JPH04301902A - Horn antenna - Google Patents

Abstract

PURPOSE:To obtain the horn antenna especially for a large antenna or with a small diameter used as the primary horn of a reflection mirror antenna or as a horn antenna unit. CONSTITUTION:At the horn antenna equipped with a hollow waveguide 1, dielectric mount horn 11 filling a dielectric with the feeding side diameter smaller than the diameter of the hollow waveguide 1 and feeding side matcher 10 to connect the hollow waveguide 1 and the feeding side of the dielectric mount horn 11, the feeding side matcher 10 is composed of a tapered waveguide 10a, which diameter is reduced from the hollow waveguide 1 side to the dielectric mount horn 11, and a tapered dielectric 10b, which diameter is reduced from the dielectric mount horn 11 side to the hollow waveguide 1, inserted along the central axis of the hollow waveguide 1. Thus, a radiation pattern having wide beam width suppressing the degradation of an electric characteristic can be realized.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is used as a primary horn of a reflector antenna or as a single horn antenna.
It particularly relates to large antennas or small diameter horn antennas.

0002

2. Description of the Related Art Conventionally, there has been a device of this type as shown in FIG. This figure is from Japanese Patent Application Laid-Open No. 62-1909.
In the figure, 1 is a hollow circular waveguide, 2 is a mode generator, 3 is a dielectric-loaded horn,
4 is a dielectric matching element. Hollow circular waveguide 1 is TE1
1 mode, and mode generator 2 generates TE11 mode and TM11 mode. Figures 6(a), (b), (
c) shows the electric field distribution of each mode in the cross section of the dielectric-loaded horn 3. 6 shows the electric field distribution in the TE11 mode, 7 shows the electric field distribution in the TM11 mode, and 8 shows the electric field distribution obtained by adjusting and combining the two modes. The dielectric-loaded horn 3 adjusts the amplitude and phase of the two modes, as shown in the same figure (c).
A distribution like this is obtained, and the beam widths of the E-plane and H-plane of the radiation pattern are matched. The diameter and length of the dielectric matching element 4 are adjusted in order to reduce reflection due to impedance mismatch between the hollow circular waveguide 1 and the mode generator 2. The length L1 of the dielectric-loaded horn 3 is adjusted so that the beam widths of the E-plane and the H-plane match even if a mismatch occurs between the characteristic impedance of each mode and the free space impedance at the aperture plane 5.

[0003] The electromagnetic field near the dielectric matching element 4 is disturbed by waves reflected by the waveguide discontinuity 9 . In order to reduce such disturbances in the electromagnetic field, it is necessary to equivalently use the combined area of the dielectric matching element 4 and the waveguide discontinuity portion 9 as a matching box.

It is also known that the radiated electromagnetic field is determined from the electromagnetic field distribution at the aperture surface 5 by the aperture distribution method, and the radiated power density is 1/2 of the maximum radiation direction.
The angle between the two directions, that is, the beam width Θ[r
ad], the aperture diameter D1, and the wavelength λ, if reflection by the aperture surface 5 is ignored, the relationship is as follows.

Θ=k1 (λ/D1)

(1)

[0006] Here, k1 is a constant determined by the aperture distribution. From this, the beam width Θ for the frequency used is approximately determined by the aperture diameter D1 (physical dimension), and the smaller the aperture, the wider the beam width.
It can be seen that a broad radiation pattern can be obtained. Further, the opening diameter D1 of the dielectric-loaded horn 3 is determined as follows depending on the conditions under which the TM11 mode propagates in the dielectric-loaded horn 3.

D1 > K2 λ/εr11
/2
(2)

Here, εr1 is the relative permittivity of the dielectric of the dielectric-loaded horn 3, and K2 is 1.
It is 2. By using a dielectric material with a high permittivity,
The opening diameter D1 can be made smaller.

Therefore, in the conventional device described above, a broad radiation pattern can be obtained by reducing the aperture diameter, and the beam widths of the E-plane and H-plane of the radiation pattern are made to match by using multiple modes.

