JP6379072B2 - Beam scanner - Google Patents

Description

  The present invention relates to a technique for facilitating manufacture of a beam scanner.

  Conventionally, a leaky wave beam scanner has to use a wide frequency band in order to increase the scanning angle by changing the frequency. In recent years, leaky wave antennas have been reported that have realized a declination to both the backfire and the endfire from the concept of a composite right / left hand system due to the development of left-handed metamaterials through a transmission path approach. Further, beam scanners using metamaterials include leaky wave beam scanners (non-patent document 1) using electrical sweeping using a varactor diode by a transmission path approach, and waveguide-type leaky wave beam scanners using frequency sweeping. (Non-Patent Document 2).

  FIG. 9 shows a leaky wave waveguide beam scanner using frequency sweeping. Examples of such a beam scanner include a method of creating a waveguide and a periodic short stub by metal cutting, or a method of producing by electroforming after forming a waveguide and a short stub. In addition, as a method of periodically producing the iris, there is a method in which a separately prepared iris layer is alternately arranged with a stub. In addition, there are a method of creating periodic irises by metal cutting, a method of creating periodic iris molds by electroforming, etc., both of which depend on the positional relationship and size of short stubs and irises. High dimensional accuracy is required. In particular, since the slot is in the order of sub-millimeters in the millimeter wave or terahertz wave band, the waveguide is of the same size, and in the case of a stub, the groove depth is shallow and the pitch interval is narrowed. In order to manufacture such a leaky wave waveguide antenna, high dimensional accuracy of the order of several tens of μm is required.

Sungjoon Lim, Christophe Caloz, and Tatsuo Itoh, “Metamaterial-Based Electronically Controlled Transmission-Line Structure as a Novel Leaky-Wave Antenna With Tunable Radiation Angle and Beamwidth”, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 53, NO. 1 , JANUARY 2005 Takaoki Ikeda, Kunio Sakakibara, Toru Matsui, Nobuyoshi Kikuma, and Hiroshi Hirayama, “Beam-Scanning Performance of Leaky-Wave Slot-Array Antenna on Variable Stub-Loaded Left-Handed Waveguide”, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 56 , NO. 12, DECEMBER 2008

  However, in order to construct a periodic stub or iris of the beam scanner, a manufacturing technique that requires a high degree of positional accuracy is required, so that it is difficult to manufacture and cannot be manufactured at low cost.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a beam scanner that can be easily manufactured.

  In order to solve the above problems, the beam scanner of the present invention is a beam scanner in which a dielectric substrate having a hole for forming a waveguide is laminated, and in the first portion in the circumferential direction of the waveguide, The one or more dielectric substrates through which a plurality of vias penetrate and the one or more dielectric substrates through which no via penetrates are alternately laminated, and the second portion other than the first portion is laminated. A plurality of vias pass through the dielectric substrate, and a conductive layer is formed on each dielectric substrate through which the via passes.

  According to the present invention, since the dielectric substrate that does not penetrate the via functions as a slot and can be manufactured using the dielectric substrate lamination technique, the beam scanner can be easily manufactured.

It is a perspective view of the beam scanner concerning this Embodiment. It is a perspective view which shows the cross section in the A line of FIG. It is sectional drawing in the A line of FIG. It is the figure which looked at the direction of the code | symbol M of FIG. It is the figure seen in the direction of the code | symbol N of FIG. It is the figure which looked at the direction of the code | symbol N of FIG. 3 about the beam scanner of a modification. It is a figure which shows an example of the frequency dependence about the distribution of the antenna gain (Directivity (dBi)) in a beam scanner. It is a figure which shows the antenna gain (Directivity (dBi)) with respect to the period p of the slot / leakage wave waveguide layer, the number of slots of the dielectric substrate 1 in one slot / leakage wave waveguide layer, and the antenna deflection angle (Direction). It is a figure which shows the leaky wave waveguide type beam scanner by the conventional frequency sweep.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a beam scanner according to the present embodiment. FIG. 2 is a perspective view showing a cross section taken along line A of FIG. 3 is a cross-sectional view taken along line A in FIG.

