JPH0946129A - Phased array antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothen change in the gain of an array antenna in the case of beam scanning by arranging a radio wave absorber at a position on an element antenna board where no element is in existence, thereby suppressing multiple reflection with a radome. SOLUTION: This antenna system is provided with an element antenna board 2 on which plural element antennas 1 are arranged, a phase shifter 3 connecting to the element antennas 1, a feeder circuit 4, a radome 5 arranged in front of the element antenna board 2 in parallel with the board, a radio wave absorbing body 6, which is arranged onto the element antenna board 2 where no element antenna 1 is in existence. An electromagnetic emitted from each element antenna 1 at a wide angle is reflected in the radome 5 and the reflected electromagnetic wave is absorbed by the radio wave absorbing body 6 without being reflected in the antenna board 6. As the element pattern of the element antennas 1, the element pattern without a ripple and not affected by the multiple reflection between the antenna element 2 and the radome 5 is obtained and a gain change at beam scanning time is smoothened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phased array antenna device having a plurality of element antennas.

[0002]

2. Description of the Related Art A conventional phased array antenna device will be described. FIG. 12 is a diagram showing a conventional phased array antenna device, in which 1 is an element antenna, 2 is an element antenna substrate which constitutes the element antenna 1, 3 is a phase shifter,
Reference numeral 4 is a feeding circuit, and 5 is a radome arranged in parallel with the element antenna substrate 2.

Next, the operation will be described. Since the antenna is reciprocal for transmission and reception, a case where the antenna is for transmission will be described. The signal input to the power feeding circuit 4 is distributed to the number of elements by the power feeding circuit 4, the phase of each signal is controlled by each phase shifter 3, and then the signal is radiated into space from each element antenna 1.

The electromagnetic waves radiated into the space enter the radome 5 arranged in parallel with the element antenna substrate 2.

FIG. 13 shows a sectional view of the radome 5. t is the thickness of the radome 5, and εr is the relative dielectric constant of the radome.

Here, the optimum thickness t of the radome 5 can be obtained by calculating "equation 1" according to the wavelength λ used.

[0007]

[Equation 1]

Here, θ is the angle that minimizes the transmission loss at the time of incidence, but in the phased array antenna, θ is the center of the beam scanning angle, so the beam direction is relative to the front of the antenna, that is, the radome 5. It is the angle of vertical incidence.

Although the optimum thickness can be obtained from "Equation 1", in the case of the radome 5 having a constant thickness t, the radome 5
The transmission loss and the reflection loss of the radome 5 change depending on the angle of incidence on the.

FIG. 14 shows an example of transmission loss and reflection loss with respect to the incident angle of the radome 5. In the figure, the solid line (a) shows the transmission loss when the E-plane is incident, the broken line (b) shows the transmission loss when the H-plane is incident, the broken line (c) shows the reflection loss when the E-plane is incident, and the chain line d shows the reflection loss when the H-plane is incident.

Since the element antenna 1 on the element antenna substrate 2 radiates a very broad radiation, the radome 5
Also, electromagnetic waves are incident on a wide angle range.

In such a case, an electromagnetic wave incident on the radome 5 at a large incident angle is reflected on the antenna substrate 2 because the radome 5 is largely reflected.

The reflected electromagnetic wave is reflected again by the antenna substrate 2 and enters the radome 5.

At this time, since the antenna substrate 2 and the radome 5 are parallel to each other, the directions of the reflected electromagnetic wave and the electromagnetic wave transmitted through the radome coincide with each other, and multiple reflection occurs.

FIG. 15 is a diagram showing the state of multiple reflection.

From the figure, it can be seen that the direction of the electromagnetic wave transmitted through the radome 5 and directly emitted coincides with the direction of the electromagnetic wave Er emitted after being multiply reflected.

Therefore, a ripple is generated in each element pattern due to the phase relationship between the two electromagnetic waves.

FIG. 16 shows an example of the radiation pattern of the element antenna 1 when multiple reflections exist on the element antenna substrate 2 and the radome 5. In the figure, the solid line E is the E-plane pattern with the radome 5, the broken line F is the H-plane pattern with the radome 5, and the broken line G is the E-plane pattern without the radome 5.
The surface pattern and the alternate long and short dash line 4 are the H surface pattern when the radome 5 is not provided.

