JP2019153978A - Orbit angular motion amount mode pseudo traveling wave resonator and orbit angular motion amount antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an OAM mode pseudo traveling wave resonator capable of easily switching a mode order while fixing an operating frequency, and an OAM antenna device using the same. SOLUTION: A pseudo traveling wave resonator is provided by branching from a transmission line portion of a microwave, a series branch circuit including a capacitive element equivalently, and an inductive element, respectively, and is equivalent to an inductive element. A plurality of N unit cell circuits having at least one parallel branch circuit included in the above are connected in a ring shape in a longitudinal manner, and the forward propagation constant and the reverse propagation constant are different from each other. Operate the transmission line device in a resonant state. The transmission line portion of each unit cell is magnetized in different directions with respect to the microwave propagation direction and has spontaneous magnetization so as to have gyro anisotropy, or is magnetized by an external magnetic field, and the circuit of the parallel branch is, for example, It is an inductive stub circuit connected so as to be inserted inside a non-reciprocal transmission line device, and operates at a mode order l of OAM mode. [Selection diagram] FIG. 4A

Description

  The present invention relates to an orbital angular momentum (Orbital Angular Momentum) mode pseudo traveling wave resonator and an orbital angular momentum (Orbital Angular Momentum) antenna device using the same.

  Recently, electromagnetic wave propagation using orbital angular momentum (hereinafter referred to as “OAM”) has been developed in the fields of physics, optics, and wireless communication to realize multi-channel transmission by orthogonal multimode that enables high-speed and large-capacity communication systems. It has been studied. In general, the total angular momentum J can be classified into two elements. In terms of electronic properties, the orbital angular momentum (OAM) 1 of the electrons revolving around the nucleus and the spin up / down characteristic that is unique to electrons A distinction is made between spin angular momentum (SAM) s corresponding to two values. This behavior of the electronic system can be associated with the behavior of electromagnetic wave propagation (optical system). In the case of an optical system, the OAM corresponds to an optical vortex in which the trajectory of the light spirals, while the SAM is a left / right circularly polarized wave. Point to.

  1A and 1B are examples of the phase distribution of the electromagnetic field in the lateral plane of the propagating OAM mode (see, for example, Non-Patent Document 1). Here, FIG. 1A shows the OAM mode order l = + 1. FIG. 1B is a photographic image of the phase distribution when the OAM mode order l = + 2. FIG. 2 is an example of an electromagnetic field in the transverse plane of the propagating OAM mode, and is a schematic state diagram when the OAM mode order l = + 2.

  For example, in the conventional OAM mode signal transmission system disclosed in Non-Patent Document 2, it is necessary to design and arrange antennas corresponding to each OAM mode, and the OAM mode signal used according to the number of multiplexed channels is used. The number is determined. Therefore, since the transmission / reception antenna is different for each channel, the number of antennas increases in proportion to the increase in the number of channels. If a plurality of orthogonal OAM modes can be transmitted and received simultaneously, a large-capacity communication system can be realized.

  Various OAM mode generation apparatuses and methods and application apparatuses have been proposed so far, and some conventional examples are shown below.

  Patent Document 1 proposes a lens antenna that realizes an OAM mode, Patent Document 2 proposes a transmission / reception system that multiplexes using radio signals having a plurality of OAM propagation modes, and Patent Document 3 uses OAM. Thus, an antenna device that multiplexes and separates electromagnetic waves has been proposed.

JP 2017-228856 A JP 2017-130791 A Japanese Patent Laying-Open No. 2015-027042

S. M. Mohammadi et al., "Orbital angular momentum in radio -A system study," IEEE Transactions on Antennas Propagation., Vol. 58, No. 2, pp. 565-572, February 2010. Weite Zhang et al., "Multi-OAM-mode microwave communication with the partial arc sampling receiving scheme", IEEE International Microwave Symposium, 2016, pp. 1-3. Q. Bai, et al., "Experimental circular phased array for generating OAM radio beams," Electron Letters, 2014, pp. 1414-1415. L. Marrucci et al. "Spin-to-orbital conversion of the angular momentum of light and its classical and quantum applications," Journal of Optics, Vol. 13, No. 6, pp. 1-13, April 2011. Y. Pan et al., "Generation of orbital angular momentum radio waves based on dielectric resonator antenna," ’IEEE Antennas Wireless Propagation Letters, Vol. 16, pp. 385-388, June 2016.