  The beam scanner is obtained by laminating dielectric substrates 1, and the waveguide 2 penetrates in the laminating direction. The opening shape of the waveguide 2 is rectangular, and a waveguide connection port 21 for connecting a waveguide (not shown) to the waveguide 2 is attached to the foremost dielectric substrate 1.

  The material of the dielectric substrate 1 may be a ceramic mixed material mixed with ceramics or glass filler, or a polymer material such as polyimide, but a material having a small dielectric loss is desirable.

  The total number of dielectric substrates 1 is, for example, about 10 to 40 layers. By increasing this, the waveguide 2 can be lengthened.

  The height H of the waveguide 2 is, for example, 250 μm, and the width W is, for example, 500 μm. The longitudinal length of the waveguide connection port 21 is 864 μm, for example, and the lateral width is 432 μm, for example.

  The beam scanner is formed by laminating a dielectric substrate 1 on which a conductor layer 3 indicated by a thick line is formed in the z direction. The thickness of the dielectric substrate 1 is, for example, several tens to several hundreds μm. A hole having the same size as the opening shape of the waveguide 2 is formed in the dielectric substrate 1 in advance, and the waveguide 2 having a constant opening area and shape is formed by stacking.

  The beam scanner is divided into a first portion 1A in the direction around the central axis of the waveguide 2 (circumferential direction) and a remaining second portion 1B.

(First part 1A)
The first portion 1A contacts, for example, one of the two long sides of the waveguide 2 and the external space of the beam scanner. For example, the first portion 1A is provided from one end of the waveguide 2 to the other end.

  In the first portion 1A, one or more dielectric substrates 1 through which the plurality of vias 4 penetrate and one or more dielectric substrates 1 through which the vias 4 do not penetrate are alternately stacked. One or more portions of the dielectric substrate 1 through which the vias 4 do not penetrate are referred to as leakage wave waveguide layers (reference numeral 1a).

  The vias 4 are filled with metal, and are, for example, cylindrical, and a plurality of vias are arranged at a predetermined interval. The via 4 may be a quadrangular prism or the like, and the intervals are not necessarily the same. The same applies to the via 4 below.

  A part of the electromagnetic wave introduced into the waveguide 2 passes through the leaky wave waveguide layer 1a and is emitted to the outside. That is, this part functions as a slot.

  Increasing the total number of dielectric substrates 1 increases the number of slots and increases the antenna gain.

  On the other hand, a part of the electromagnetic wave introduced into the waveguide 2 enters the portion of the dielectric substrate 1 through which the via 4 penetrates, but is reflected by the via 4 and the conductor layer 3 and returns to the waveguide 2.

  In order to suppress leakage of electromagnetic waves from between the vias 4, the interval between the vias 4 is desirably ¼ or less of a wavelength determined from a frequency in a desired band.

  In the figure, the one-layer dielectric substrate 1 through which the via 4 penetrates and the leaky wave waveguide layer 1a are alternately laminated. The number of dielectric substrates 1 through which the vias 4 penetrate may be two or more. For example, the leftmost dielectric substrate 1 in FIG. 3 has two layers and the rightmost layer has two layers, and the number of layers may be partially changed in this way. The number of dielectric substrates 1 in the leaky wave waveguide layer 1a may be one layer or three or more layers.

  In the first portion 1A, the conductor layer 3 (thick line) is formed on the entire surface of each dielectric substrate 1 through which the via 4 passes, except for the position of the via 4. The conductor layer 3 (thick line) is also formed over the entire surface of the dielectric substrate 1 of the leaky wave waveguide layer 1a facing the back surface (surface without the conductor layer 3). On the other hand, the conductor layer 3 is not formed between the dielectric substrates 1 of the leaky wave waveguide layer 1a.

