JP3872200B2 - Non-radiative dielectric line coupler - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-radiative dielectric line coupler, for example, a coupler (coupler) that is incorporated in a millimeter wave integrated circuit or the like and couples a non-radiative dielectric line used as a guide for a high-frequency signal.
[0002]
[Prior art]
As shown in FIG. 5, a non-radiative dielectric line (also referred to as an NRD guide) is configured by arranging parallel plate conductors 2 and 3 above and below a dielectric line 1 having a rectangular cross section. Yes. In such a nonradiative dielectric line, when the interval between the parallel plate conductors 2 and 3 is λ / 2 or less, a high-frequency signal having a wavelength greater than λ is blocked and cannot enter the space between the parallel plate conductors 2 and 3. . When the dielectric line 1 is interposed between the parallel plate conductors 2 and 3, a high-frequency signal can be propagated along the dielectric line 1, and the radiated wave from the high-frequency signal is blocked by the parallel plate conductors 2 and 3. Suppressed by effect. Note that λ is approximately equal to the wavelength of a high-frequency signal (electromagnetic wave) propagating in vacuum. In FIG. 5, a part of the upper parallel plate conductor 3 is cut out.
[0003]
By the way, in this non-radiative dielectric line, as a coupler used for dividing and coupling a high-frequency signal (electromagnetic wave), two dielectric lines 5 and 6 are arranged at a predetermined interval L as shown in FIG. Was used. FIG. 6 is a schematic diagram of a dielectric line, and the upper and lower parallel plate conductors are omitted.
[0004]
The electromagnetic wave incident from the port a of the dielectric line 5 is partially transmitted through the dielectric line 5 as it is and output from the port b, and partly electromagnetically coupled to the dielectric line 6 and output from the port c. Is done.
[0005]
Similarly, the electromagnetic wave incident from the port d is divided into the port b and the port c and output. When electromagnetic waves are simultaneously incident on port a and port d, the divided electromagnetic waves are mixed and output to ports b and c.
[0006]
By appropriately adjusting the distance L between the two dielectric lines, it is possible to obtain a transmittance having a desired division ratio. In non-radiative dielectric lines, this coupler is used to form dividers and couplers (for example, IEEE Transactions on Microwave Theory and Techniques, MTT-31, No. 8, August 1983, P648-654). (Kaihei 8-8621, JP-A-6-174824, etc.).
[0007]
In addition, the dielectric lines 5 and 6 do not have to be straight lines, and are usually connected to other non-radiative dielectric line circuits, and therefore, as shown in FIG. A combination of the lines 8 or a combination of two curved dielectric lines (not shown) is used.
[0008]
In an asymmetric coupler in which the linear dielectric line 7 and the curved dielectric line 8 are combined, or two curved dielectric lines having different curvature radii are combined, two linear dielectric lines 5, 6 or two identical curvatures are used. It is known that the transmittance to the port c when entering from the port a is smaller than that using a radius dielectric line. This is considered to be because the high-frequency signals in the two dielectric lines are not symmetrical.
[0009]
[Problems to be solved by the invention]
However, since the conventional non-radiative dielectric line coupler has a narrow bandwidth, it is insufficient for devices that require a wide band such as communication. In addition, since it is a narrow band, it is necessary to finely adjust the interval between the dielectric lines so as to have a desired transmittance at the used frequency, and it is difficult to manufacture.
[0010]
That is, FIG. 8 shows the calculation results of the characteristics of the conventional nonradiative dielectric line coupler of FIG. This characteristic diagram is shown for a case where a high frequency signal incident from port a is equally divided into port b and port c at a use frequency of 60 GHz. S _ba represents the transmittance of the high-frequency signal output to the port b, and S _ca represents the transmittance of the high-frequency signal output to the port c. As shown in FIG. 8, the transmittance varies greatly depending on the frequency, and when the frequency deviates from 60 GHz, the transmittance also varies greatly. For this reason, the bandwidth of the conventional coupler is usually only about 1 GHz. Such a bandwidth of about 1 GHz is insufficient for devices that require a wide band such as communication.
[0011]
In addition, since the transmittance of the coupler greatly varies when the distance L between the two dielectric lines 5 and 6 varies, it is necessary to arrange the two dielectric lines 5 and 6 with high accuracy. This hindered the mass productivity of non-radiative dielectric lines.