  For example, in the phased array antenna disclosed in Non-Patent Document 3, when the mode order of the OAM mode is switched, it is necessary to optimally give the initial phase to the feeding line to each antenna with high accuracy. There has been a problem that the phase switching control becomes more complicated with the increase in the number.

  FIG. 3 is a diagram illustrating a configuration method (see, for example, Non-Patent Document 4) for generating an OAM mode according to a conventional example, and is a schematic perspective view illustrating an example of an OAM mode conversion method by transmitting a phase plate. . In the OAM mode generation method of FIG. 3, the mode order is converted by applying a phase plate to the input of the single mode OAM mode. However, in the mode conversion using the conventional phase plate, since the mode order is determined by the phase plate, it is necessary to prepare a phase plate according to the mode number in order to generate a plurality of higher order modes. was there.

  For example, in the configuration method for generating an OAM mode according to the conventional example disclosed in Non-Patent Document 5, an OAM mode generation device using a whispering gallery mode (WGM) of a ring resonator is disclosed. Here, the whispering gallery mode (WGM) is a resonance mode by a standing wave generated in the circumferential direction in the ring resonator, and the resonance frequency is determined by the ring size. By increasing the number of feeder lines to two and appropriately giving the phase difference, the turning direction such as clockwise or counterclockwise can be switched, but the mode order cannot be changed.

  The object of the present invention is to solve the above-mentioned problems, and to have a simple configuration as compared with the prior art, and an OAM mode pseudo traveling wave resonator capable of easily switching the mode order with the operating frequency fixed, and the same Another object is to provide an OAM antenna apparatus using the antenna.

The OAM mode pseudo traveling wave resonator according to the first invention is:
A microwave transmission line portion, a series branch circuit equivalently including a capacitive element, and at least one parallel branch circuit equivalently including an inductive element and branched from the transmission line portion, respectively A non-reciprocal transmission line device configured by connecting a plurality of N unit cell circuits having a cascade configuration in a ring shape and having different propagation constants in the forward direction and in the reverse direction is operated in a resonance state A pseudo traveling wave resonator,
The transmission line part of each unit cell is magnetized in a direction different from the propagation direction of the microwave and has a gyro anisotropy or is magnetized by an external magnetic field,
The parallel branch circuit is
(1) An inductive stub circuit connected to be inserted inside or outside the ring-shaped nonreciprocal transmission line device;
(2) A capacitive stub circuit connected to be inserted outside or inside the ring-shaped nonreciprocal transmission line device, or (3) a circuit combining the inductive stub circuit and the capacitive stub circuit. ,
The ring-shaped nonreciprocal transmission line device has a nonreciprocity of the nonreciprocal transmission line device as Δβ,
The period of the nonreciprocal transmission line device is p,
By satisfying the following expression when l is a predetermined integer,
It operates with a mode order l in the OAM mode.

In the OAM mode pseudo traveling wave resonator,
The parallel branch circuit is
(1) An inductive stub circuit connected so as to be inserted inside the ring-shaped nonreciprocal transmission line device, or (2) connected so as to be inserted outside the ring-shaped nonreciprocal transmission line device. Capacitive stub circuit,
It is.

The OAM antenna apparatus according to the second invention is
The pseudo traveling wave resonator;
The pseudo traveling wave resonator includes a feed line for inputting a microwave.

  Therefore, according to the OAM mode pseudo traveling wave resonator and the OAM antenna apparatus using the same according to the present invention, the mode order is easily switched while having a simple configuration as compared with the prior art and the operating frequency is fixed. be able to.

