JP2008098703A - Reflection type band-pass filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-performance reflection type band-pass filter for a UWB which has a simple circuit constitution, is easy for use, and can meet standards of an FCC. <P>SOLUTION: Disclosed is the reflection type band-pass filter for super-wideband radio information communication which is provided with two conductors extending in a belt shape on the surface of a dielectric substrate on both sides of a nonconductor portion for securing a predetermined inter-conductor distance across the nonconductor portion. The reflection type band-pass filter is characterized in that conductor widths and the inter-conductor distance are unevenly distributed all over a length direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reflective band-pass filter for ultra wide band (UWB) wireless information communication (hereinafter referred to as UWB). By using this UWB reflective bandpass filter, it is possible to satisfy the spectrum mask defined by the US Federal Communications Commission (FCC).

As the prior art according to the present invention, for example, techniques disclosed in Patent Documents 1 to 9 are known.
US Pat. No. 2,411,555 JP-A-56-64501 JP-A-9-172318 Japanese Patent Laid-Open No. 9-232820 Japanese Patent Laid-Open No. 10-65402 JP-A-10-242746 JP 2000-4108 A JP 2000-101301 A JP 2002-43810 A Y. konishi, "Microwave integrated circuits," pp. 19-21, Marcel Dekker, 1991

However, the band-pass filter proposed in the above-described prior art may not satisfy the FCC regulations due to manufacturing errors.
In addition, among the conventional filters, a configuration in which one microstrip line is provided on the substrate requires a ground conductor under the dielectric, and thus has a structure like a planar dipole antenna, for example. With an antenna, there is a problem that it is difficult to configure a circuit together with the antenna and it is difficult to use.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a high-performance UWB reflective band-pass filter that has a simple circuit configuration, is easy to use, and can meet FCC standards.

  In order to achieve the above object, the present invention provides a UWB for a UWB in which two conductors extending in a strip shape are provided on both sides of a surface of a dielectric substrate via non-conductor portions that secure a predetermined inter-conductor distance. Provided is a reflective bandpass filter, wherein one or both of a conductor width and a distance between conductors are unevenly distributed in the longitudinal direction.

  In the reflective bandpass filter of the present invention, it is preferable that the conductor width is constant and the distance between conductors is unevenly distributed.

  In the reflective band-pass filter of the present invention, it is preferable that the distance between the conductors is constant and the conductor width is unevenly distributed.

  In the reflective bandpass filter of the present invention, the difference between the reflectance in the region where the frequency f is f <3.1 GHz and f> 10.6 GHz and the reflectance in the region where 3.7 GHz ≦ f ≦ 10.0 GHz. Is 10 dB or more, and the variation of the group delay is preferably within ± 0.2 ns in the region of 3.7 GHz ≦ f ≦ 10.0 GHz.

  In the reflective band-pass filter of the present invention, the difference between the reflectance in the region where the frequency f is f <3.1 GHz and f> 10.6 GHz and the reflectance in the region of 3.8 GHz ≦ f ≦ 9.9 GHz. The absolute value of is preferably 10 dB or more, and the variation of the group delay is preferably within ± 0.1 ns in the region of 3.8 GHz ≦ f ≦ 9.9 GHz.

  In the reflective band-pass filter of the present invention, the difference between the reflectance in the region where the frequency f is f <3.1 GHz and f> 10.6 GHz and the reflectance in the region of 4.2 GHz ≦ f ≦ 9.6 GHz. The absolute value of is preferably 10 dB or more, and the variation of the group delay is preferably within ± 0.15 ns in the region of 4.2 GHz ≦ f ≦ 9.6 GHz.

  In the reflective band-pass filter of the present invention, the difference between the reflectance in the region where the frequency f is f <3.1 GHz and f> 10.6 GHz and the reflectance in the region of 4.5 GHz ≦ f ≦ 9.2 GHz. Is 10 dB or more, and the variation of the group delay is preferably within ± 0.05 ns in the region of 4.5 GHz ≦ f ≦ 9.2 GHz.