Here, the element antenna substrate 2 and the radome 5
Since they are placed in parallel, the same element pattern is used for all the elements.

Therefore, when the beam is scanned, the gain of the array antenna depends on the element pattern in the beam direction, so that the gain changes according to the shape of the element pattern.

[0021]

In the conventional phased array antenna apparatus, since multiple reflection occurs between the element antenna substrate and the radome as described above, the array antenna gain during beam scanning is accompanied by the ripple of the element pattern. There was a problem of large fluctuations.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a phased array antenna device in which the array antenna gain changes smoothly during beam scanning.

[0023]

A phased array antenna device according to a first embodiment of the present invention has a radio wave absorber arranged on a portion of an element antenna substrate where an element antenna is not present.

Further, in the phased array antenna apparatus according to the second embodiment of the present invention, the electromagnetic wave absorber is arranged in a portion of the element antenna substrate where the element antenna does not exist, and the element antenna excited by linearly polarized wave radiates. The grid that reflects the unnecessary polarized waves of the electromagnetic wave is arranged on the radome.

Further, in the phased array antenna apparatus according to the third embodiment of the present invention, the electromagnetic wave absorber is arranged on a portion of the element antenna substrate where the element antenna does not exist, and the shape of the radome is different from that of the element antenna substrate. It is a thing.

Further, in the phased array antenna apparatus according to the fourth embodiment of the present invention, the element antenna substrate on a portion where the element antenna does not exist on the element antenna substrate is removed,
The electromagnetic wave absorber is arranged in the removed portion.

Further, in the phased array antenna apparatus according to the fifth embodiment of the present invention, the resistance film and the protective layer are arranged on a portion of the element antenna substrate where the element antenna does not exist, and the element antenna substrate thickness of the portion is 1/4. It is configured to be a wavelength wave absorber.

[0028]

According to the first embodiment of the present invention, since the electromagnetic wave absorber is arranged in the portion on the element antenna substrate where the element antenna does not exist, multiple reflection between the element antenna substrate and the radome is eliminated, and the array during beam scanning is eliminated. The change in antenna gain can be smoothed.

Further, according to the second embodiment of the present invention, the electromagnetic wave radiated from the element antenna excited by the linearly polarized wave is arranged while the radio wave absorber is arranged in the portion on the element antenna substrate where the element antenna does not exist. Since the grid that reflects the unnecessary polarized wave of is arranged on the radome, the change of the array antenna gain during beam scanning can be smoothed and the cross polarized wave radiated from the element antenna can be suppressed. .

Further, according to the third embodiment of the present invention, since the radio wave absorber is arranged in the portion on the element antenna substrate where the element antenna does not exist, and the shape of the radome is different from the element antenna substrate, The influence of multiple reflection between the antenna substrate and the radome can be changed for each element antenna, the change in the array antenna gain during beam scanning can be smoothed, and the mechanical strength of the radome can be improved.

Further, according to the fourth embodiment of the present invention, the element antenna substrate of the element antenna substrate where the element antenna does not exist is removed, and the electromagnetic wave absorber is arranged in the removed portion. The change in the array antenna gain during beam scanning can be smoothed, and the height of the radio wave absorber can be reduced, so that the blocking effect during radio wave radiation can be eliminated.

According to the fifth embodiment of the present invention, the resistive film and the protective layer are arranged on the surface of the element antenna substrate where the element antenna is not present on the element antenna substrate, and the resistive film, the protective layer and the element antenna substrate are arranged. Since the quarter-wave absorber is constituted by the ground conductor, the change in the array antenna gain during beam scanning can be smoothed, and the blocking effect at the time of radio wave emission can be eliminated. , Can be easily crafted.

[0033]

【Example】

Embodiment 1 FIG. FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention,
FIG. 2 is a diagram showing the connection relationship of each device of the present invention.

In the figure, 1 is an element antenna, 2 is an element antenna substrate constituting the element antenna, 3 is a phase shifter connected to the element antenna 1, 4 is a feeding circuit, and 5 is a radome parallel to the element antenna substrate 2. , 6 are element antenna substrates 2
2 is a radio wave absorber arranged in a portion excluding the element antenna 1.