It is an example of the phase distribution of the electromagnetic field in the transverse plane of the propagating OAM mode, and is a photographic image of the phase distribution when the OAM mode order L = + 1. It is an example of the phase distribution of the electromagnetic field in the transverse plane of the propagating OAM mode, and is a photographic image of the phase distribution when the OAM mode order L = + 2. It is an example of the electromagnetic field in the horizontal direction surface of the propagating OAM mode, and is a schematic state diagram when the OAM mode order L = + 2. It is a figure which shows the structural method which produces | generates the OAM mode which concerns on a prior art example, Comprising: It is a model perspective view which shows the example of the OAM mode conversion method by making a phase plate permeate | transmit. It is a top view which shows the structural example of the OAM antenna apparatus using the pseudo | simulation traveling wave ring resonator comprised from a nonreciprocal metamaterial based on one Embodiment of this invention. It is a longitudinal cross-sectional view about the A-A 'line | wire of FIG. 4A. It is a circuit diagram which shows the equivalent circuit of the unit cell circuit 20P of a reciprocal CRLH line. It is a circuit diagram which shows the equivalent circuit of the unit cell circuit 20 of the nonreciprocal CRLH line | wire used with the OAM antenna apparatus of FIG. 4A. It is a top view which shows the structural example of the OAM antenna apparatus using the pseudo traveling wave ring resonator comprised from a nonreciprocal metamaterial based on the modification of this invention. It is a graph which shows a dispersion | distribution curve in the case of mode order l = ± 1 in the nonreciprocal CRLH transmission line comprised with the ferrite semicircle ring. It is a graph which shows a dispersion | distribution curve in the case of mode order l = +/- 2 in the nonreciprocal CRLH transmission line comprised by the ferrite semicircle ring. 4B is a photographic image showing the phase distribution when the mode order is 1 = ± 1, which is a simulation result of the OAM antenna device of FIG. 4A. FIG. 4B is a photographic image showing the phase distribution when the mode order is 1 = ± 2 in the simulation result of the OAM antenna device of FIG. 4A. 4B is a photographic image of a prototype of the OAM antenna device of FIG. 4A. FIG. 4B is a photographic image showing the phase distribution when the mode order is 1 = ± 1, which is an experimental result of the OAM antenna device of FIG. 4A. FIG. 4B is a photographic image showing the phase distribution when the mode order is 1 = ± 2, which is an experimental result of the OAM antenna device of FIG. 4A.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following embodiments, the same or similar components are denoted by the same reference numerals.

  In an embodiment of the present invention, a new configuration method that radiates an OAM mode and enables mode order switching at the same frequency is used, and is configured using a pseudo traveling wave ring resonator composed of a nonreciprocal metamaterial. An OAM antenna device is proposed below.

  FIG. 4A is a top view showing a configuration example of an OAM antenna device using a pseudo traveling wave ring resonator composed of a nonreciprocal metamaterial according to an embodiment of the present invention, and FIG. 4B is a top view of FIG. It is a longitudinal cross-sectional view about A 'line.

  4A and 4B, the ring resonator is composed of a nonreciprocal right / left-handed composite (CRLH) transmission line, and a ferrite ring 16 having a width w, an outer diameter R, and a thickness of 0.8 mm is provided in the axial direction. And is placed directly on the ground conductor 11 as part of the dielectric substrate 10. In the same plane as the ferrite ring 16 on the ground conductor 11, the dielectric substrate 10 having the same thickness as the ferrite ring 16 is placed inside and outside the ferrite ring 16. A strip conductor 12 for a transmission line 31 is formed on the upper surface of the ferrite ring 16, and a transmission line 31 that is a ring-shaped microstrip line is formed together with the ground conductor 11 on the lower surface. Further, a negative effective dielectric constant and a negative magnetic permeability are realized by periodically inserting a capacitor Cp in the serial branch and an inductive stub circuit 32 in the parallel branch with a period p, respectively, with respect to the transmission line 31. ing. In a ring structure consisting of non-reciprocal CRLH lines, the inductive stub circuit 32 is connected to the strip conductor 12 in order to enhance the structure asymmetry using a combination of the curvature of the transmission line 31 and the asymmetric insertion of the inductive stub circuit 32. An inductive short-circuit stub circuit configured to include a connected strip conductor 13 and a via conductor 14 connected to the strip conductor 13 and grounded to the ground conductor 11, and inside the ring-shaped transmission line 31. Inserted. As a result, the nonreciprocity is enhanced by the curvature of the transmission line 31, and the ring resonator is reduced in size.