0010

[Problem to be Solved by the Invention] Since the conventional horn antenna is constructed as described above, in order to realize a radiation pattern with a wide beam width, a dielectric material with a high permittivity is used to reduce the aperture diameter. Therefore, there was a problem in that impedance mismatching occurred and electrical characteristics deteriorated. Furthermore, since multiple modes are used to match the beam widths of the E-plane and H-plane of the radiation pattern, there is a problem in that it is necessary to optimally adjust the amplitude and phase of each mode.

[0011] This invention was made to solve the above-mentioned problems, and it is possible to realize a radiation pattern with a wide beam width without the need to adjust the amplitude and phase of the mode while suppressing the deterioration of electrical characteristics. The purpose is to obtain a horn antenna.

0012

[Means for Solving the Problems] A first horn antenna of the present invention includes a tapered waveguide whose diameter decreases from the hollow waveguide side toward the dielectric-loaded waveguide, and a hollow waveguide. It is equipped with a power feeding side matching device that is inserted along the central axis and is configured with a tapered dielectric whose diameter decreases from the dielectric-loaded waveguide side toward the hollow waveguide.

Further, the second horn antenna of the present invention has the following features:
An opening side matching device made of a dielectric material having a dielectric constant different from that of the waveguide and the above-mentioned dielectric is provided on the opening side of the dielectric-loaded waveguide, and this opening side matching device is located approximately 4 minutes of the tube wavelength from the opening surface. The thickness is set to 1.

Further, the third horn antenna of the present invention has the following features:
An opening-side matching device made of a dielectric having a higher dielectric constant than the waveguide and the dielectric is provided on the opening side of the dielectric-loaded waveguide, and this opening-side matching device is connected to the dielectric-loaded waveguide. It is inserted into the center along the central axis.

[0015] Furthermore, the fourth horn antenna of the present invention has the following features:
A flange made of a conductor is provided around the outer periphery of the opening, and a choke consisting of a ring-shaped groove with a depth of approximately 1/4 wavelength is formed on this flange.

[0016]

[Operation] Since the first horn antenna is equipped with a feeding-side matching device that has a shape that changes smoothly and has a constant mode characteristic impedance, deterioration of electrical characteristics can be suppressed.

[0017] Since the second horn antenna is provided with an aperture side matching device made of a dielectric material having a different permittivity on the aperture side, deterioration of electrical characteristics can be suppressed.

Since the third horn antenna is provided with a dielectric material on the opening side that has a high permittivity at the center, the E
The beam widths of the H-plane and the H-plane can be matched.

Since the fourth horn antenna has a flange with a choke on the opening side, the beam widths of the E plane and the H plane can be matched.

[0020]

[Example] Example 1. FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention, and 1 is the same as the conventional device shown in FIG. In the figure, 10 is a matching device on the feeding side, 10a is a tapered circular waveguide, 10b is a tapered dielectric, 11 is a dielectric-loaded horn, 11a is a circular waveguide, and 11b is made of the same material as the tapered dielectric 10b. It is a dielectric rod. The tapered circular waveguide 10a is set to have a diameter gradually smaller than that of the hollow circular waveguide 1 and is connected to the hollow circular waveguide 1, and the circular waveguide 11a is connected to the hollow circular waveguide 1. It is set to have the same diameter as the smaller diameter of the pipe 10a and is connected.

Next, the operation will be explained. The hollow circular waveguide 1 having an inner diameter d guides the excited fundamental mode TE11 mode. The power supply side matching box 10 is
A tapered circular waveguide 10a and a tapered dielectric 1 are arranged so that the characteristic impedance of the fundamental mode is constant in the propagation direction.
Impedance matching is achieved by adjusting the taper shape of 0b. The dielectric-loaded horn 11 is set to have a characteristic impedance equal to the characteristic impedance of the fundamental mode of the hollow circular waveguide 1. Although a mismatch occurs between the characteristic impedance of the mode and the free space impedance at the aperture surface 5, the lengths L2 and L are set so as to cancel the reflected waves from the reflecting mirror at the aperture surface 5 and the surfaces 12 and 13 at both ends of the taper.
Match by optimizing 3. Further, the dielectric constant εr2 is determined as follows by considering an equivalent line having the same transmission characteristics as the fundamental mode so as to obtain the desired aperture diameter D2.