Next, the operation will be described. The electromagnetic wave input to the power feeding circuit 4 is distributed to each element antenna by the power feeding circuit 4, and the phase is controlled by the phase shifter 3.
More radiated into space.

The electromagnetic wave radiated into the space is incident on the radome 5 arranged in parallel with the element antenna substrate 2.

Here, since the element antenna 1 radiates a very broad radiation, electromagnetic waves are incident on the radome 5 up to a very large incident angle.

As for the incident characteristic of the radome 5, as the incident angle increases, the reflection increases, so that the electromagnetic wave radiated from the element antenna 1 in a wide angle is reflected by the radome 5.

On the other hand, since the electromagnetic wave absorber 6 is arranged on the front surface of the element antenna substrate 2 except the element antenna 1, the electromagnetic wave reflected by the radome is not reflected by the antenna substrate 2. It is absorbed by the radio wave absorber 6.

As a result, the element pattern of the element antenna 1 is not affected by the multiple reflection between the element antenna substrate 2 and the radome 5, and an element pattern having no ripple can be obtained.

Since the gain of the array antenna when the beam is scanned depends on the element pattern in the beam direction, the gain change is smooth even when the beam is scanned.

Example 2. FIG. 3 is a diagram showing a configuration of a second embodiment of the present invention, and FIG. 4 is a diagram showing a connection relation of each device of the present invention.

In the figure, 1a is an element antenna excited by linearly polarized waves, and 7 is a grid arranged on a radome 5 parallel to the element antenna substrate 2.

Next, the operation will be described. The signal input to the power feeding circuit 4 is distributed by the power feeding circuit 4 to the number of elements,
After the phase is controlled by each phase shifter 3, it is radiated into space by each element antenna 1.

The radiated electromagnetic wave is incident on the radome 5 and is largely reflected in a direction having a large incident angle. The reflected electromagnetic wave is the element antenna 1 on the front surface of the antenna substrate 2.
It is the same as in the first embodiment that it is absorbed by the radio wave absorber 6 disposed in a portion other than.

On the other hand, from the element antenna 1, an electromagnetic wave of cross polarization orthogonal to the polarization direction of the excited linear polarization is radiated and enters the radome.

On the other hand, a grid 7 is arranged on the radome in a direction orthogonal to the polarization direction of the linearly polarized wave being excited.

FIG. 5 shows a sectional view of the radome 5 in which the grid 7 is arranged. In the figure, W is the grid width and S is the grid spacing.

The transmission coefficient of the electromagnetic wave of the polarized wave parallel to the grid 7 of this grid 7 is obtained by "Equation 2", and the transmission coefficient of the electromagnetic wave of the polarized wave orthogonal to the grid 7 is obtained by "Equation 3".

[0050]

[Equation 2]

[0051]

(Equation 3)

From the "number 2" and the "number 3", the grid 7
By selecting the width W and the spacing S of the grid 7 such that the transmission coefficient of the electromagnetic wave of the polarized wave parallel to the grid becomes small and the transmission coefficient of the electromagnetic wave of the polarized wave orthogonal to the grid 7 becomes large,
The electromagnetic waves of the polarization parallel to the grid 7 are reflected and the grid 7
It can be configured to transmit an electromagnetic wave having a polarization orthogonal to the.

As a result, the cross-polarized waves radiated from the element antenna 1 are reflected by the grid 7 on the radome 5, and are reflected by the electromagnetic wave absorber 6 arranged on the front surface of the antenna substrate 2 other than the element antenna 1 portion. And is absorbed, a radiation pattern with a small cross polarization level is obtained.

Embodiment 3 FIG. FIG. 6 is a diagram showing a configuration of a third embodiment of the present invention, and FIG. 7 is a diagram showing a connection relation of each device of the present invention.

In the figure, numeral 8 is a radome having a curved surface different from that of the element antenna substrate 2.

Next, the operation will be described. The operation until the electromagnetic wave is radiated from each element antenna 1 is the same as that in the first embodiment.

The electromagnetic waves radiated from each element antenna 1 enter the radome 8. However, since the shape of the radome 8 is not a plane parallel to the element antenna substrate 2, the electromagnetic waves radiated from each element antenna have different angles. Then, it enters the radome 8.