Although not implemented in the structures of FIGS. 4A and 4B, as another means for enhancing nonreciprocity, a capacitive stub circuit 33 is provided outside the ring-shaped transmission line 31 as shown in FIG. It may be inserted, or may be constituted by a combination of an inductive stub circuit 32 and a capacitive stub circuit 33. In the case of the pseudo traveling wave resonator shown in FIGS. 4A and 4B, the feed line 35 for inputting the microwave signal via the port P11 includes the strip conductor 15 formed on the dielectric substrate 10 having the ground conductor 11 on the back surface. The feed line 35 is connected to a ring resonator via a capacitor Cp, and the pseudo traveling wave resonator operates in parallel resonance. Incidentally, as shown in FIG. 4B, with the ferrite ring 16, in place of the ferrite ring 16 may be provided with electromagnets 50 for generating an external magnetic field H ₀ in an axial direction (or the magnetic field generator such as a magnet).

  5A is a circuit diagram showing an equivalent circuit of the unit cell circuit 20P of the reciprocal CRLH line, and FIG. 5B is a circuit diagram showing an equivalent circuit of the unit cell circuit 20 of the non-reciprocal CRLH line used in the OAM antenna apparatus of FIG. 4A. .

Without applying an external magnetic field H ₀ to the ferrite ring 16 in FIGS. 4A and 4B, the equivalent circuit of the unit cell circuits 20P when no magnetization is as shown in Figure 5A. 5A, a unit cell circuit 20P is a transmission circuit having a period p between a port P1 composed of terminals T1 and T2 and a port P12 composed of terminals T3 and T4.
(1) and the capacitance _{C L,} the impedance Zse the serial branch comprising a series circuit of an inductance _{L R,}
(2) and the capacitance _{C R,} constituted by a parallel branch admittance Ysh comprising a series circuit of an inductance _{L L.}

Here, the series resonance frequency and the parallel resonance frequency of the unit cell circuit 20P are determined by the impedance Zse of the series branch and the admittance Ysh of the parallel branch, respectively. Inserted inductance L _L in parallel with the inserted capacitance C _L in series are respectively realized negative magnetic permeability and negative permittivity.

  FIG. 5B shows an equivalent circuit of the unit cell circuit 20 of the nonreciprocal CRLH transmission line. Unlike the unit cell circuit 20P of the reciprocal CRLH circuit of FIG. 5A, a transmission line whose phase constant changes according to the propagation direction of the electromagnetic wave is shown. thinking. In the nonreciprocal CRLH line constituting the pseudo traveling wave resonator according to the present embodiment, the occurrence of nonreciprocity is caused by asymmetric insertion of the admittance Y of the inductive stub circuit 32 in the parallel branch. Non-reciprocity can be manifested not only in the inductive stub circuit 32 realizing a negative dielectric constant but also in the asymmetric insertion of the capacitive stub circuit 33 (FIG. 6).

  In order for the pseudo traveling wave ring resonator using this nonreciprocal metamaterial to satisfy the resonance condition, the phase difference when an electromagnetic wave such as a microwave goes around the ring-shaped transmission line 31 is 2πl (l = ± 1, ± 2). , ...). Since the phase gradient in the nonreciprocal CRLH transmission line depends on the nonreciprocal phase shift characteristic Δβ, the condition of the following equation may be satisfied.

However, Δβ is the nonreciprocity of the CRLH line constituting the resonator, and is the difference between the phase constants β ₊ and β _{− in} the clockwise direction and the counterclockwise direction (β ₊ −β ₋ ) / 2. Using an equivalent circuit model, Δβ = (β _p −β _m ) / 2. p is the length of the unit cell of the CRLH line (hereinafter referred to as the period), N is the number of unit cell circuits 20 of the CRLH line included in the ring resonator, l is an arbitrary integer, and actually the order of the OAM mode Corresponding to

In the case of the ring structure of FIGS. 4A and 4B, the number of cells is N = 20. At this time, in order to satisfy l = ± 1, it is only necessary that the nonreciprocal CRLH line constituting the resonator satisfies the relationship of Δβp / π = ± 0.1. In order to obtain l = ± 2, Δβp / It is only necessary to satisfy the relationship of π = ± 0.2. In the non-reciprocal CRLH line, the non-reciprocity Δβ can be changed to a desired value by appropriately selecting the externally applied DC magnetic field H ₀ , so that the same frequency can be obtained without changing the dimensions of the structure. The phase gradient in the line can be switched while being fixed.

