JPH02161801A - radome - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radome attached to an antenna or the like.

[Prior art]

Antennas are generally installed outdoors, except in special cases where they are used indoors. Therefore, problems such as deterioration due to wind and rain and adhesion of dust arise.

In particular, in antenna devices whose attitude can be changed freely, for example, antenna devices that are mounted on a moving object such as a car and transmit and receive satellites, the electromechanical components for controlling the antenna attitude may be damaged. Since it is easy to use, dustproof and waterproof measures are required.

Conventionally, a cover called a radome has often been used for this type of need. i.e. the antenna aperture,
Alternatively, the antenna or the entire device is protected by covering the entire antenna device with a dielectric cover.

By the way, since the radome is inserted into the radio wave propagation path, it is desirable that the radio wave transmission loss be as small as possible.For this reason, conventionally, a dielectric plate etc. that is sufficiently thin compared to the wavelength used is used. ing.

[Problem to be solved by the invention]

Conventional radomes using such dielectric thin plates naturally have low physical strength. However, in the past, antennas or antenna devices that required these radomes were mainly installed in fixed buildings or slow moving objects such as ships, so physical strength was not much of an issue. Ta.

However, when attempting to attach an antenna device to a car, train, etc., the wind pressure caused by the movement of the antenna device and changes in the moving environment becomes extremely large, and it is no longer possible to construct a radome without considering its physical strength.

An object of the present invention is to provide a radome with high physical strength and low transmission loss.

[Means to solve the problem]

In order to achieve the above object, the radome of the present invention includes: a first dielectric layer forming an outer shell; a first dielectric layer having a physical strength substantially equal to the physical strength of the first dielectric layer; two dielectric layers; and a third dielectric layer forming a holding layer for maintaining a constant distance between the second dielectric layer and the first dielectric layer; do.

[Effect]

According to this, the first and second dielectric layers, which have substantially the same physical strength, are maintained at a constant interval by the third dielectric layer, so that high physical strength can be obtained. Therefore, the first and second dielectric layers can be made thinner, and the transmission loss of radio waves can be reduced.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

〔Example〕

A preferred embodiment of the present invention can be seen in the antenna device for receiving satellite broadcasting mounted on a mobile object such as an automobile as shown in FIGS. 2a and 2b. In this type of antenna device, since the relative positional relationship with the opposing station (broadcasting satellite) is uncertain, mechanical and electrical measures are taken so that the pointing direction of the antenna can be changed freely.

First, the mechanical configuration will be explained with reference to FIGS. 2a and 2b.

This antenna device detects the arrival direction of radio waves (the direction in which broadcasting satellites are present) and uses four planar antennas 11°, 12°, 13°, and 1° with the same characteristics to receive satellite broadcasting.
4, which are supported in the same plane by an antenna bracket 15 (the main beam of each flat antenna forms the edge of a rectangular cylinder) to form a rectangular antenna unit l.

The antenna bracket 15 is rotatably supported on the rotary table 16 by a shaft 151, and is rotated forward and backward around the shaft 151 by an elevation motor Me. In other words, when the elevation motor Me is energized to rotate normally, the antenna unit 1
The orientation direction in the elevation rotation plane (in the plane perpendicular to the base 17 fixed to the roof of a car, etc.) is the CW force direction (the direction defined in the state shown in Figure 2b: that is, the direction in which the elevation angle increases) When it is updated and reversely energized, it becomes CC
W direction (direction also defined in the state shown in Figure 2b:
(in the direction in which the elevation angle decreases).

This update speed is continuously variable in the range of 0 to 1100 de/s, but the rotation range is 60' (base 17
(within the range of 5° to 65°).

The rotating table 16 is rotatably coupled to a hollow base block 171 fixed to the base 17 via a plurality of sets of angular bearings. This base block 171
A sun gear 172 is integrally formed with the sun gear 172, and a planetary gear (not shown) pivotally connected to the rotary table 6 meshes with the sun gear 172. This planetary gear is an azimuth motor M
It is forward and reversed by a. In other words, when the azimuth motor Ma is energized for forward rotation, the orientation direction within the azimuth rotation plane of the antenna unit 1 (within the center parallel to the base 7) is the direction defined in the CW force direction shown in Figure 2a. 2, that is, the direction in which the vehicle equipped with the device of this embodiment turns to the right), and when reversely energized, the CCW direction (also the direction defined in the state shown in FIG. 2a) (The direction in which the vehicle, etc. on which it is mounted turns left) is updated. This update speed is continuously variable in the range of 1.0 to 100 dF, and there is no limit to the two rotation range.

