JP3978502B1 - Strip line type left-handed line - Google Patents

Strip line type left-handed line Download PDF

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JP3978502B1
JP3978502B1 JP2006220026A JP2006220026A JP3978502B1 JP 3978502 B1 JP3978502 B1 JP 3978502B1 JP 2006220026 A JP2006220026 A JP 2006220026A JP 2006220026 A JP2006220026 A JP 2006220026A JP 3978502 B1 JP3978502 B1 JP 3978502B1
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line
intermediate layer
handed
left
unit cell
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JP2008028964A (en
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篤志 真田
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国立大学法人山口大学
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Abstract

PROBLEM TO BE SOLVED: To realize a left-handed line having a strip line structure that does not emit even in a region to be a radiation region and can perform signal transmission without radiation.
An intermediate layer 1 has a strip line structure in which both surfaces of the intermediate layer 1 are surrounded by ground conductors 2 and 3. The intermediate layer conductor 4 disposed in the intermediate layer dielectric 1 forms a unit cell by leaving a dielectric around the metal pattern on the surface of the dielectric substrate, and is constituted by an assembly of the unit cells. The line functions in the left-handed region, and this line has a strip line type transmission mode in which the electric field is concentrated on the metal pattern 4 in the intermediate layer as a basic mode.
[Selection] Figure 3

Description

  The present invention relates to a left-handed line having a strip line structure made of a metamaterial.

Artificially constructs a medium waiting for unnatural properties by arranging small pieces of metal, dielectrics, magnetic materials, superconductors, etc., at sufficiently short intervals (less than 1/10 of the wavelength). can do. This medium is called metamaterials in the sense that it exceeds the natural medium. The properties of metamaterials vary depending on the shape, material, and arrangement of unit particles. Among them, metamaterials whose equivalent permittivity ε and permeability μ are negative at the same time are the electric and magnetic fields. It was named “Left-Handed Materials” because the wave vector is left-handed. On the other hand, a normal medium in which the equivalent permittivity ε and permeability μ are simultaneously positive is called “Right-Handed Materials”. As shown in FIG. 1, the relational areas of the dielectric constant ε, the magnetic permeability μ, and the medium can be classified into the first quadrant to the fourth quadrant according to the positive / negative of the dielectric constant ε and the positive / negative of the magnetic permeability μ.

  In particular, the “left-handed medium (LHM)” is called a backward wave, where there is a wave in which the signs of the wave group velocity (energy propagation velocity) and phase velocity (phase advance velocity) are reversed, Further, it has unique properties such as amplification of an evanescent wave that is an exponentially decaying wave in a non-propagating region. And it is well-known that the line which transmits the backward wave by a left-handed system medium can be artificially comprised (for example, refer nonpatent literatures 1 and 2).

  Based on the concept of the left-handed medium configuration, a line for propagating backward waves by periodically arranging unit cells made of metal patterns has been proposed. So far, its transmission characteristics have been treated theoretically, and it has become theoretically clear that this line has a left-handed transmission band. Conventionally, in a microstrip line configuration as shown in FIG. 2, a left-handed line is produced, and the left-handed transmission characteristics of this microstrip line have been experimentally verified (for example, see Non-Patent Document 2).

  FIG. 2A shows a partial configuration of a left-handed line structure of a microstrip line. The line forms a unit cell by leaving a dielectric around the metal pattern 4 on the surface of the dielectric substrate 1, and the entire surface is formed on the back surface (one surface) of the dielectric substrate constituted by the assembly of the unit cells. And having a ground conductor 3.

In the microstrip line type left-handed line having such a structure, most of the electric field and magnetic field are transmitted inside the dielectric 1, but since the half space of the line is open, a part of the ground conductor is used. Not radiated on the surface. That is, a part of the transmission energy is radiated to the outside and a loss occurs in the transmission line.
DR Smith, WJ Padilla, DC Vier, SC Nemat-Nasser, and S. Schultz, "Composite medium with simultaneously negativepermeability and permittivity," Phys. Rev. Lett., Vol.84, no. 18, pp.4184-4187, May 2000. C. Caloz, and T. Itoh, "Application of the transmission line theory of left-handed (LH) materials to the realization of a microstrip LH line", IEEE-APS Int'l Symp. Digest, vol. 2, pp. 412 -415, June 2002.

  A conventional microstrip line type right / left-handed line has a structure as shown in FIG. 2A and a transmission mode as shown in FIG. 2B, and a so-called open type in which a half space on one side of the line is open. Therefore, in the microstrip line type left-handed line having such a structure, most of the electric field and magnetic field are transmitted inside the dielectric 1, but the half space of the line is open, Is emitted to a surface without a ground conductor. That is, a part of the transmission energy is radiated to the outside, causing a loss in the transmission line, which is inefficient. Therefore, the present invention is a strip line that can transmit a signal without radiation in an open line in which the phase constant of the propagating wave is smaller than the wave number in a vacuum, without radiating even in a so-called radiation area. The purpose is to provide a type left-handed track.