Therefore, when the values of the period p and the number of cells N are given as the structural parameters of the ring resonator, the nonreciprocity Δβ can be changed to a desired value by appropriately switching the externally applied DC magnetic field H _0. For various integer values l that satisfy the equation, the resonance condition equation is satisfied. As a result, various OAM mode radiations corresponding to the mode order l can be realized. The greater the number that the mode order l can take, the more OAM mode orders that can be handled. In order to increase the size of the mode order l, as can be seen from the resonance conditional expression, the number of cells N is increased to increase the antenna size, or when the antenna size is fixed, the nonreciprocity Δβ is increased. There is a need to. Therefore, in the case of the pseudo traveling wave resonator according to the present embodiment, the ring size of the transmission line 31 and the nonreciprocity of the transmission line 31 determine the maximum value of the OAM mode order that can be handled.

  FIG. 6 is a top view showing a configuration example of an OAM antenna device using a pseudo traveling wave ring resonator composed of a nonreciprocal metamaterial according to a modification of the present invention.

The order of the OAM mode is switched by changing the effective magnetization in the numerical simulation described later and changing the externally applied DC magnetic field H ₀ in the experiment described later. However, the OAM mode positive and negative switching insertion direction of the switching of the inductive stubs or by changing the direction of the supply current of the electromagnet 50 (or by changing the orientation of the permanent magnet), the direction of the externally applied DC magnetic field H ₀ This can be done by switching. In the structure of the present embodiment, it is inserted inside the ring-shaped transmission line 31 so that the nonreciprocity is enhanced by a combination of the line curvature and the asymmetric insertion of the inductive stub circuit 32. However, even when the capacitive stub circuit 33 is inserted outside the ring-shaped transmission line 31, the OAM mode can be generated.

  Furthermore, even when two or more stub circuits 32 and 33 are inserted, if the nonreciprocity satisfies the resonance condition so that the phase difference in one round of the line is 2πl, the inductive stub circuit 32 and the capacitance There is no particular limitation on the combination of insertion of the sex stub circuit 33. In addition, the nonreciprocity is reduced, but regarding the insertion of the stub, it is possible to operate the OAM mode radiation even if the inductive stub is inserted outside the ring or the capacitive stub is inserted inside. It is. At this time, it is necessary to increase the mode order by increasing the ring size of the transmission line 31.

  In the above embodiment, the inductive stub circuit is inserted inside the ring made of the nonreciprocal CRLH line, but may be inserted outside. Moreover, although the capacitive stub circuit is inserted on the outer side of the ring composed of the nonreciprocal CRLH line, it may be inserted on the inner side.

In order to confirm that the OAM mode is radiated from the nonreciprocal CRLH ring resonator, the transmission characteristics of the nonreciprocal line constituting the resonator and the vicinity of the resonator are obtained by a commercially available electromagnetic field simulator HFSS (version 16) based on the finite element method. The electromagnetic field distribution of was numerically calculated. The structural parameters used in the electromagnetic field simulation are as follows.
(1) The outer diameter R of the ferrite ring 16 = 13 mm,
(2) Transmission line 31 has a line width w = 4 mm, a period p = 3.56 mm,
(3) The thickness of the ferrite ring 16 and the thickness t of the dielectric substrate 10 are 0.85 mm,
(4) Series capacitor Cp = 0.6 pF,
(5) Length ls = 0.45 mm and width ws = 1.5 mm of the parallel branch inductive stub circuit 32
(6) Input capacitor Cin = 0.6 pF.

  Before examining the resonator characteristics, in order to investigate the transmission characteristics of the non-reciprocal CRLH line having curvature, the S parameter of the non-reciprocal CRLH transmission line composed of a ferrite semicircular ring was obtained by numerical calculation and measurement.

  FIG. 7A is a graph showing a dispersion curve when the mode order is 1 = ± 1 in a nonreciprocal CRLH transmission line composed of ferrite semicircular rings. FIG. 7B is a graph showing a dispersion curve when the mode order l = ± 2 in a nonreciprocal CRLH transmission line composed of a ferrite semicircular ring. Note that the structural parameters have the same values as in the case of the later ring resonator. In FIG. 7A and FIG. 7B, a dotted line shows a numerical simulation value, and a continuous line shows the measured value of an experimental result.