As mentioned above, the pointing direction of the antenna knee 2 1-1 is
Can be selected arbitrarily depending on the forward/reverse situation of the azimuth motor Ma and/or the elevation motor Me (however,
Technique 1 Novation rotation is base 171: Elevation angle 56 relative to
・Limited to the range of 65″) 9 Next, we will explain the electrical configuration that provides forward and reverse biasing of these azimuth motor Ma and elevation motor Me. 3rd M
Please also refer to

As illustrated in FIG.
The signal received by the antenna 3 is sent to the BS converter 23, the signal received by the planar antenna 14 is sent to the BS converter 24,
Each will be given nine. Each of these BS converters 21
, 22, 23 and 24, the first local oscillator 0 outputs a common first local oscillation (g is mm), and the corresponding planar antennas 11, 12, 13 or 14 are output.
Approximately 1.3GI of the high frequency signal of approximately 12G given by
(Convert to the first intermediate frequency signal of z.

Further, the first intermediate frequency signal outputted by the BS converter 21 is outputted to the tuner 31, and the first intermediate frequency signal outputted by the BS converter 22 is outputted to the tuner 32,
The first intermediate frequency signal outputted by the BS converter 24 is sent to the tuner 33, and the first intermediate frequency signal outputted by the BS converter 24 is sent to the tuner 33.
Power is given to each of the four. Each of these tuners 31
, 32° 33 and 34, using a common second local oscillator signal output by the voltage controlled oscillator vcoc (second local oscillator) in accordance with the control voltage set by the first TSUTARO 4 on the channel of the television set 6, It converts the first intermediate frequency signals of approximately 1 and 3 GHz given by the BS converters 21, 22, 23 or 24 corresponding to
It is converted into a second intermediate frequency signal of MHz.

These second intermediate frequency signals are combined into one in the signal processing circuit 4, and the seventh receiving unit 61 which is applied to the receiving unit 1 of the television set 6 receives this second intermediate frequency signal.
The intermediate frequency signal is demodulated and video and audio are outputted via the CRT display 62 and speakers 63r and 63Q.

By the way, as mentioned above, in the antenna device of this embodiment, each of the BS converters 21, 22, 23 and 24
Using a common first local oscillator number, each tuner 3
1.32 Since a common second intermediate frequency signal is used in 33 and 34, if there is a phase shift between the signals received by each planar antenna, a similar phase shift will occur between the signals received by each planar antenna. Appears between intermediate frequency signals. This phase shift is caused by the arrangement of each planar antenna in the antenna unit 1 and the deviation in the pointing direction of the antenna unit 1 with respect to the direction of arrival of radio waves. Unit 1-
It is possible to know the deviation in the direction of orientation of 1.

In addition to the function of synthesizing each of the second intermediate frequency signals described above, the signal processing circuit 4 detects a phase shift that occurs between each of the second intermediate frequency signals, and detects the phase shift that occurs between each of the second intermediate frequency signals, so that the antenna unit 1 within the azimuth rotation plane
An azimuth error signal indicating the deviation between the pointing direction of the antenna unit 1 and the arrival direction of the radio wave, and an elevation error signal indicating the deviation between the pointing direction of the antenna unit 1 and the arrival direction of the radio wave in the construction/vation rotation plane are generated. It provides the generated azimuth error signal and elevation error signal to the control circuit 5.

The control circuit 5 monitors the limit switches L and IR that detect the limits of the elevation rotation range, and issues instructions to energize the azimuth motor Ma based on the azimuth error signal given from the signal processing circuit 4. is given to the azimuth motor driver D RV a, and an energization instruction for the elevation motor Me based on the elevation error signal is given to the elevation motor driver D RV e, so that the pointing direction of the antenna unit 1 matches the arrival direction of the radio wave. Posture control is performed to make this happen. However, if the antenna unit 1 is shielded and reception becomes impossible, the azimuth gyro Ga and the elevation gyro Go detect the azimuth rotation and the nilevage rotation caused by the external force of the antenna unit 1.

The attitude of the antenna unit 1 immediately before that (the attitude with respect to the direction in which the radio waves arrive) is maintained.

Of the electrical components mentioned above, the BS converter 2
1, 22, 23 and 24 are located on the back of the antenna bracket 15, as shown in Fig. 2a, in order to minimize the parasitic transmission section and prevent external noise picked up during that period from entering the first stage high frequency amplifier. It is installed close to the feeding point of the corresponding planar antenna. For convenience of circuit configuration, tuners 31, 32, 33 and 34. Signal processing circuit 4. First local oscillator LO and voltage controlled oscillator v
The CO is provided on the back side of the antenna bracket 15.