[0012]
Further, as described above, in an asymmetric coupler in which a linear dielectric line and a curved dielectric line are combined, or two curved dielectric lines having different curvature radii are combined, a high-frequency signal in the two dielectric lines is used. Because of this asymmetry, there is a problem that a high-frequency signal as designed is not output to the port c. Therefore, conventionally, it has been necessary to configure a coupler by using a curved dielectric line having the same radius of curvature, or by combining a curved dielectric line having a sufficiently large radius of curvature and a linear dielectric line. Therefore, the degree of freedom in design is reduced, and at the same time, miniaturization of the non-radiative dielectric line circuit is hindered.
[0013]
INDUSTRIAL APPLICABILITY The present invention has a wider bandwidth and can be applied to devices that require a wide band such as communication, and at the same time, can be easily mass-produced, has a high degree of design freedom, and is a small non-radiative dielectric. An object is to provide a line coupler.
[0014]
[Means for Solving the Problems]
The non-radiative dielectric line coupler of the present invention has a linear or curved first dielectric line between a pair of parallel plate conductors and a curved shape having a radius of curvature smaller than the radius of curvature of the first dielectric line. provided adjacent the second dielectric waveguide, a high frequency signal transmitted through the port d of the port a and / or the second dielectric waveguide of the first dielectric waveguide is, port b and the first dielectric waveguide In the transmittance curve with respect to the frequency of the high frequency signal output to the port c of the second dielectric line and output from the first and second dielectric lines, the transmittance | Sij | (i Is b or c, j is a or d) has an extreme value.
[0015]
Here, in the first and second dielectric lines, it is desirable that the extreme values of the transmittance at the used frequency coincide.
[0016]
The first and second dielectric lines are preferably made of a dielectric having a relative dielectric constant of 4 or more, and the second dielectric line is preferably curved with a curvature radius of 8 mm or less. Furthermore, it is desirable that the first and second dielectric lines are made of a dielectric material having a relative dielectric constant of less than 4, and the second dielectric line has a curved shape with a radius of curvature of 12 mm or less.
[0017]
[Action]
In the conventional non-radiative dielectric line coupler, two linear dielectric lines, a curved dielectric line having the same radius of curvature, a curved dielectric line having a sufficiently large radius of curvature and a linear dielectric line are used. It was configured by combining. As described above, this is because a high-frequency signal as designed is not output from port a to port c.
[0018]
FIG. 9 shows the characteristics of an asymmetric coupler in which a linear dielectric line and a curved dielectric line are combined. In the asymmetric coupler, the transmittance to the port b is larger and the transmittance to the port c is smaller than that of the coupler using two linear dielectric lines.
[0019]
Therefore, the point at which the transmittance to port b and port c becomes equal shifts to the low frequency side as compared with the coupler (FIG. 8) using two linear dielectric lines.
[0020]
The inventors of the present invention have found that the above-mentioned problems can be solved at once by actively utilizing such problems of the asymmetric coupler, and have reached the present invention. In other words, conventionally, for example, when a coupler in which a high-frequency signal is equally distributed to port b and port c at 60 GHz, as shown in FIG. 8, the curve of S _{ba and} the curve of S _ca at a use frequency of 60 GHz. had to be crossed, in the present invention, as shown in FIG. 10 is the extremes of the curve extremes and S _ca curves S _ba in the use frequency 60GHz is to match.
[0021]
That is, by reducing the radius of curvature of one of the curved dielectric lines, the asymmetry of the two dielectric lines is further increased, and the distance between the two dielectric lines is adjusted, as shown in FIG. Thus, the transmittance at the operating frequency is an extreme value. Therefore, in the non-radiative dielectric line coupler of the present invention, the transmittance to the port b and the port c is an extreme value at the use frequency, so the slope of the transmittance curve near the use frequency becomes very small. The bandwidth is wide, and it can be applied to devices that require a wide band such as communication. FIG. 10 is a graph showing the calculation result of the relationship between the transmittance and frequency of the non-radiative dielectric line coupler of the present invention.
[0022]
In addition, because the bandwidth is wide, the transmittance hardly changes even if the distance between the two dielectric lines that make up the coupler changes slightly. Therefore, adjustment is easy and mass production is easy, and design flexibility is high. Become.