  In the reflective bandpass filter of the present invention, it is preferable that the characteristic impedance Zc of the input-end transmission line is 10Ω ≦ Zc ≦ 200Ω.

  In the reflection type bandpass filter of the present invention, it is preferable that the termination is terminated with a resistor having the same value as the characteristic impedance or a non-reflection termination.

  In the reflective band-pass filter of the present invention, each conductor is preferably made of a metal plate having a thickness equal to or greater than skin depth at f = 1 GHz.

In the reflective bandpass filter of the present invention, the dielectric substrate has a thickness h of 0.1 mm ≦ h ≦ 10 mm, a relative dielectric constant ε _r of 1 ≦ ε _r ≦ 500, a width W of 2 mm ≦ W ≦ 100 mm, and a length. The length L is preferably 2 mm ≦ L ≦ 500 mm.

  In the reflection-type bandpass filter of the present invention, it is preferable that the longitudinal distribution of the center conductor width and the distance between the conductors is set using a design method based on an inverse problem that derives a potential from spectrum data in the Zakharov-Shabat equation.

  In the reflective band-pass filter of the present invention, it is preferable that the longitudinal distribution of the center conductor width and the inter-conductor distance is set using a window function method.

  In the reflective band-pass filter of the present invention, it is preferable that the longitudinal distribution of the center conductor width and the distance between the conductors is set using the Kaiser window function method.

The reflection-type bandpass filter of the present invention applies the window function method and designs a reflection-type bandpass filter composed of non-uniform microstrip lines. Compared with, the band is very wide, and the fluctuation of the group delay in the transmission band can be made very small, so that the UWB filter specified by the FCC can be realized.
In addition, since a ground conductor is unnecessary under the dielectric, for example, in an antenna having a structure such as a planar dipole antenna, it is easy to configure a circuit together with the antenna, and it is easy to use.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a schematic configuration of a reflective bandpass filter of the present invention. In the figure, reference numeral 1 is a reflection type bandpass filter, 2 is a dielectric substrate, 3 and 4 are conductors, and 5 is a non-conductor portion.

In the reflective bandpass filter 1 of the present embodiment, two conductors 3 and 4 extending in a strip shape are formed on the surface of the dielectric substrate 2 on both sides thereof via non-conductor portions 5 that secure a predetermined inter-conductor distance. And a non-uniform symmetric two-conductor coplanar line in which one or both of the conductor width w and the inter-conductor distance s are unevenly distributed in the longitudinal direction. The two conductors of the non-uniformly symmetric two-conductor coplanar line shown in FIG.
Then, they have the same width w (z).

This non-uniform symmetric two-conductor coplanar line can change the characteristic impedance by changing one or both of the conductor width w and the inter-conductor distance s (see Non-Patent Document 1). For example, FIG. 2 shows the dependence of the characteristic impedance between conductors s when w = 1 mm, h = 2 mm, and ε _r = 45, and FIG. 3 shows s = 1 mm, h = 2 mm, and ε _r = 45. , It represents the dependency of the characteristic width on the conductor width w.

In the present invention, the local characteristic impedance obtained by the inverse problem is configured by changing the conductor width w or the inter-conductor distance s, thereby realizing a band-pass filter.
Hereinafter, based on the Example which concerns on this invention, this invention is demonstrated still in detail. Each example described below is merely an example of the present invention, and the present invention is not limited to the description of these examples.

  A Kaiser window was used in which the frequency f was 3.4 GHz ≦ f ≦ 10.3 GHz, the reflectance was 1, the other regions were 0, and A = 30. In addition, the design was performed with a waveguide length of 1 wavelength at 1 GHz and a characteristic impedance of the system of 50Ω. FIG. 4 shows the distribution of local characteristic impedance obtained by the inverse problem.

FIG. 5 shows the inter-conductor distance s when a substrate having a thickness h = 2 mm and a relative dielectric constant ε _r = 45 is used and the width w of two conductors is 1 mm. Tables 1-3 show a list of the dimensions.