In addition, the azimuth gyro Ga needs to detect the azimuth rotation of the antenna unit 1 due to an external force, so the rotary table 16
Elevation gyro Qe is installed on top of the
It is provided on the back surface of the antenna bracket 15 because it is necessary to detect the elevation rotation of the antenna unit 1 due to external force.

In this way, the antenna unit l, the motors Ma and M
5 Most of the electrical components mentioned above, including e, BS converter 2 (total sign), tuner 3 (total sign), signal processing circuit 4, first local oscillator LO and voltage controlled oscillator The vC○ is mounted above the rotating table 16 (this concept should be understood to include being provided on the antenna bracket 15), and rotates together with the rotating table 16.

Since this rotation is not limited, it is convenient for wiring and the like to provide the control circuit 5 and motor drivers D RV a and DRVe in the same rotation system. For this reason, the second a
As shown in the figure, a control circuit 5 and a motor driver D
RV a and D RV e are installed on a rotating table 16.

Further, a constant voltage power source 72 is also installed on the rotary table 16 for convenience of power supply to each component.

Note that AC 100v is supplied to this constant voltage power supply 72 from a booster circuit 71 that boosts the voltage of the battery Btt.

With the above configuration, the system for controlling the attitude of the antenna unit l is closed on the rotary table 16 (the left side 2 in FIG.
However, since the system that processes the received signal of the antenna unit 1 must be installed inside a car or the like, the television set 6 that is the final output must be installed inside a car or the like. It cannot be closed. Also, regarding the power supply system 7, it is necessary to place the batteries Bt, t and the booster circuit 71 outside the rotary table 16 due to physical rationality. For these systems that go out of the turntable 16, it is necessary to provide rotatable connection means.

The antenna device of this embodiment uses a rotary coupling transformer 8 as a means for transmitting the second intermediate frequency signal from the signal processing circuit 4 to the receiving unit 61 of the television set 6, and uses a set control voltage from the channel selector 64 of the television set 6. A slip ring assembly 9 is provided as a means (2W) for transmitting the voltage to the voltage controlled oscillator vCo and a means (2W) for supplying AC 100v from the booster circuit 71 to the constant voltage power supply 72.6 These will be explained below.

For convenience of explanation, the slip ring assembly 9 will first be described with reference to FIGS. 4a and 4b.

Note that FIG. 4a is a sectional view taken along the line IVA-IVA in FIG. 4b, and FIG. 4b is a sectional view taken along the line I'/B-It/B in FIG. 4a.

The slip ring assembly 9 is attached to the base block 17
It is attached to a hollow pipe 91 inserted and fixed into the hollow part of 1, and consists of a ring part fixed to the pipe 91 and a brush part pivoted to the pipe 91.

The ring portion includes two ring units 92 and 93 and a bottom plate 94. Ring units 92 and 93 are exactly the same, and the former is a ring holder 921. Metal rings 922, 923. and conductor screws 924, 92
5, the latter being a ring holder 931. metal ring 93
2,933. and conductor screws 934 and 935. Hereinafter, for parts with common explanations, the reference numbers of the latter elements are shown in parentheses.

The ring holder 921 (931) is a cylindrical insulator with a convex portion formed in the middle of the circumferential surface, and the metal ring 922 (931)
32) The rice balls 923 (933) are attached to both sides with the convex portion sandwiched therebetween. The conductor screw 924 (934) is inserted from directly below the metal ring 922 (!1132).
25 (935) extend from directly below the metal ring 923 (933) to penetrate through the ring holder 921 (931) 1 in the radial direction.

Each head is directly attached to a metal ring 922 (932
) or 923 (933). However, these conductor screws 924 (934) and 925 (935) are separated by 120@ in the axial projection.

In addition, the ring holder 921 (931) has three screw holes penetrating through it in the axial direction at intervals of 120'.
One of them is conductor screw 924 (934) and conductor screw 925
(935).

These ring units 92 and 93 are assembled with a 120° offset and are screwed onto the bottom plate 94 by screws passing through each screw hole.

The bottom plate 94 has a hole that is concentric with the ring units 92 and 93 and is approximately equal to the outer diameter of the pipe 91.
1 and fixed.