[0023]
Furthermore, the nonradiative dielectric line coupler of the present invention can be downsized because the bandwidth can be widened by making the radius of curvature smaller than that of the conventional dielectric line. The non-radiative dielectric line coupler of the present invention is suitably used when used at a high frequency of 50 GHz or higher.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
A perspective view of the non-radiative dielectric line coupler of the present invention is shown in FIG. In FIG. 1, reference numeral 14 is a pair of parallel plate conductors, 15 is a linear first dielectric line, and 16 is a curved second dielectric line. Reference numerals a and b are input / output ports of the first dielectric line 15 and are hereinafter referred to as ports a and b, respectively. Reference numerals c and d denote input / output ports of the second dielectric line 16 and are hereinafter referred to as a port c and a port d, respectively. In FIG. 1, a part of the upper parallel plate conductor 14 is cut out.
[0025]
In such a non-radiative dielectric line coupler, a high-frequency signal transmitted through the first dielectric line 15 is output in the high-frequency signal transmission direction of the first dielectric line 15 and is output from the second dielectric line 16. Is.
[0026]
The high frequency signal transmitted through the second dielectric line 16 may be output from the first dielectric line 15 while being output in the high frequency signal transmission direction of the second dielectric line 16. Further, the high frequency signals input from the first dielectric line 15 and the second dielectric line 16 are divided and output in the high frequency signal transmission direction of the first dielectric line 15 and the second dielectric line 16. There may be.
[0027]
The parallel plate conductor 14 is an insulating material in which a conductive plate such as Cu, Al, Fe, SUS (stainless steel), Ag, Au, Pt, or the like is formed on the surface in terms of high electrical conductivity and workability. A plate may be used.
[0028]
The dielectric lines 15 and 16 are preferably made of a low loss resin material such as Teflon and a low dielectric constant ceramic material such as cordierite. This is because they are low loss and easy to process, and are suitable for mass production.
[0029]
FIG. 1 shows a non-radiative dielectric line coupler in which a linear first dielectric line 15 and a curved second dielectric line 16 are combined, but of course, it does not depart from the scope of the present invention. For example, the first dielectric line and the second dielectric line may be curved.
[0030]
When a high frequency signal is incident from the port a, the decrease in the transmittance to the port c depends on the curvature radius of the curved second dielectric line 16. For this reason, the minimum value of the transmittance to the port b and the maximum value of the transmittance to the port c increase and decrease as the radius of curvature of the curved second dielectric line 16 decreases, respectively. Further, the position of this extreme value changes depending on the distance between the two dielectric lines 15 and 16. For this reason, the non-radiative dielectric line coupler of the present invention is realized by intentionally using the curved second dielectric line 16 having a smaller radius of curvature than the conventional one. By setting the radius of curvature of the second dielectric line 16 and the distance between the two dielectric lines 15 and 16 to a predetermined value, a non-radiative dielectric line coupler having an extreme value of a desired transmittance at a desired frequency is configured. It can be done.
[0031]
The extreme value and frequency of the transmittance are determined by the curvature radius of the curved second dielectric line 16 and the distance between the two dielectric lines 15 and 16, the width, height and ratio of the dielectric lines 15 and 16 used. Varies with dielectric constant. Therefore, the optimal radius of curvature of the second dielectric line 16 and the distance between the two dielectric lines 15 and 16 are determined experimentally or by calculation with respect to the desired transmittance, the desired frequency, and the dielectric line to be used. There is a need.
[0032]
In the non-radiative dielectric line coupler of the present invention, it is desirable that the first and second dielectric lines are made of a dielectric having a dielectric constant of 4 or more, and the second dielectric line has a curved shape having a curvature radius of 8 mm or less. . In particular, it is desirable that the first dielectric line is linear. Moreover, it is desirable that the first and second dielectric lines have a dielectric constant of 4 to 10 from a practical aspect.
[0033]
When the first and second dielectric lines are made of a dielectric having a dielectric constant smaller than 4, it is desirable that the second dielectric line has a curved shape with a radius of curvature of 12 mm or less. In particular, it is desirable that the first dielectric line is linear. The first and second dielectric lines are preferably dielectrics having a dielectric constant of 2 to 3. The radius of curvature refers to R in FIG. 7, for example.
[0034]
If the above range is satisfied, the greater the difference in the radius of curvature of the two dielectric lines, the smaller the extreme value of the transmittance to the port b. For example, the height is 2.25 mm, the width is 1.0 mm, the dielectric is A 3 dB coupler that uses a dielectric line with a rate of 5 and has the same transmittance to ports b and c at 60 GHz can be realized by using a linear dielectric line and a curved dielectric line with a curvature radius of about 4 mm.
[0035]
In addition, this invention is not limited to said embodiment, A various change does not interfere in the range which does not deviate from the summary of this invention.