FIG. 6 shows the shape of the central conductor in the reflective bandpass filter produced in this example. In the figure, the thinly filled portion represents the conductor, and the darkly filled portion represents the space between the conductors (surface on which the dielectric layer is exposed). The reflection type bandpass filter is terminated with a non-reflection termination or a resistance of R = 50Ω after the end of the reflection bandpass filter (end face having a position of 65.29 mm). Further, the metal film of the conductor part is assumed to be sufficiently thicker than skin depth δs = √2 / (wμ ₀ σ) at f = 1 GHz. Here, w, μ ₀ , and σ represent the angular frequency, the ceramic rate in vacuum, and the electrical conductivity of metal, respectively. For example, when copper is used, the thickness is 2.1 μm or more. This filter is used in a system having a characteristic impedance of 50Ω.

7 and 8 show the amplitude characteristic and group delay characteristic of the device reflected wave (S ₁₁ ), respectively. As shown in the figure, in the band where the frequency f is 3.7 GHz ≦ f ≦ 10.0 GHz, the reflectance is −1 dB or more, and the variation of the group delay is within ± 0.05 ns. In the region of f <3.1 GHz or f> 10.6 GHz, the reflectance is −17 dB or less.

  A Kaiser window was used in which the frequency f was 3.4 GHz ≦ f ≦ 10.3 GHz, the reflectance was 0.9, the other regions were 0, and A = 30. In addition, the design was performed with the waveguide length being 2 wavelengths at 1 GHz and the characteristic impedance of the system being 50Ω. FIG. 9 shows the distribution of local characteristic impedance obtained by the inverse problem.

FIG. 10 shows the inter-conductor distance s when a substrate having a thickness h = 2 mm and a relative dielectric constant ε _r = 90 is used and the width w of two conductors is 1 mm. Tables 4-6 show the dimension list.

  FIG. 11 shows the shape of the central conductor in the reflective bandpass filter produced in this example. In the figure, the thinly filled portion represents the conductor, and the darkly filled portion represents the space between the conductors (surface on which the dielectric layer is exposed). The reflection type bandpass filter is terminated with a non-reflective termination or a resistance of R = 50Ω after the termination (end face of 95.82 mm). The metal film of the conductor portion is assumed to be sufficiently thicker than the skin depth at f = 1 GHz. For example, when copper is used, the thickness is 2.1 μm or more. This filter is used in a system having a characteristic impedance of 50Ω.

12 and 13 show the amplitude characteristic and group delay characteristic of the device reflected wave (S ₁₁ ), respectively. As shown in the figure, in the band of frequency 3.8 GHz ≦ f ≦ 9.9 GHz, the reflectance is −1 dB or more, and the variation of the group delay is within ± 0.1 ns. In the region of f <3.1 GHz or f> 10.6 GHz, the reflectance is −20 dB or less.

  A Kaiser window with a reflectivity of 1 in the region where the frequency f is 3.7 GHz ≦ f ≦ 10.0 GHz, 0 in the other regions, and A = 30 was used. In addition, the design was performed with the waveguide length of 0.3 GHz at 1 GHz and the system characteristic impedance of 50Ω. FIG. 14 shows the distribution of local characteristic impedance obtained by the inverse problem.

FIG. 15 shows a distance s between conductors when a substrate having a thickness h = 1 mm and a relative dielectric constant ε _r = 90 is used and a width w = 2 mm between two conductors. Table 7 shows the dimension list.

  FIG. 16 shows the shape of the central conductor in the reflective bandpass filter produced in this example. In the figure, the thinly filled portion represents the conductor, and the darkly filled portion represents the space between the conductors (surface on which the dielectric layer is exposed). The reflection type bandpass filter is terminated with a non-reflection termination or a resistance of R = 50Ω after the end of the reflection bandpass filter (end face at a position of 18.59 mm). The metal film of the conductor portion is assumed to be sufficiently thicker than the skin depth at f = 1 GHz. For example, when copper is used, the thickness is 2.1 μm or more. This filter is used in a system having a characteristic impedance of 50Ω.