The brush portion includes a brush base 95 and brush units 96 and 97. The brush base 95 is fixed to the rotary table 16'2 so that it does not rotate, so it is pivoted to the pipe 9I via a radial bearing, and on top of it, brush units 96 and 97 having the same configuration are attached to the pipe 91.
It is screwed symmetrically with respect to the center. Hereinafter, for parts with common explanations, the reference numbers of the latter elements are shown in parentheses.

The brush unit 96 (97) is attached to the bracket 961 (9
71), brush holder 962 (972) made of an insulator plate
.

and four completely identical brushes 963 (973) to 96
It consists of 6 (976). Each brush 963 (973) to 96
6 (976) is an arc-shaped elastic metal with shoes at both ends, arranged on the brush holder 962 (972) at the same intervals as the intervals between the metal rings of the ring part, and the central part is It is fixed by conductor screws passing through the two brush holders 962 (972). In addition, the brush holder 9
62 (972) is attached to a position where the two shoes of each brush are pressed against the corresponding metal ring with a predetermined pressure by the bracket 961 (971). In other words, the metal ring 922 has four
metal ring 923 has four shoes attached to brushes 964 and 974, metal ring 932 has four shoes attached to brushes 965 and 975,
Four shoes provided on brushes 966 and 976 come into contact with metal ring 933, respectively. Therefore, the four conductor screws that attach the paired brushes are each short-circuited to reduce the contact resistance between one metal ring and the two brushes that are in contact with it.

The ring portion and brush portion described above are covered by a cover 98. This cover 98 is a cylinder with a bottom plate, and the bottom part of the cover 98 is rotatably penetrated by the pipe 91, and the opening part is fixed to the brush base 95.6 Also, inside the bottom part, there is a ring-shaped terminal plate 99. is equipped with four terminals 991 to 994 that pass through the bottom and the terminal plate 99.
It has. These terminals 991 to 994 connect metal rings 922 to 933 and brushes 963 (9
73) to 966 (976), or the set control voltage from the channel selector 64, to the voltage controlled oscillator vCO.
Alternatively, it is distributed to the booster circuit 71.

On the other hand, the rotary coupling transformer 8 includes a pair of coil plates 81 supported in parallel above the slip ring assembly 9.
and 82 (see Figure 2b).

As is clear from FIGS. 1a and 1b, these coil plates 81 and 82 have exactly the same configuration, and include a rectangular substrate 811 (821), an L-turn circular coil/L/
812 (822), positioning memo-jy813 (823
), 50G (7) coaxial connector 814 (824)
, and an attenuator 815 (825).

The substrate 811 (821) is made of a translucent glass epoxy plate, and the circular coil 812 (822) is formed on its surface by etching copper foil. Further, the positioning mark 813 (823) is printed on the inside of the circular coil 812 (822), and consists of a number of concentric circles concentric with the circular coil 812 (822) and two orthogonal straight lines passing through the center thereof.

The coaxial connector 814 (824) is connected to the board 811 (821).
), one end of a circular coil 812 (822) is connected to its inner conductor, and the other end of the circular coil 812 (822) is connected to its outer conductor. These connectors include a coaxial cable (not shown) connected to the signal processing circuit 4 or a coaxial cable 85 (fourth
Figure a) is connected.

The attenuator 815 (825) is a resistor for widening the band, and is inserted between both terminals of the circular coil 812 (822).

These coil plates 81 and 82 are arranged above the slip ring assembly 9 so that their surfaces are parallel and facing each other, and the circular coils 812 and 822 are coaxially rotatable relative to each other. mounted on. That is, the former is attached to a stay 83 fixed to a cover 98, and the latter is attached to a stay 84 fixed to a pipe 91. In this installation, each coil plate 81.82 is easily supported in parallel with the mounting portion of each stay 83.84 facing up, and positioning marks 813.822 are printed on the rotation of each circular coil 13], 2.822. It is easy to align the shafts by looking through them from the axial direction.

In the rotary coupling transformer 8 configured in this way,
One-turn circular coil 81 of the same diameter spaced parallel on the same axis
2 (822) rotate relative to each other, microscopic non-uniformity of each coil and distortions such as spacing are averaged over the entire circumference of each coil, and the periodic noise caused by this is averaged out. It will be understood that there is no generation, and furthermore, since there is magnetic coupling between these coils, transmission of common noise is blocked.

In addition, each coil plate is extremely easy to create, and
Since they are the same, they can be made in the same process, which is very advantageous in terms of cost.