The electromagnetic wave incident on the radome 8 is reflected with a reflectance corresponding to each incident angle.

At this time, the electromagnetic wave reflected by the radome 8 is absorbed by the radio wave absorber 6 on the antenna substrate 2.

Since the radio wave absorber 6 cannot completely absorb the electromagnetic wave, the weak electromagnetic wave is emitted again.

At this time, the direction of the electromagnetic wave reflected by the radome 8 differs depending on the position of the element antenna 1, as shown in FIG. In the figure, E1i and E2i are electromagnetic waves emitted from the first and second element antennas 1 through the radome 8, and E1r and E2r are first and second electromagnetic waves.
An electromagnetic wave emitted from the second element antenna 1 and radiated after being multiple-reflected between the radome 8 and the element antenna substrate or the radio wave absorber 6 is shown.

As a result, it is possible to disperse the influence of multiple reflections that affect the respective element antennas, and it is possible to smooth the change in gain during beam scanning when combined as an array antenna.

Further, by improving the shape of the radome 8, it is possible to improve the mechanical strength.

Embodiment 4 FIG. FIG. 9 is a diagram showing the configuration of the fourth embodiment of the present invention.

In the figure, the electromagnetic wave absorber 6 is arranged in the portion excluding the element antenna 1 with the element antenna substrate 2 removed.

The phased array antenna according to this embodiment absorbs the reflected wave from the radome 5 by the arranged wave absorber 6 and the ripple of the element pattern of the element antenna 1 is improved as in the case of the first embodiment. .

The electromagnetic wave radiated from the element antenna 1 is radiated up to a wide angle without being blocked by the electromagnetic wave absorber 6 because the electromagnetic wave absorber 6 is fitted in the element antenna substrate 2.

Example 5. FIG. 10 is a diagram showing the configuration of the fifth embodiment of the present invention.

In the figure, 9 is a resistance film attached on the element antenna substrate 2 except the element antenna 1.
Is a protective layer for protecting the resistance film 9.

Next, the operation will be described. The electromagnetic wave radiated from the element antenna 1 is reflected by the radome 5 as in the first embodiment.

In this embodiment, the resistance film 9 and the protective layer 10 are attached to the portion excluding the element antenna 1.

Here, the quarter-wave absorber is constructed by selecting the sheet resistance of the resistance film 9 and the relative dielectric constant and thickness of the protective layer 10.

FIG. 11 shows a sectional view. In the figure, D1
The thickness and εr1 are the thickness and relative permittivity of the element antenna substrate 2, and D3 and εr3 are the thickness and relative permittivity of the protective layer 10.

At this time, the reflection amount of the incident electromagnetic wave can be obtained by "Equation 4", "Equation 5", "Equation 6", and "Equation 7".

[0075]

(Equation 4)

[0076]

(Equation 5)

[0077]

(Equation 6)

[0078]

(Equation 7)

Here, Zo is the impedance of free space, and Rs is the surface resistance of the resistance film 9.

By determining appropriate parameters from these equations, it is possible to construct a 1/4 wavelength electromagnetic wave absorber that does not reflect incident electromagnetic waves.

Thus, the electromagnetic waves reflected by the radome 5 can be absorbed and the multiple reflections can be removed.

Further, since the resistance film 9 and the protective layer 10 can be made thin, blocking of electromagnetic waves radiated from the element antenna 1 can be prevented and workability is improved.

[0083]

According to the first embodiment of the present invention, since the radio wave absorber is arranged on the front surface of the element antenna substrate except the element antenna, the multiple reflection with the radome is suppressed, and the antenna gain at the time of beam scanning is obtained. And there is an effect that the change can be smoothed.

According to the second embodiment of the present invention, since the electromagnetic wave absorber is arranged on the part of the front surface of the element antenna substrate excluding the element antenna, and the grid for suppressing the cross polarization is arranged on the radome, It is possible to suppress the multiple reflection of, to smooth the antenna gain and change at the time of beam scanning, and to suppress the generation of the cross polarization level.

Further, according to the third embodiment of the present invention, since the radio wave absorber is arranged on the part of the front surface of the element antenna substrate other than the element antenna and the radome shape is a curved surface different from that of the element antenna substrate, It is possible to suppress the multiple reflection of the antenna, further smooth the antenna gain and change during beam scanning, and improve the mechanical strength of the radome.