εr2=1+K3λ2(D2
-2-d-2)
(3)

[0023] Here, K3 is 0.3 to 0
．． The value is 4. In addition, the aperture diameter D2 is a dimension that allows only the fundamental mode to propagate, and K2 in equation (2) is 0.
．． It becomes 6.

In addition, the power feeding side matching device 10 is provided in such a shape that the tapered circular waveguide 10a and the tapered dielectric 10b change smoothly, and is similar to the waveguide discontinuous portion 9 of the conventional device shown in FIG. Since it does not have such a discontinuous shape, it can match over a wide band and suppress the generation of higher-order modes.

The opening diameter D2 can be made smaller by using a dielectric material with a high dielectric constant. Compared to the conventional device shown in Fig. 5, due to the difference in K2 in equation (2), a smaller aperture diameter can be achieved by using a material with the same dielectric constant, and a smaller aperture diameter can be achieved by making the aperture diameter the same. Therefore, deterioration of electrical characteristics can be suppressed.

Therefore, in the first embodiment shown in FIG. 1, the deterioration of the electrical characteristics is suppressed by the power supply side matching device.

Example 2. In addition, FIG. 2 shows Example 2 of the present invention.
1, 1 is the same as the conventional device shown in FIG. 5, and 10 and 11 are the same as the first embodiment shown in FIG. In the figure, 14 is an opening-side matching device, 14a is a circular waveguide, and 14b is a dielectric rod 11b with a relative permittivity εr3 different from that of the dielectric rod 11b.
It is a dielectric material. The opening-side matching device 14 is provided to match the characteristic impedance of the mode of the dielectric-loaded horn 11 and the free space impedance, and is
By adjusting the dielectric constant of the tube, it is equivalently made into a quarter-wavelength transformer, and the thickness L4 is approximately one-fourth of the tube wavelength. The relationship between the relative permittivity εr2 of the dielectric rod 11b and the relative permittivity εr3 of the dielectric 14b is 1<εr2<εr3 since it is equivalently a quarter wavelength transformer. Other operations operate in the same manner as in the first embodiment shown in FIG. 1, and have similar effects.

Therefore, the second embodiment shown in FIG. 2 suppresses the deterioration of the electrical characteristics by providing the opening side matching device.

Example 3. In addition, FIG. 3 shows Example 3 of the present invention.
1, 1 is the same as the conventional device shown in FIG. 5, and 10 and 11 are the same as the first embodiment shown in FIG. In the figure, 15 is a matching device on the opening side, 15a is a circular waveguide, 15b is a dielectric having a higher dielectric constant than the dielectric rod 11b, and 15c is a dielectric formed by hollowing out the dielectric rod 11b. Since the electric field distribution on the aperture surface 5 is concentrated in a portion with a high dielectric constant, an electric field distribution as shown in FIG. 6(c) can be obtained. Therefore, the beam widths of the E plane and the H plane of the radiation pattern can be matched by one mode. Other operations operate in the same manner as in the second embodiment shown in FIG. 2, and have similar effects.

Therefore, since the third embodiment shown in FIG. 3 is equipped with an aperture side matching device, there is no need to adjust the amplitude and phase of the mode, and the beam widths of the E plane and H plane can be adjusted by one mode. Can be matched.

Example 4. 4(a) and 4(b) are schematic configuration diagrams showing a fourth embodiment of the present invention, in which 1 is the same as the conventional device shown in FIG. 5, and 10, 11, and 14 are the same as the conventional device shown in FIG.
This is the same as Example 2 shown in . In the figure, 1
6 is a flange, and 17 is a choke consisting of a ring-shaped groove. The flange 16 is provided on the outer periphery of the opening,
The choke 17 has a groove having a depth of approximately 1/4 wavelength. FIG. 2B shows a schematic diagram of the fundamental mode electric field distribution in the cross section of the aperture surface 5 and the choke 17. Due to the effect of the electric field of the choke 17, the electric field distribution on the E-plane and the H-plane can be made almost equal, and the beam width of the radiation pattern can be made almost equal on the E-plane and the H-plane. Further, the same effect can be obtained when the choke 17 is formed from a plurality of rings. Regarding other operations, Example 2 shown in FIG.
It acts in the same way and has the same effect.