[0036]
【Example】
Two parallel plate conductors of Cu 100 × W 100 × Thickness 8 mm made of Cu are prepared, and a height of 2.25 mm × width of cordierite having a relative dielectric constant of 4.8 between these parallel plate conductors. A 1 mm linear first dielectric line and a curved second dielectric line were arranged, and the non-radiative dielectric line coupler of FIG. 1 was produced as follows.
[0037]
In this embodiment, a case in which a coupler that equally distributes a high-frequency signal to ports b and c at 60 GHz is shown.
[0038]
A straight first dielectric line having a length of 80 mm was used, and both ends thereof were connected to a measurement waveguide via a converter. The curved second dielectric line uses a 180 ° bend (semi-circular shape) with a radius of curvature of 3.9 mm, linear dielectric lines are connected to both ends of the second dielectric line, and a measurement conductor is connected via a transducer. Connected to wave tube.
[0039]
The distance between the linear first dielectric line and the curved second dielectric line was experimentally determined to be 1.4 mm so that the transmittance has an extreme value at 60 GHz. For comparison, a symmetric coupler using two 180 ° bends having a radius of curvature of 12.7 mm was also manufactured as a conventional coupler.
[0040]
About the present invention and the conventional nonradiative dielectric line, the millimeter wave (several tens to several hundreds GHz band) transmission characteristics were measured by a network analyzer [8757C] manufactured by Hewlett-Packard Co., and the result of the nonradiative dielectric line coupler of the present invention 2 and 3 show the results of the conventional non-radiative dielectric line coupler in FIG. Since the transmittance on the vertical axis in the figure includes the loss of the converter, the transmittance of only the actual coupler is about 1 dB larger than this value.
[0041]
2 and 3, it can be seen that the non-radiative dielectric line coupler according to the present invention has a wide bandwidth because high frequency signals substantially equal to the ports b and c are distributed over a wide frequency range of about 59 to 61.5 GHz. On the other hand, in the conventional coupler, it is understood that the transmittances of the port b and the port c are equal only in a very narrow frequency range of about 60 to 60.5 GHz.
[0042]
【The invention's effect】
With the non-radiative dielectric line coupler of the present invention, the bandwidth can be very wide, so that the transmittance hardly changes even if the distance between the two dielectric lines is changed slightly, so that a wide band such as communication is required. At the same time it can be applied to equipment, it can be easily mass-produced and the degree of freedom in design is increased.
[0043]
Furthermore, in the non-radiative dielectric line coupler of the present invention, the bandwidth can be widened by making the radius of curvature smaller than that of the conventional dielectric line, so that a reduction in size can be achieved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a non-radiative dielectric line coupler of the present invention.
FIG. 2 is a graph showing the relationship between the transmittance and frequency of the non-radiative dielectric line coupler of FIG. 1;
FIG. 3 is a graph showing a part of FIG. 2 in an enlarged manner.
FIG. 4 is a graph showing the relationship between the transmittance and frequency of a conventional non-radiative dielectric line coupler.
FIG. 5 is a perspective view of a non-radiative dielectric line.
FIG. 6 is a schematic diagram of a conventional non-radiative dielectric line coupler using two linear dielectric lines.
FIG. 7 is a schematic diagram of a conventional non-radiative dielectric line coupler using a linear dielectric line and a curved dielectric line.
8 is a graph showing the calculation result of the relationship between the transmittance and the frequency of the non-radiative dielectric line coupler of FIG. 6;
9 is a graph showing a calculation result of a relationship between transmittance and frequency of the non-radiative dielectric line coupler of FIG.
FIG. 10 is a graph showing the calculation result of the relationship between the transmittance and frequency of the non-radiative dielectric line coupler of the present invention.
[Explanation of symbols]
14 ... Parallel plate conductor 15 ... First dielectric line 16 ... Second dielectric line

Claims (2)

A linear or curved first dielectric line and a curved second dielectric line having a radius of curvature smaller than the radius of curvature of the first dielectric line are provided adjacent to each other between a pair of parallel plate conductors. , the high frequency signal transmitted through the port d of the port a and / or the second dielectric waveguide of the first dielectric waveguide is, the output port c of the port b and the second dielectric waveguide of the first dielectric waveguide In the transmittance curves with respect to the frequency of the high-frequency signal output from the first and second dielectric lines, the transmittance | Sij | (where i is b or c, j is a or d), respectively. Has an extreme value, a non-radiative dielectric line coupler. 2. The non-radiative dielectric line coupler according to claim 1, wherein the first and second dielectric lines have the same extreme value of transmittance at the operating frequency.

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