To achieve the above object, stripline type left-handed transmission line according to claim 1 of the present invention, an intermediate layer conductor disposed in the dielectric of the intermediate layer, leaving the dielectric around a metal pattern The unit cell is formed as an assembly, and both sides of the intermediate layer are surrounded by a ground conductor to function in the left-handed region.

Stripline type left-handed transmission line according to claim 2 of the present invention, an intermediate layer conductor disposed in the dielectric of the intermediate layer is a collection of unit cells formed by leaving a dielectric around the metal pattern In which both sides of the intermediate layer are surrounded by a ground conductor, and the value obtained by normalizing the phase constant β of the propagation wave by (π / period a of the unit cell ) is in the range of −1.0 to 0. The configuration.

  As a result, the strip line type left-handed line of the present invention surrounds both the front and back surfaces of the substrate with grounding conductors, so even in an open line where the phase constant of the propagation wave is smaller than the wave number in vacuum, so-called radiation It is possible to transmit signals without radiating without radiating even in the region to be a region, and efficiently transmitting transmission energy without losing the transmission line.

  In the stripline type left-handed line according to claim 3 of the present invention, the unit cell has a unit cell structure that does not use vias, and both surfaces of the intermediate layer are surrounded by a ground conductor.

  As a result, the left-handed line of the strip line structure according to the present invention uses a unit structure that has already been proposed by the present inventor and does not use a via as the unit cell, thereby reducing the production process and reducing the cost. be able to.

  As described above, since the strip line type left-handed line of the present invention surrounds both the front and back surfaces of the substrate with the ground conductor, the open wave line in which the phase constant of the propagating wave is smaller than the wave number in vacuum is so-called. In addition, it does not radiate even in a region that becomes a radiation region, signal transmission can be performed without radiation, and transmission energy can be efficiently transmitted without loss in the transmission line. In addition, by using a unit cell structure that has been proposed by the present inventor and does not use vias as the unit cell, the number of manufacturing steps can be reduced and the cost can be reduced.

  The stripline type left-handed line of the present invention has a stripline structure in which both surfaces of an intermediate layer 1 having an intermediate layer conductor 4 are surrounded by ground conductors 2 and 3 as shown in FIG. As shown in FIGS. 4A and 4B, a more specific configuration of the strip line structure is that an intermediate layer conductor 4 disposed in an intermediate layer dielectric 1 is formed of a metal on the surface of a dielectric substrate. A unit cell is formed by leaving a dielectric around the pattern, and the pattern is constituted by an assembly of the unit cells. FIG. 5 shows an enlarged metal pattern of the intermediate layer conductor of the unit cell.

  The metal pattern of the intermediate layer conductor of the unit cell shown in FIG. 5 extends in the lateral direction in the middle of the metal strip A that serves as an electrode for providing a series gap capacity with adjacent cells, the metal strip B that connects them. If one end of the metal strip C is grounded even if it is not connected to the ground conductor by a via by providing a capacitance with the ground conductor connected to the end of the metal strip C and the metal strip C for providing the parallel inductance. It is comprised from the metal strip D which plays the role of the virtual ground which obtains an equivalent effect.

  FIG. 6A shows an equivalent circuit of a unit cell, and FIG. 6B shows a simplified equivalent circuit. This line has a strip line type transmission mode in which the electric field concentrates on the metal pattern 4 of the intermediate layer as a basic mode. The electromagnetic field in the transmission mode of the strip line formed in this way is as shown in FIG. 3B, and since the front and back surfaces of the line are surrounded by the ground conductors 2 and 3 as they are, radiation is essentially generated. Absent.

  Next, the reason why the strip line in which the front and back surfaces of the line are surrounded by the ground conductors 2 and 3 becomes the strip line type left-handed line of the present invention will be described.

  In a line composed of a strip line type left-handed line and a strip line type right-handed line, the band gap is eliminated by designing the dispersibility (relationship between the phase constant β and the angular frequency ω) well, and in a narrow frequency range. β can be changed rapidly from a negative (left-handed) to a positive (right-handed) value. (Note that the wave number of a wave is often referred to as a “phase constant” for a wave propagating in a certain direction, such as a propagating wave on a transmission line. .)

This will be explained theoretically. Based on the simplified equivalent circuit of the unit cell shown in FIG. 6B, assuming that the phase constant is β and the period of the unit cell is a, the dispersion relation of this periodic structure line is calculated as follows:
β = 1 / a · cos −1 [1 + Z (ω) Y (ω)] (1)
It becomes.

here,
Z (ω) = 1/2 [1 / jωC L
+ JωL R ]
Y (ω) = 1 / [jωL L + 1 / jωC g
] + JωC R
It is.

  The frequency f (= ω / 2π) with respect to the phase constant β is expressed in FIG. 7 as the three-dimensional finite dispersion characteristics of the periodic structure line obtained by applying periodic boundary conditions to the unit cell of the structure of the present invention. When plotted as an electromagnetic field simulation calculation result by the element method, it has a gentle slope and intersects the vertical axis. Here, the horizontal axis indicates a value obtained by normalizing the phase constant β of the propagation wave by (π / a), and the vertical axis indicates the frequency.

