 1 and 2 and arranging the ferrite 7, the Teflon tube 9 and the ferrite 8 sequentially along the central axis of the permanent magnet; Construct a ferrite resonator, and arrange the NRD guide lines at 120 degree intervals in the ferrite resonator; A circulator using permanent magnets for low loss NRD guides, characterized by inserting mode compressors 10, 11, and 12 between the respective NRD guide lines and the ferrite resonators. Mounting the permanent magnets 6 on the upper and lower conductor plates 1 and 2 and arranging the ferrite 7, the Teflon tube 9 and the ferrite 8 sequentially along the central axis of the permanent magnet; Construct a ferrite resonator, and arrange the NRD guide lines at 120 degree intervals in the ferrite resonator; Circulator using permanent magnet for low loss and wideband NRD guide, characterized by inserting stepped mode presser (13, 14, 15) narrower than NRD line width delete