  The thickness of the conductor layer 3 is, for example, several to several tens of μm, and is formed by silk screen printing or plating. The material of the conductor layer 3 may be gold, silver, tungsten, or copper. The conductor layer 3 covers not only the inner wall of the waveguide 2 with the same potential by covering the front and back surfaces of the dielectric substrate 1 from the via 4 to the waveguide 2, but also has a corrugated structure with a wavelength equal to or less than the wavelength. Can be formed.

  The shorter the leakage wave waveguide layer 1a (total thickness of the dielectric substrate 1) is, the less affected by dielectric loss, it is preferable to make it as short as possible. For example, the total thickness is 1000 μm (1 mm).

(Second part 1B)
The second portion 1B is in contact with the remaining long side and two short sides of the waveguide 2 and the external space of the beam scanner. For example, the second portion 1B is provided from one end of the waveguide 2 to the other end.

  In the second portion 1B, a plurality of vias 4 penetrate through the laminated dielectric substrate 1, and the conductor layer 3 is formed over the entire surface of one of the dielectric substrates 1.

  A part of the electromagnetic wave introduced into the waveguide 2 enters the dielectric substrate 1 of the second portion 1B, but is reflected by the via 4 and the conductor layer 3 and returns to the waveguide 2.

  Therefore, the interval between the vias 4 is desirably ¼ or less of the wavelength determined from the frequency of the desired band.

  The portion of the dielectric substrate 1 from the via 4 closest to the waveguide 2 to the waveguide 2 functions as a stub (reference numeral 2A in FIG. 4 to be described later) and an iris (reference numeral 2B in FIG. 4 to be described later). Inductive impedance is generated. Therefore, since it is an important factor for designing antenna characteristics, it is necessary to set a desired distance with respect to a desired band and deflection angle.

  For example, in general, for impedance matching in a power feeding section using a metal waveguide and a dielectric laminated substrate, the distance from the center of the via 4 closest to the waveguide 2 to the inner wall of the waveguide 2 corresponds to a predetermined center frequency. Set to 1/2 of the wavelength to be used. This distance is considered to correspond equivalently to the groove depth of the corrugated structure.

  Actually, the effective reflection point of the electromagnetic wave also depends on the interval between the vias 4 and the diameter of the vias 4, and the distance is calculated by numerical calculation.

For example, when the dielectric constant of the dielectric substrate 1 is 6.8, the thickness is 100 μm, the diameter of the via 4 is 100 μm, and the center frequency is 300 GHz, the effective dielectric constant of the dielectric substrate 1 is ε _eff = ( 1 + ε _r ) / 2, and the wavelength in the dielectric substrate 1 is λ _eff = λ / ε _eff ^0.5. _Therefore , the distance from the center of the via 4 to the inner wall of the waveguide 2 in the stub is λ _eff / It is slightly larger than 2 and about 250 μm.

  The shortest distance from the center of the via 4 closest to the waveguide 2 to the inner wall of the waveguide 2 is determined in consideration of the mechanical characteristics (strength) of the dielectric substrate 1 and is suitable for manufacturing. In order to construct a leaky wave antenna that realizes the deflection angle to both the backfire and the endfire, the effective phase constant is reversed between positive and negative (composite right / left-handed configuration) in the desired frequency band. The distance from the center of the via 4 in the stub to the inner wall of the waveguide 2 is set.

  4 is a view of the direction of the symbol M in FIG. 3, and FIG. 5 is a view of the view in the direction of the symbol N in FIG. In FIG. 4, the stub is indicated by reference numeral 2A, and the iris is indicated by reference numeral 2B.

  In FIG. 4, the dielectric substrate 1 of the first portion 1A is not visible and the conductor layer 3 is visible, whereas in FIG. 5, the portion of the dielectric substrate 1 of the first portion 1A is visible. Yes. The shorter the length L from the waveguide 2 to the external space in the first portion 1A, the smaller the influence of dielectric loss, which is preferable. The length L is, for example, 1000 μm (1 mm).

