FR2619658A1 - SLOTTED ANTENNA - Google Patents

Abstract

The present invention relates to a slot type antenna. The antenna is characterized in that it comprises a rectangular waveguide W surrounded by metal plates 1, 3, 4, 7, 8 to form a rectangular waveguide space, a horn waveguide 5 connected to the rectangular waveguide W to communicate therein a horn waveguide space. The present invention finds application in particular in the field of signal broadcasting.

Description

The present invention relates to a slot antenna having a waveguide

rectangular for the

  communication, dissemination and others.

  Referring to Fig. 44 showing a conventional slot antenna having a circular waveguide, the electromagnetic wave is propagated in the TEM coaxial waveguide which is represented by cylindrical coordinates as shown in Fig. 45. the wave propagates coaxially around a central feed opening, slits of

  radiation are arranged coaxially or spirally.

  Such a circular antenna is suitable for the circularly polarized wave. However, there are problems when used to radiate linear polarization, since the side lobe becomes large and the antenna gain is reduced in comparison to the circularly polarized wave. An object of the present invention is to provide a slotted antenna having a rectangular waveguide

  which can emit not only the circulating polarized wave

  but also high efficiency linear polarization. Another object of the present invention is to provide an antenna which can compensate for a difference

  phase of an electric field in a waveguide.

  In accordance with the present invention, a slotted antenna is provided comprising a rectangular waveguide surrounded by metal plates to form a rectangular waveguide space, a horn waveguide connected to the rectangular waveguide for communicating a horn waveguide space with the rectangular waveguide space, and having a power supply input aperture at one end thereof, the rectangular waveguide having a certain number of wave radiation slots on

one of the metal plates.

  By adjusting the disposition of the slots, the linear polarization and the circularly polarized wave

  both can be emitted from slots.

  According to one aspect of the invention, the rectangular waveguide has a terminal resistance to an end plate thereof and includes means for matching an end plate thereof to increase the energy. of the radiated wave from the slits adjacent to the

extreme plate.

  In another aspect, a metal plate opposite to the metal plate having the slots comprises a slow wave or delay means such as a metal plate striated, wrinkled or ribbed to retard

the propagated wave.

  In addition, the present invention provides a slotted antenna comprising a rectangular waveguide surrounded by

  of metal plates to form a guide-space

  rectangular waveguide, a horn waveguide connected to the rectangular waveguide for communicating a horn waveguide space therein to the rectangular waveguide space, and having an aperture of power supply input at one end thereof, the rectangular waveguide having a number of wave radiation slots on one of the plates

  metallic, a parabolic reflector provided between the

  cornet waveguide pace and the rectangular waveguide space for reflecting the wave to the rectangular waveguide so that a plane compensated in phase or

  equiphase plane of the wave can be flattened.

  The invention will be better understood, and other purposes, features, details and advantages thereof

  will become clearer during the description

  explanatory text which will follow with reference to the accompanying schematic drawings given solely by way of example illustrating several embodiments of the invention and in which:

  FIG. 1 is a perspective view representing

  a slot antenna according to a first embodiment of the invention; - Figure 2 is a perspective sectional view of the slot antenna along a line A-A 'of Figure 1; FIG. 3 is a diagram explaining wave propagation modes in the slot antenna represented in orthogonal coordinates; FIG. 4 is a diagram explaining wave propagation phases in a horn waveguide of the slotted antenna; Fig. 5 is a graph showing an energy density characteristic at a longitudinal section of a rectangular waveguide; FIG. 6 is a diagram representing a

  electric field distribution to a cross-section

  dirty of a rectangular waveguide of the slotted antenna; Fig. 7a is a perspective view of a horn waveguide made in a second embodiment of the present invention; FIG. 7b is a perspective view of a modification of the horn waveguide; FIG. 8 is a perspective view of another modification of the horn waveguide; FIG. 9 is a plan view of the slot antenna of the second embodiment; FIG. 10 is a perspective sectional view of a slot antenna according to a third embodiment of the present invention; FIG. 11 is a curve showing an energy density characteristic at a longitudinal section of the slot antenna of the third embodiment; Figures 12 to 15 show sectional examples of a slot antenna according to a fourth embodiment of the present invention; FIG. 16 is a perspective sectional view of the slot antenna shown in FIG. 15;