First, in the numerical simulation, the effective magnetization μ _{0 Mef} corresponding to the four cases of mode order 1 = ± 1, ± 2 was examined. As described above, the resonance operation condition is that the phase constants of the forward propagation and the reverse propagation of the nonreciprocal CRLH line constituting the pseudo traveling wave resonator of N = 20 cells coincide, that is, two When the phase constant at the frequency at which the dispersion curve intersects has a mode order l = ± 1, the normalized phase constant Δβp / π = ± 0.1 is satisfied, and when the mode order l = ± 2, the normalized phase constant Δβp / π = ± 0.2 may be satisfied. As a result of numerical calculation,
(1) For mode order l = + 1, effective magnetization μ ₀ M _ef = + 90 mT,
(2) For mode order l = −1, effective magnetization μ ₀ M _ef = −90 mT,
(3) In the case of mode order l = + 2, effective magnetization μ ₀ M _ef = + 178 mT,
(4) In the case of mode order l = −2, effective magnetization μ ₀ M _ef = −178 mT
Met.

Similarly, in the case of the experiment, the externally applied DC magnetic field μ0Hex corresponding to the four cases of mode order 1 = ± 1, ± 2 was examined. As a result, in FIGS. 7A and 7B,
(1) When the mode order is l = + 1, the externally applied DC magnetic field μ0Hex = + 87 mT,
(2) When the mode order is l = −1, the externally applied DC magnetic field μ0Hex = −74 mT,
(3) When the mode order is l = + 2, the externally applied DC magnetic field μ0Hex = + 181 mT,
(4) In the case of mode order l = −2, externally applied DC magnetic field μ0Hex = −171 mT
Met.

When attention is paid to the non-reciprocity Δβ of the dispersion curve in FIGS. 7A and 7B, it can be seen that in FIG. 7A, the value of Δβp / π is about 0.1 at the intersection of the two dispersion curves as the operating point. Similarly, in FIG. 7B, it can be seen that the magnitude of nonreciprocity Δβ is approximately 0.2. As described above, in order to set the phase difference in one round of the ring-shaped transmission line 31 to 2πl,
(1) When the mode order l = ± 1, the relationship Δβp / π = ± 0.1 is satisfied,
(2) In the case of mode order l = ± 2, the relationship of Δβp / π = ± 0.2 may be satisfied.
Therefore, switching of the OAM mode can be realized by switching the magnetic field direction of the externally applied DC magnetic field N0 without changing the structure.

  FIG. 8 shows a simulation result of the OAM antenna apparatus of FIG. 4A and is a photographic image showing the phase distribution when the mode order l = ± 1. FIG. 9 is a photographic image showing the phase distribution when the mode order is 1 = ± 2, which is a simulation result of the OAM antenna apparatus of FIG. 4A. 8 and 9 show numerical calculation examples of the phase distribution of the near electromagnetic field of the designed pseudo traveling wave resonator.

8 and FIG. 9 is a plane where the phase distribution is measured, and a plane with z = 50 mm is selected as a position away from the resonator by the free space wavelength λ ₀ , and the phase distribution is extracted. The size of the observation region is 200 mm × 200 mm parallel to the xy plane, and corresponds to a size of approximately 4λ ₀ × 4λ ₀ . In the pseudo traveling wave resonator, the effective magnetization effective magnetization μ ₀ M _ef corresponding to the mode orders l = ± 1, ± 2 of the four OAM modes is set to the same value as that of the transmission line 31 described above, and radiated Investigating electromagnetic field distribution. In OAM mode
(1) For mode order l = + 1, the effective magnetization μ ₀ M _ef = + 90 mT,
(2) When the mode order is l = −1, the effective magnetization μ ₀ M _ef = −90 mT,
(3) In the case of mode order l = + 2, the effective magnetization μ ₀ M _ef = + 178 mT,
(4) When the mode order is l = −2, the effective magnetization μ ₀ M _ef = −178 mT,
The near electromagnetic field distribution at resonance was investigated.

FIG. 8 shows the phase distribution of the electromagnetic field when the mode order l = ± 1 and FIG. 9 shows the mode order l = + 2. The operating frequencies were 6.05 GHz and 7.05 GHz, respectively. In this design, non-reciprocal CRLH ring resonator, with a change in externally applied DC magnetic field H _0, characteristic of the CRLH line constituting the resonator changes significantly, the operating frequency is the intersection of the dispersion curve varies This is due to the failure. This variation in operating frequency can be greatly reduced by increasing the ring size of the antenna device and reducing the nonreciprocity of the transmission line 31.