According to the fourth embodiment of the present invention, since the portion of the front surface of the element antenna substrate excluding the element antenna is removed and the radio wave absorber is arranged in that portion, the multiple reflection with the radome is suppressed and the beam scanning is performed. The antenna gain and change at the time can be smoothed, and the effect of blocking by the electromagnetic wave absorber can be eliminated.

According to the fifth embodiment of the present invention, the resistive film and the protective layer are arranged on the front surface of the element antenna substrate except the element antenna, and the quarter wave absorber is formed together with the element antenna substrate. Therefore, the multiple reflection with the radome can be suppressed, the antenna gain and change at the time of beam scanning can be smoothed, and the effect of blocking by the electromagnetic wave absorber can be eliminated, and the work can be done easily. There is an effect.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a phased array antenna device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a connection relationship according to the first embodiment of the present invention.

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

FIG. 4 is a diagram showing a connection relationship according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a cross section of a radome having a grid.

FIG. 6 is a diagram showing a configuration of a third embodiment of the present invention.

FIG. 7 is a diagram showing a connection relationship according to a third embodiment of the present invention.

FIG. 8 is a diagram showing reflection between an element antenna substrate and a radome in Example 4.

FIG. 9 is a diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a fifth embodiment of the present invention.

FIG. 11 is a diagram showing a cross section of embodiment 5 of the present invention.

FIG. 12 is a diagram showing a connection relationship of a conventional phased array antenna device.

FIG. 13 is a view showing a cross section of a radome.

FIG. 14 is a diagram showing an example of transmission loss and reflection loss depending on an incident angle of a radome.

FIG. 15 is a diagram showing reflection between an element antenna substrate and a radome in a conventional phased array antenna.

FIG. 16 is a diagram showing an example of a radiation pattern of an element antenna in a conventional phased array antenna.

[Explanation of symbols]

1 element antenna, 2 element antenna substrate, 3 phase shifter, 4 feeding circuit, 5 radome, 6 radio wave absorber, 7
Grid, radome with different shape from 8 element antenna substrate, 9 resistance film, 10 protective layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01Q 21/28 H01Q 21/28

Claims (5)

[Claims] 1. An element antenna substrate on which a plurality of element antennas are arranged, a phase shifter connected to the element antenna, a feeding circuit for feeding power to the element antenna, and the element in front of the element antenna substrate. A phased array antenna device comprising a radome arranged in parallel with an antenna substrate and a radio wave absorber arranged on a portion of the element antenna substrate other than the element antenna. 2. An element antenna substrate on which a plurality of element antennas excited by linearly polarized waves are arranged, a phase shifter connected to the element antenna, a feeding circuit for feeding power to the element antenna, Except for the radome, which is arranged in front of the element antenna substrate in parallel with the element antenna substrate and has a grid in a direction orthogonal to the polarization direction of the electromagnetic wave emitted from the element antenna, and the element antenna on the element antenna substrate. A microstrip array antenna device comprising a radio wave absorber arranged in a portion. 3. An element antenna substrate on which a plurality of element antennas are arranged, a phase shifter connected to the element antenna, a feeding circuit for supplying power, and an element antenna substrate arranged in front of the element antenna substrate. A microstrip array antenna device comprising: radomes having different shapes; and a radio wave absorber arranged on a portion of the element antenna substrate other than the element antenna. 4. An element antenna substrate on which a plurality of element antennas are arranged, a phase shifter connected to the element antenna, a feeding circuit for feeding the element antenna, and the element in front of the element antenna substrate. A phased array antenna device in which a radome arranged in parallel with an antenna substrate and the element antenna substrate other than the element antenna on the element antenna substrate are removed, and a radio wave absorber is placed in the removed portion. 5. An element antenna substrate on which a plurality of element antennas are arranged, a phase shifter connected to the element antenna, a feeding circuit for feeding the element antenna, and the element in front of the element antenna substrate. A phased array antenna device comprising: a radome arranged in parallel with an antenna substrate; a resistance film arranged on a portion of the element antenna substrate other than the element antenna; and a protective layer for protecting the resistance film.