  FIG. 17a is a fragmentary perspective view

  of a slot antenna according to a fifth embodiment of the present invention; Fig. 17b is an explanatory diagram showing an electric field distribution in the slot antenna of Fig. 17a; Fig. 18a is a fragmentary sectional view of a slot antenna according to a sixth embodiment of the present invention; Fig. 18b is a plan view of a metal plate used in the slot antenna of Fig. 18a; Fig. 19 is a fragmentary sectional view of a slot antenna according to a seventh embodiment of the present invention; Fig. 20 is a fragmentary sectional view of an antenna according to an eighth embodiment of the present invention; Fig. 21 is a perspective sectional view of a slot antenna according to a ninth embodiment of the present invention; Figures 22 and 23 are schematic sectional views of modifications of the slot antenna of the ninth embodiment; Fig. 24 is a sectional perspective view showing another modification of the slot antenna of the ninth embodiment; FIGS. 25 to 28 are diagrams representing slits and electric fields radiated from slot antennas; Fig. 29 is a perspective view of a horn waveguide; FIG. 30 is a sectional perspective view of a modification of a horn waveguide; Fig. 31a is a perspective view of a slot antenna according to a tenth embodiment of the present invention, having parabolic reflectors; - Figure 31b is a perspective sectional view of the slot antenna of the tenth embodiment; Fig. 32 is a plan view of a horn waveguide of the slot antenna; - Figure 33a is a perspective view of the slot antenna shown in orthogonal coordinates; - Figures 33b and 33c are explanatory diagrams of the slot antenna; Fig. 34 is an enlarged perspective view showing a portion of the slot antenna; Fig. 35 is a sectional view of the slot antenna; FIG. 36 is a perspective sectional view of a slot antenna according to an eleventh embodiment; FIGS. 37 and 38 show sectional perspective views of modifications of the eleventh embodiment; Figure 39 is a perspective sectional view of a slot antenna according to a twelfth embodiment; Figures 40 to 43 are plan views of examples of slot arrangements; FIG. 44 is a perspective sectional view of a conventional circular slot of the coaxial cable type; and - Figure 45 is a diagram explaining the

  wave propagation in the conventionally slotted antenna

  represented in cylindrical coordinates.

  Referring to FIGS. 1 and 2, a slot antenna according to the present invention comprises a rectangular waveguide W and a horn waveguide 5 connected to the rectangular waveguide W at a power supply opening. 2 of it. The rectangular waveguide W comprises opposite rectangular metal guide plates 3 and 4, and metal side guide plates 1, 7 and 8 to form a rectangular waveguide space S. The upper guide plate 3 includes a number of radiation slits

  15, arranged in rows. The rows are coaxial-

  arranged and each slot is arranged perpendicularly

  the inside of the side plate 1 of the rectangular waveguide W, a terminal resistor 6 is provided as shown in FIG.

figure 2.

  In the rectangular waveguide W, the electromagnetic wave is propagated in TE10 mode represented by orthogonal coordinates as indicated in FIG.

  Figure 3. In Figure 3, the dashed lines H represent

  Magnetic lines of force and E-lines represent lines of electric force at each half-wavelength (1/2%). Since electric lines of force having the same direction occur at each wavelength (X0), it is easy to form slots to radiate the electric force. Depending on the antenna, not only the circularly polarized wave but also the linear polarization can be

high yielding radiates.

  If slots are formed on the side plate 8, the magnetic force is radiated out of the slots. In such an antenna, slots are arranged in parallel

  to the axis of the rectangular waveguide.