  Here, in the dispersion characteristic of FIG. 7, the specifications of the unit cell shown in FIG. 5 are the following examples.

p w = 1.5mm, p h = 2.4mm, c w = 0.5mm, c l = 6.0mm, l l1 = 2.8mm, l w1 = 1.0mm, l l2 = 1.8mm, l w2 = 0.5 mm, unit cell period a = 4.0 mm, thickness s = 1.016 mm, ε γ = 2.17

On the other hand, the wave number k o in vacuum represents the speed of light c o
Then,
k o = ± ω / c o (2)
And is proportional to ω. When this is plotted in the dispersion relation of FIG. 7, it becomes a straight line (Air line) in the figure.

  In FIG. 7, in the frequency range of 9.5 GHz to 10.2 GHz where −1 ≦ β <0, the phase velocity (= ω / β) is negative and the group velocity (= ∂ω / ∂) represented by the slope of the dispersion curve. β) is positive and these signs are reversed, indicating the presence of a backward wave. That is, this is evidence that this medium is a medium exhibiting left-handed characteristics. In the frequency range from 10.2 GHz to 11.8 GHz where 0 <β ≦ + 1, both the phase velocity (= ω / β> 0) and the group velocity (= ∂ω / ∂β> 0) are positive and have the same sign. And shows right-handed characteristics. In the figure, the left-handed and right-handed transmission frequency bands are connected at 10.2 GHz, and it can be seen that there is no band gap between them.

  As described above, the strip line type left-handed line of the present invention is a set of unit cells in which the intermediate layer conductor 4 arranged in the dielectric of the intermediate layer 1 is formed leaving the dielectric around the metal pattern. The intermediate layer 4 has a structure in which both surfaces of the intermediate layer 4 are surrounded by ground conductors 2 and 3, and the value obtained by normalizing the phase constant β of the propagation wave with (π / a) is in the range of −1.0 to 0. It can be realized by making it function.

  As described above, since the strip line type left-handed line of the present invention surrounds both the front and back surfaces of the substrate with ground conductors, even in an open line where the phase constant β of the propagation wave is smaller than the wave number in vacuum, In a so-called radiation region, radiation is not performed, signal transmission can be performed without radiation, and transmission energy can be efficiently transmitted without loss in the transmission line. In addition, by using a unit cell structure that does not use vias, which the inventor has already proposed as a unit cell in a patent application (Japanese Patent Application No. 2005-58443), the manufacturing process can be reduced and the cost can be reduced. it can.

  The strip line type left-handed line of the present invention can be applied not only to a microwave antenna but also to a transmission line, a coupler, a resonator, a distributor, and the like.

FIG. 6 is a relationship area diagram of a dielectric constant ε, a magnetic permeability μ, and a medium. The conventional microstrip line figure. The stripline figure used for this invention. FIG. 3 is a structural diagram of a strip line used in the present invention. Metal pattern of the intermediate layer of the unit cell of the track. The equivalent circuit diagram of the unit cell of a track | line. Numerical simulation calculation example of dispersion characteristics.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Middle layer 2 Upper surface ground conductor 3 Lower surface ground conductor 4 Middle layer conductor (metal pattern)

Claims (3)

  1. The intermediate layer conductor arranged in the dielectric of the intermediate layer is composed of a unit cell formed by leaving a dielectric around the metal pattern , and both sides of the intermediate layer are surrounded by a ground conductor. A strip line type left-handed line characterized by functioning in the left-handed area.
  2. The intermediate layer conductor arranged in the dielectric of the intermediate layer is composed of a unit cell formed by leaving a dielectric around the metal pattern , and both sides of the intermediate layer are surrounded by a ground conductor. A strip line type left-handed system line, wherein a value obtained by normalizing a phase constant β of a propagation wave with (π / unit cell period a) is in a range of −1.0 to 0.
  3. The left-handed line of the stripline structure according to claim 1 or 2, wherein the unit cell has a unit cell structure that does not use a via.
JP2006220026A 2006-06-22 2006-08-11 Strip line type left-handed line Active JP3978502B1 (en)

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JP2006220026A JP3978502B1 (en) 2006-06-22 2006-08-11 Strip line type left-handed line

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5120896B2 (en) * 2006-07-14 2013-01-16 国立大学法人山口大学 Stripline type right / left-handed composite line or left-handed line and antenna using them
CN106450606A (en) * 2016-12-21 2017-02-22 广西科技大学鹿山学院 Ultra-wideband limiting filter based on left-handed material

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103000980B (en) * 2011-09-16 2015-06-03 深圳光启高等理工研究院 Resonant cavity

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5120896B2 (en) * 2006-07-14 2013-01-16 国立大学法人山口大学 Stripline type right / left-handed composite line or left-handed line and antenna using them
CN106450606A (en) * 2016-12-21 2017-02-22 广西科技大学鹿山学院 Ultra-wideband limiting filter based on left-handed material

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