Therefore, since the fourth embodiment shown in FIG. 4 is equipped with a choke, it is not necessary to adjust the amplitude and phase of the mode, and the beam widths of the E plane and the H plane can be matched by one mode. It is possible to realize a radiation pattern with a wide beam width by using a small aperture surface.

[0033]

[Effects of the Invention] As explained above, according to the present invention,
Since the power feeding side matching device has a shape that changes smoothly and has a constant mode characteristic impedance, deterioration of electrical characteristics can be suppressed. Further, since the aperture-side matching device is provided, deterioration of electrical characteristics can be suppressed and the beam widths of the E-plane and the H-plane can be matched. In addition, since it is equipped with a flange with a choke on the opening side, the beam widths of the E and H planes can be matched, resulting in a horn antenna that can realize a radiation pattern with a wide beam width using a small diameter horn. It will be done.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a conventional horn antenna.

FIG. 6 is a diagram showing an electric field distribution in a cross section of a conventional horn antenna.

[Explanation of symbols]

1 Hollow circular waveguide 2 Mode generator 3 Dielectric loaded horn 4 Dielectric matching element 5 Aperture surface 6 TE11 mode electric field distribution 7 TM11 mode electric field distribution 8 Combined electric field distribution 9 Waveguide discontinuity 10 Feed side Matching device 10a Tapered circular waveguide 10b Tapered dielectric 11 Dielectric loaded horn 11a Circular waveguide 11b Dielectric rod 12 Interface 13 between hollow circular waveguide and feeding side matching device
Interface 14 between the power supply side matching box and the dielectric-loaded horn
Opening side matching device 14a Circular waveguide 14b Dielectric 15 with relative permittivity εr3 Opening side matching device 15a Circular waveguide 15b Dielectric 15c with relative permittivity εr2 Dielectric 16 with relative permittivity εr3 Flange 17 Choke

Claims (4)

[Claims] Claim 1: A hollow waveguide as a feeding waveguide, and a dielectric-loaded waveguide which is open at one end, has a diameter on the feeding side smaller than the diameter of the hollow waveguide, and is filled with a dielectric. and a horn antenna comprising a feeding side matching device that connects the hollow waveguide and the feeding side of the dielectric loaded waveguide, wherein the feeding side matching device connects the dielectric material from the hollow waveguide side to the feeding side matching device. a tapered waveguide whose diameter decreases toward the loaded waveguide;
and a tapered dielectric that is inserted along the central axis of the hollow waveguide and whose diameter decreases from the dielectric-loaded waveguide side toward the hollow waveguide. horn antenna. 2. A hollow waveguide as a feeding waveguide, and a dielectric-loaded waveguide which is open at one end, has a diameter on the feeding side smaller than the diameter of the hollow waveguide, and is filled with a dielectric. and a horn antenna equipped with a feed-side matching device that connects the hollow waveguide and the feed side of the dielectric-loaded waveguide, the waveguide and Equipped with an opening-side matching device made of a dielectric with a dielectric constant different from the above-mentioned dielectric,
A horn antenna characterized in that the aperture-side matching device is set at a thickness of about one-fourth of the tube wavelength from the aperture surface. 3. A hollow waveguide as a feeding waveguide, and a dielectric-loaded waveguide which is open at one end, has a diameter on the feeding side smaller than the diameter of the hollow waveguide, and is filled with a dielectric. and a horn antenna equipped with a feed-side matching device that connects the hollow waveguide and the feed side of the dielectric-loaded waveguide, the waveguide and An opening-side matching device made of a dielectric material having a higher dielectric constant than the dielectric material is provided, and the opening-side matching device is inserted into the dielectric-loaded waveguide partially along the central axis. A horn antenna featuring 4. A flange made of a conductor is provided around the outer periphery of the opening, and a choke made of a ring-shaped groove with a depth of approximately 1/4 wavelength is formed on the flange. Horn antenna according to 2 or 3.