  In the waveguide 5, the wave is propagated coaxially around a center 0 in a power supply input as shown in FIG. 4. As a result, there is a phase difference between the travel distance of the center L wave and an exit aperture 22 along the (B-B ') axis and

  the distance of travel of the wave along a side 21.

  In order to compensate for the difference in phase, the slots 15 are arranged along coaxial circular lines, around the center 0. Thus, the electric forces having

  the same phase can be emitted from the slots.

  The remaining energy in the waveguide W is absorbed in the terminal resistor 6 at the plate

lateral end 1.

  Referring to Fig. 7a showing a second embodiment of the present invention, the horn waveguide 5 comprises, at the output thereof, a dielectric lens antenna 19a. The lens antenna has a semicircular shape in planar view so that the phase difference of the wave can be compensated. The operation and the effect of the embodiment are the same as for the first mode of

IF achievement.

  The horn waveguide 5 shown in FIG. 7b comprises a lens antenna 19b made of a number of metal plates, and the horn waveguide 5 of FIG. 8 has a delay wave device 13 in the form of a ribbed metal plate. By such means, a plane passing from the equiphase parts becomes flat. Thus, the slots 15 can be arranged in parallel as shown in FIG.

figure 9.

  Figure 5 shows a density distribution

  of the antenna according to the first embodiment of

  The energy density is reduced to the end side plate 1 because of the energy radiation of the slots 15, so that the antenna gain is reduced. A third embodiment shown in FIG. 10 is to radiate the energy uniformly. The guide plate 4 without slots is inclined with respect to the guide plate 3 to reduce the width

  space S in the waveguide to the side plate

  Thus, the energy is substantially evenly distributed as shown in FIG. 11, increasing by

so the antenna gain.

  Referring to Fig. 6, a dotted line D represents a distribution of the electric field in the transverse plane in which the electrical force is reduced to both sides 7 and 8. Each of the waveguides as the fourth embodiment shown in Figures 12 and 14 has a V-shaped guide plate 4, and each waveguide shown in Figures 13, 15 and 16

  has a circular guide plate 4 so that the dis-

  tribution of the electric field can be unified.

  In a fifth embodiment of FIG. 17a, two metal plates 18 are provided in

  the waveguide W adjacent to the side plates 7 and 8.

  Each plate 18 is fixed to the plate 4 forming an interval between the plate 3 in order to strangle the waveguide to produce a clean impedance. Thus, the distribution of the electric field can be unified as

represented in FIG. 17b.

  A waveguide of the sixth embodiment shown in Figure 18a comprises an intermediate metal plate 17 having a large number of slots and holes 16. By adjusting the shape and density of the holes as shown in Figure 18b, the density of energy in

  a space S1 and the electric field can be uniform

distributed.

  In the seventh embodiment shown in FIG. 19, an adapter element 11 is provided on the end plate 1 instead of the terminal resistor 6 of the first embodiment. The wave striking the matching element is reflected to be added to the radiated waves of the end slots, thus equalizing

the distribution of energy.

  A waveguide according to an eighth embodiment shown in FIG. 20 comprises a delay wave device 13 formed by a ribbed plate or made of a dielectric. By controlling the phase constant of the wave, it is possible to adjust the direction of the radiation and the energy density to improve the

  directivity and gain of the antenna.

  Next to the antenna shown in Figure 21 as

  ninth embodiment, the rectangular waveguide

  W is superimposed on the horn waveguide 5 to form a compact construction. The guide plate 4 is shortened, so that the opening 22 of the horn waveguide 5 is connected to the opening 2 of the rectangular waveguide W, thereby forming a U-shaped connection. and 23 represent U-shaped connections, respectively. In each of the connections, an inclined guide element 12 is provided at each corner, so that the wave is rotated from 1800

  without reflecting the wave, effectively radiating energy.