  From the results of FIGS. 8 and 9, it was confirmed by numerical simulation that the electromagnetic waves radiated from the pseudo traveling wave ring resonator correspond to the OAM modes of mode orders l = ± 1 and l = ± 2.

  In order to experimentally confirm that the mode can be switched by changing the OAM mode radiation and the applied DC magnetic field, the inventors of the present invention prototyped the designed pseudo traveling wave ring resonator, Distribution measurements were made.

  FIG. 10 is a photographic image of a prototype of the OAM antenna device of FIG. 4A. FIG. 11 is a photographic image showing the phase distribution when the mode order is 1 = ± 1, which is the experimental result of the OAM antenna apparatus of FIG. 4A. Further, FIG. 12 is a photographic image showing the phase distribution when the mode order is l = ± 2 as the experimental result of the OAM antenna apparatus of FIG. 4A.

  The structural parameters of the prototype of the OAM antenna device (hereinafter referred to as the prototype antenna device) are the same as those used in the numerical simulation. The ferrite ring 16 included in the prototype antenna device is composed of two semicircular ring-shaped ferrite materials made of YIG polycrystal, and the dielectric substrate 10 is composed of a fluororesin multilayer substrate. The near electromagnetic field distribution of the ring resonator was measured by receiving it with an electrically small loop antenna.

  As is apparent from FIGS. 11 and 12, OAM mode radiation having mode orders l = ± 1 and l = ± 2 is obtained as in the numerical simulation results of FIGS. The operating frequencies are 6.05 GHz and 7.05 GHz, respectively. From the above, it was confirmed that the mode order of OAM radiation generated from the pseudo traveling wave ring resonator can be switched by appropriately selecting the externally applied DC magnetic field.

  As described above in detail, according to the present invention, it is possible to provide an OAM antenna apparatus that has a simple configuration compared to the prior art and can easily switch the mode order while fixing the operating frequency.

10 ... dielectric substrate,
11, 12, 13, 15 ... strip conductors,
14 ... via conductor,
16: Ferrite ring,
20: Unit cell circuit,
31 ... transmission line,
32, 33 ... stub circuit,
35 ... Feed line,
50 ... Electromagnet,
Cp, Cin ... capacitor
P1, P2, P11 ... ports.

Claims (3)

A microwave transmission line portion, a series branch circuit equivalently including a capacitive element, and at least one parallel branch circuit equivalently including an inductive element and branched from the transmission line portion, respectively A non-reciprocal transmission line device configured by connecting a plurality of N unit cell circuits having a cascade configuration in a ring shape and having different propagation constants in the forward direction and in the reverse direction is operated in a resonance state A pseudo traveling wave resonator,
The transmission line part of each unit cell is magnetized in a direction different from the propagation direction of the microwave and has a gyro anisotropy or is magnetized by an external magnetic field,
The parallel branch circuit is
(1) An inductive stub circuit connected to be inserted inside or outside the ring-shaped nonreciprocal transmission line device;
(2) A capacitive stub circuit connected to be inserted outside or inside the ring-shaped nonreciprocal transmission line device, or (3) a circuit combining the inductive stub circuit and the capacitive stub circuit. ,
The ring-shaped nonreciprocal transmission line device has a nonreciprocity of the nonreciprocal transmission line device as Δβ,
The period of the nonreciprocal transmission line device is p,
By satisfying the following expression when l is a predetermined integer,
An orbital angular momentum mode pseudo traveling wave resonator, characterized by operating in an orbital angular momentum mode mode order l. The parallel branch circuit is
(1) An inductive stub circuit connected so as to be inserted inside the ring-shaped nonreciprocal transmission line device, or (2) connected so as to be inserted outside the ring-shaped nonreciprocal transmission line device. Capacitive stub circuit,
The orbital angular momentum mode pseudo traveling wave resonator according to claim 1. The pseudo traveling wave resonator according to claim 1 or 2,
An orbital angular momentum antenna apparatus comprising a feed line for inputting a microwave to the pseudo traveling wave resonator.