(Modification)
FIG. 5 is a view of the modified beam scanner as viewed in the direction of reference numeral N in FIG.

  In the first portion 1 </ b> A, the air holes 5 are formed in the dielectric substrate 1 (leakage wave waveguide layer / slot) through which the vias 4 do not penetrate, and the material of the dielectric substrate 1 does not exist in the air holes 5. Thereby, the dielectric loss by the material of the dielectric substrate 1 can be reduced more.

  The beam scanner according to the present embodiment can solve the problem, that is, the problem that the dielectric loss of the material of the dielectric substrate 1 increases at high frequencies, the propagation loss increases, and the antenna efficiency decreases.

  For this purpose, for example, as described above, the height H of the waveguide 2 is 250 μm and the width W is 500 μm. For example, the stub is 110 μm and the iris is 100 μm. The stub and iris are parameters that are adjusted as appropriate so as to obtain a desired electromagnetic wave radiation pattern and band characteristics, and are not necessarily constant in all layers of the dielectric substrate 1.

  The effect of the beam scanner according to the present embodiment will be described using a chart. As described above, the height H of the waveguide 2 is 250 μm, the width W is 500 μm, the stub is 110 μm, the iris is 100 μm, and the total number of the dielectric substrates 1 is 30 layers.

  FIG. 7 is a diagram showing the frequency dependence of the distribution of antenna gain (Directivity (dBi)) in such a beam scanner. This distribution is a result obtained by calculation. As shown in the figure, it can be seen that a deflection characteristic of ± 30 degrees or more is obtained at 250 GHz to 340 GHz.

  FIG. 8 is a diagram showing the period p of the slot / leakage wave waveguide layer, the number of layers of the dielectric substrate 1 in one slot / leakage wave waveguide layer, and the antenna gain (Directivity) with respect to the antenna deflection angle (Direction). is there. As shown in the figure, a high antenna gain can be obtained at any period p and any antenna deflection angle by designing a large number of slots of the dielectric substrate 1 in one slot / leakage wave waveguide layer. it can.

  The beam scanner according to the present embodiment can basically be manufactured by a dielectric substrate lamination technique, and component parts such as a waveguide 2, a stub, an iris, and a slot can be easily manufactured collectively. Therefore, the beam scanner can be manufactured at low cost.

  In addition, by forming the waveguide 2 with holes formed in advance in the dielectric substrate 1, the dielectric loss of the material of the dielectric substrate 1 at high frequencies can be reduced, and the antenna gain can be improved.

  Further, in the portion of the dielectric substrate 1 through which the via 4 penetrates, the distance between the center of the via 4 closest to the waveguide 2 and the inner wall of the waveguide 2 is set to a predetermined distance, so that an external connection connected to the beam scanner is performed. Impedance matching with the metal waveguide can be performed, and a desired pass band can be set as the center band.

  Further, by periodically providing the leaky wave waveguide layer 1a, a periodic slot can be formed, and the gain characteristic of the beam scanner can be widened.

DESCRIPTION OF SYMBOLS 1 Dielectric substrate 2 Waveguide 3 Conductor layer 4 Via 1A 1st part 1B (for a beam scanner) 2nd part 1a (for a beam scanner) Leaky wave waveguide layer (slot)

Claims (2)

A beam scanner in which a dielectric substrate having a hole for forming a waveguide is laminated,
In the first portion in the circumferential direction of the waveguide, one or more dielectric substrates through which a plurality of vias and one or more dielectric substrates through which a via does not penetrate are alternately laminated,
In the second part other than the first part, a plurality of vias penetrates the laminated dielectric substrate,
A conductor layer is formed on each dielectric substrate through which the via penetrates. The beam scanner according to claim 1, wherein an air hole is formed in each dielectric substrate through which the via does not penetrate.