  FIG. 24 represents a modification of the antenna of FIG. 21. The antenna comprises a reflector

  parabolic 23 to the U-shaped connection.

  With the wave through the parabolic reflector 23, the phase difference is compensated for forming an equiphase flat wave plane. Thus, the slots 15 can be

arranged in parallel.

  Fig. 25 shows the arrangement of slots at wavelength intervals L0 '. The slots 15 shown in Figs. 26 and 27 are formed at half-wavelength intervals 70/2 and 450 relative to the waveguide axis. Slots 15 on adjacent rows are inverted to be 900 relative to one another. Thus, components P having the same direction are added to each other, thereby increasing the radiated energy. Since the

  density of the slots is increased, the output of

  ture can be increased to improve the gain of the antenna. The slots shown in Figures 25 to 27 are arranged for linear polarization. The slots shown in FIG. 28 are arranged for the wave

circularly polarized.

  Fig. 29 shows a modification of the horn waveguide 5. The horn waveguide comprises a curved guide 14. The horn waveguide 5 shown in Fig. 30 comprises a coaxial cable 34 as a power supply. Another power supply such as a ribbed waveguide and a loop coupling can

to be used.

  Referring to Figures 31a and 31b showing a tenth embodiment, the antenna comprises two rectangular waveguides W1, W2 and two horn waveguides. The rectangular waveguides are formed by opposed guide plates 31, 32, side plates 33, 33a, and a partition 37 having end resistances on the opposite sides thereof, so that two guide gaps are provided. S1 and S wave are formed. The horn waveguide includes guide plates 32 and 34a to form two horn waveguide spaces A1 and A2 which are symmetrically separated by an adapter member 35. Thus, two antennas are symmetrically formed. A power waveguide 34 having a waveguide gap A is connected to a central portion of the antenna that is in communication with the spaces A1 and A2.

  by power supply openings.

  Each connection C having an interval D has a side plate 33a having a shape in semicircular or polygonal section and has a parabolic reflector. The parabolic reflector is formed in

  moving a parabola along the semi-

  Circular 33a. In other words, the parabolic reflector has a parabola at each cross section

  of the semicircular plate 33a. As a result, the reflection

  parabolic dish is different from the satellite dish

  which is formed by the rotation of a parabola.

  The wave in space A1 (A2) in the cornet waveguide propagates in circular mode around 0 as

  represented in FIG. 32, having a phase difference.

  The wave is reflected by the parabolic reflector,

  so that the phase difference is compensated for

  It is also possible to obtain distances of equal displacement or travel with respect to the Y axis as shown in FIG. 33b. Moreover, as shown in FIG. 33c, the wave is reflected to the U-shaped reflector in parallel. The displacement distances with respect to the Z axis are equalized. So the slots 31a

  can be arranged in parallel.

  Since the wave reflected from the U-shaped reflector passes the space S1 different from the space A1 (FIG. 33c), it is possible to prevent the reduction of the gain due to the blocking which occurs in a parabolic antenna at

double reflection.

  As for the size of the slot 33a, the slot length is about half a wavelength (1/2 X 0) and the width is smaller than the wavelength. It is preferred that the gap h between the slots be smaller than a free-space wavelength θ in order to reduce the side lobe of the antenna, for example from 0.9 to 0.5. However, it is impossible to transmit the wave of slots arranged at such intervals. In order to emit the wave, a ribbed plate 36 as a delay wave device is mounted on the guide plate 32 as shown in FIG. 35. By delaying the wave, the same phase waves can be emitted from the waves.

  slots arranged at small intervals. Although the

  valle h is reduced, the length of the slot 31a is about half a wavelength. It is possible to increase the ratio of the available area of the slits 31a to the cross-sectional area of the rectangular waveguide having a parabolic reflector, thus improving the opening efficiency. For example, if a rectangular parabolic reflector waveguide has an axial length of 80 cm and a length of the long side of the rectangle of 60 cm, the interval h is 0.8 × 0, and the frequency of the wave is of 12 GHz, 1,600 parallel slots can be

  made on the radiation plan.