17 and 18 show the amplitude characteristic and group delay characteristic of the device reflected wave (S ₁₁ ), respectively. As shown in the figure, in the band where the frequency f is 4.2 GHz ≦ f ≦ 9.6 GHz, the reflectance is −2 dB or more and the variation of the group delay is within ± 0.15 ns. In the region of f <3.1 GHz or f> 10.6 GHz, the reflectance is −15 dB or less.

  A Kaiser window with a frequency f of 3.7 GHz ≦ f ≦ 10.0 GHz, a reflectance of 0.8, and 0 in other regions and A = 30 was used. The design was performed with the waveguide length set to 0.3 wavelength at 1 GHz and the characteristic impedance of the system set to 100Ω. FIG. 19 shows the distribution of local characteristic impedance obtained by the inverse problem.

FIG. 20 shows the conductor width w when a substrate having a thickness h = 1 mm and a relative dielectric constant ε _r = 40 is used and the inter-conductor distance s = 1 mm. Table 8 shows the dimension list.

  FIG. 21 shows the shape of the central conductor in the reflective bandpass filter produced in this example. In the figure, the thinly filled portion represents the conductor, and the darkly filled portion represents the space between the conductors (surface on which the dielectric layer is exposed). This reflection type bandpass filter is terminated with a non-reflection termination or a resistance of R = 100Ω after the termination (end face of the position of 20.36 mm). The metal film of the conductor portion is assumed to be sufficiently thicker than the skin depth at f = 1 GHz. For example, when copper is used, the thickness is 2.1 μm or more. This filter is used in a system having a characteristic impedance of 100Ω.

22 and 23 show the amplitude characteristic and group delay characteristic of the device reflected wave (S ₁₁ ), respectively. As shown in the figure, in the band where the frequency f is 4.5 GHz ≦ f ≦ 9.2 GHz, the reflectance is −5 dB or more, and the variation of the group delay is within ± 0.05 ns. In the region of f <3.1 GHz or f> 10.6 GHz, the reflectance is −20 dB or less.

It is a perspective view which shows one Embodiment of the reflection type band pass filter of this invention. It is a graph which shows the distance dependence between the characteristic impedances in a coplanar line. It is a graph which shows the center conductor width dependence of the characteristic impedance in a coplanar line. 4 is a graph showing a distribution of characteristic impedance of a reflective bandpass filter produced in Example 1. FIG. 6 is a graph showing a distance distribution between conductors of a symmetric two-conductor coplanar line in the reflective bandpass filter manufactured in Example 1. FIG. 4 is a graph showing the shape of a symmetric two-conductor coplanar line in the reflective bandpass filter produced in Example 1. 6 is a graph showing the amplitude characteristic of a reflected wave in the reflective bandpass filter produced in Example 1. 4 is a graph showing group delay characteristics of reflected waves in the reflective bandpass filter produced in Example 1. FIG. 6 is a graph showing a distribution of characteristic impedance of a reflective bandpass filter produced in Example 2. 6 is a graph showing the inter-conductor distance distribution of a symmetric two-conductor coplanar line in the reflective bandpass filter produced in Example 2. 6 is a graph showing the shape of a symmetric two-conductor coplanar line in a reflective bandpass filter produced in Example 2. 6 is a graph showing the amplitude characteristic of a reflected wave in the reflective bandpass filter produced in Example 2. 6 is a graph showing group delay characteristics of reflected waves in a reflective bandpass filter produced in Example 2. FIG. 6 is a graph showing a distribution of characteristic impedance of a reflective bandpass filter produced in Example 3. 6 is a graph showing a distance distribution between conductors of a symmetric two-conductor coplanar line in a reflective bandpass filter manufactured in Example 3. 12 is a graph showing the shape of a symmetric two-conductor coplanar line in the reflective bandpass filter produced in Example 3. 6 is a graph showing the amplitude characteristics of reflected waves in the reflective bandpass filter produced in Example 3. 10 is a graph showing group delay characteristics of reflected waves in a reflective bandpass filter produced in Example 3. 10 is a graph showing a distribution of characteristic impedance of a reflective bandpass filter produced in Example 4. 10 is a graph showing a distance distribution between conductors of a symmetric two-conductor coplanar line in a reflective bandpass filter manufactured in Example 4. 10 is a graph showing the shape of a symmetric two-conductor coplanar line in the reflective bandpass filter produced in Example 4. 6 is a graph showing amplitude characteristics of reflected waves in a reflective bandpass filter produced in Example 4. FIG. 10 is a graph showing group delay characteristics of reflected waves in a reflective bandpass filter produced in Example 4.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reflective type band pass filter, 2 ... Dielectric substrate, 3, 4 ... Conductor, 5 ... Non-conductor part.

Claims (14)

This is a reflection type bandpass filter for ultra-wideband wireless information communication in which two conductors extending in a strip shape are provided on both sides of a dielectric substrate through non-conductor portions that secure a predetermined distance between conductors. And
One or both of a conductor width and a distance between conductors are non-uniformly distributed in the longitudinal direction.   The reflective band-pass filter according to claim 1, wherein the conductor width is constant and the distance between conductors is unevenly distributed.   The reflective bandpass filter according to claim 1, wherein the distance between the conductors is constant and the conductor width is unevenly distributed.   The absolute value of the difference between the reflectivity in the region where the frequency f is f <3.1 GHz and f> 10.6 GHz and the reflectivity in the region where 3.7 GHz ≦ f ≦ 10.0 GHz is 10 dB or more. The reflection type bandpass filter according to any one of claims 1 to 3, wherein a variation in group delay is within ± 0.2 ns in a region of 0.7 GHz ≤ f ≤ 10.0 GHz.   The absolute value of the difference between the reflectivity in the region where the frequency f is f <3.1 GHz and f> 10.6 GHz and the reflectivity in the region where 3.8 GHz ≦ f ≦ 9.9 GHz is 10 dB or more. The reflection type bandpass filter according to any one of claims 1 to 3, wherein a variation in group delay is within ± 0.1 ns in a region of .8 GHz ≦ f ≦ 9.9 GHz.   The absolute value of the difference between the reflectivity in the region where the frequency f is f <3.1 GHz and f> 10.6 GHz and the reflectivity in the region where 4.2 GHz ≦ f ≦ 9.6 GHz is 10 dB or more. The reflection type bandpass filter according to any one of claims 1 to 3, wherein a variation in group delay is within ± 0.15 ns in a region of .2 GHz ≦ f ≦ 9.6 GHz.   The absolute value of the difference between the reflectance in the region where the frequency f is f <3.1 GHz and f> 10.6 GHz and the reflectance in the region where 4.5 GHz ≦ f ≦ 9.2 GHz is 10 dB or more, and 4 The reflection type bandpass filter according to any one of claims 1 to 3, wherein a variation in group delay is within ± 0.05 ns in a region of 0.5 GHz ≤ f ≤ 9.2 GHz.   The reflection type bandpass filter according to any one of claims 1 to 7, wherein the characteristic impedance Zc of the input-end transmission line is 10Ω≤Zc≤200Ω.   9. The reflection type band pass filter according to claim 8, wherein the reflection type band pass filter is terminated with a resistor having the same value as the characteristic impedance at the end or a non-reflective end.   The reflective band-pass filter according to claim 1, wherein each conductor is made of a metal plate having a thickness equal to or greater than skin depth at f = 1 GHz. The dielectric substrate has a thickness h of 0.1 mm ≦ h ≦ 10 mm, a relative dielectric constant ε _r of 1 ≦ ε _r ≦ 500, a width W of 2 mm ≦ W ≦ 100 mm, and a length L of 2 mm ≦ L ≦ 500 mm. The reflective band-pass filter according to claim 1, wherein   The longitudinal distribution of the center conductor width and the distance between the conductors is set using a design method based on an inverse problem for deriving a potential from spectrum data in the Zakharov-Shabat equation. Reflective band-pass filter as described.   The reflection-type bandpass filter according to any one of claims 1 to 11, wherein a longitudinal distribution of a center conductor width and a distance between conductors is set using a window function method.   The reflection-type bandpass filter according to any one of claims 1 to 11, wherein a longitudinal distribution of a center conductor width and a distance between conductors is set by using a Kaiser window function method.

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