  Referring to Fig. 36 showing an eleventh embodiment, a single horn waveguide having a connection C is disposed in parallel with the rectangular waveguides W1 and W2. The connection C has a parabolic reflector and the wave is brought from a central part between the waveguides W1 and W2. As a result, the terminal resistors 37 are provided at opposite ends of the antenna. FIGS. 37 and 38 show modifications of the eleventh embodiment, in which each connection C is arranged perpendicular to the

rectangular waveguide.

  Fig. 39 shows a modification of the tenth embodiment of Figs. 31a and 31b. A coaxial cable 38 is connected to the antenna at a central portion between the horn waveguides to emit waves to the A1 and A2 horn waveguide spaces through

  power supply input openings.

  Figures 40 to 43 show slit arrangements 31a. The antenna of FIG. 40 is made to radiate the binary polarization and the antenna of FIG. 41 is made to radiate the circularly polarized wave. In the antenna shown in Figure 42, four slots encircled by a line form a unit to radiate a linear polarization and a certain

  number of units are arranged in rows and columns.

Claims (12)

R E V E N D I C A T I 0 N S   1. Antenna with slots, characterized in that it comprises: a rectangular waveguide (W) having metal plates (1, 3, 4, 7, 8) for forming a guide space (S) of rectangular wave; a horn waveguide (5) connected to the rectangular waveguide to communicate therewith a   cornet waveguide to the rectangular waveguide space   gular, and having a power supply input opening 2 at one end thereof; the rectangular waveguide having a number of wave radiation slots (15) on one metal plates.   2. Antenna according to claim 1, characterized in that the rectangular waveguide comprises a terminal resistor (6) to an end plate thereof. 3. Antenna according to claim 1, characterized in that the rectangular waveguide comprises means of adaptation (11) to an end plate thereof to increase the transmitted wave energy of the slots   (15) adjacent to the end plate.   4. Antenna according to claim 1, characterized in that a metal plate opposite to the metal plate having the slots (15) comprises a wave means   delay (13) to delay the propagated wave.   5. Antenna according to claim 1, characterized in that the rectangular waveguide space is reduced to an end plate in width between the metal plate having the slots and an opposite metal plate. 6. Antenna according to claim 1, characterized in that the rectangular waveguide comprises two metal plates adjacent to the side plates, each of which is fixed to a plate opposite to the plate having the slots to effect a throat of the guide rectangular waveform to produce a proper impedance, thereby distributing the electric field uniformly. 7. Antenna according to claim 1, characterized in that the slots are arranged perpendicularly   to the axis of the rectangular waveguide.   8. Antenna according to claim 1, characterized in that the rectangular waveguide and the horn waveguide are arranged so that the axes of the two   waveguides are arranged on an axial line.   9. Antenna according to claim 1, characterized in that the rectangular waveguide and the waveguide   in cornet are superimposed on one another.   10. Antenna with slots, characterized in that it comprises: a rectangular waveguide (W) surrounded by metal plates (1, 3, 4, 7 and 8) to form a space (S) of the guide rectangular wave; a horn waveguide (5) connected to the rectangular waveguide for communicating a horn waveguide space therein to the rectangular waveguide space (S), and having an aperture of power supply input at one end thereof; the rectangular waveguide having a number of wave radiation slots (15) on one of the metal plates; a parabolic reflector (23) provided between the horn waveguide space and the rectangular waveguide space for reflecting the wave to the rectangular waveguide so that an equiphase plane of the wave can be flattened.   11. Antenna according to claim 10, characterized in that the rectangular waveguide comprises a terminal resistance (6) to a plate end of it.   12. Antenna according to claim 10, characterized in that a metal plate opposite to the metal plate having the slots (15) comprises a   delay wave means (13) for delaying the propagated wave.