By the way, when this type of antenna device is installed in a car or the like, the outside of the car, for example, the roof, is selected as the mounting location. Therefore, it is necessary to protect the device from dust, wind and rain. Radome RDM plays this role. In this case, since the front surface of the antenna will be covered with a dielectric material, it is desirable to suppress the transmission loss due to this radome RDM as small as possible. In other words, the radome RDM should be made of as thin a material as possible, but due to the characteristics of this type of antenna device, it is impossible to avoid vibrations and wind pressure caused by the movement of the automobile to which it is attached, so the strength should not be neglected. I can't.

Therefore, in this embodiment, the radome RDM is configured as described below.

The exact cross-sectional shape of the radome RDM is shown in Figure 1a.
Figure b shows its configuration. This radome RDM has a rotationally symmetrical shape and is approximately 1fflI! It consists of an outer shell a made of FRP with a thickness of 1, an inner shell made of FRP with a thickness of about 11, and a core made of polystyrene foam with a thickness of about 4 mm+ sandwiched between them.

Here, eboshiki type FRP having a dielectric constant of about 4 and a loss of about 0.02 is used for the outer shell a and the inner shell. In other words, although the dielectric constant is relatively high, by making it sufficiently thin, the transmission loss of radio waves can be kept low, as shown in FIG. 1c. In addition, the strength deteriorated by making it thinner,
This is compensated for by sandwiching a polystyrene foam core with a low dielectric constant, resulting in a radome with low transmission loss and high strength.

Incidentally, when the radome RDM shown in Fig. 1a is installed without the radome installed, the 3 mm thick FR
When a radome made of P (outer shell a and inner shell are made of the same material) is attached, and when a radome made of 2 mm thick FRP (outer shell a and
, the relationship between the received level (absolute level) and the frequency (measured at the output side of the signal processing circuit 4) is shown in Figures 1d and 1d, respectively. It is shown in Figure 1e, Figure 1f and Figure 1g. As can be seen from these graphs, there is almost no transmission loss when the radome ROM of this example is installed, whereas there is a transmission loss of 3 to 5 dB when the radome made of FRP with a thickness of 3n+m is installed. There is a thickness of 2mm
When installing a radome made of FRP, not only does the transmission loss become even larger, but the frequency characteristics also change.

The relation between the reception level and the frequency of the reception power and the reception power after the transmission loss is <1iilJ constant condition is the above ( , this 1
．． II) 4.

4'2, ], uni The whole antenna device is kl/-F
- M RII) By covering from M tlm, the temperature If1 in Rad-7, RDM may become -: I-1. Prevent this 11. 1, −, base 1′
The chamber is equipped with a cooling fan driven by a motor M (see FIG. 3) which receives power supply from the pressure circuit 71.

〔Effect of the invention〕

As explained above, the dome according to the present invention has a first dielectric layer forming an outer shell; having a physical strength substantially equal to the physical strength of the first dielectric layer and forming an inner shell. a second dielectric layer; and a third dielectric layer forming a holding layer for maintaining a constant distance between the second dielectric layer and the first dielectric layer; Therefore, high physical strength can be obtained. Therefore, the first and second dielectric layers are made thinner. 2 and 4 can be achieved, and the transmission loss of radio waves can be reduced to 4.

[Brief explanation of the drawing]

FIG. 1a is a sectional view showing the cross-sectional shape of the dome RDH4 according to an embodiment of the present invention, and FIG. It is a partially enlarged view of -zo-. FIG. 1c is a graph showing the transmission loss depending on the thickness of FRP used in the 1-two dome ROM 1 knee of the embodiment. Figure 1d shows the relationship between the reception level and frequency when the dome is not attached. Figure 1e shows the relationship between the reception level and frequency when the radome RDM shown in Figure 1a is attached. Figure 1f shows the relationship between the reception level and frequency when the radome RDM shown in Figure 1a is attached. is 3I thick! The relationship between the reception level and frequency when a radome made of FRP of [lIl] is attached is as follows.
Figure 1g shows the relationship between the reception level and frequency when a radome made of FRI with a thickness of 2 mm is installed, and Figure 1h shows the relationship between the reception level and frequency when the transmission loss is increased until reception becomes impossible. This is a graph showing each relationship. Fig. 2a is a plan view showing the mechanical configuration of a satellite transmitting/receiving (1m) antenna device in which the radome ROM of the embodiment is used, and Fig. 2b is a front view thereof. FIG. 4a is a block diagram showing the electrical configuration of the antenna device shown in FIG. 2b.
FIG. 41 is a vertical sectional view showing the structure of the slip ring assembly 9 used in the antenna device shown in FIGS. 5a and 5b are plan views showing the configuration of the coil plate 81 or 82 constituting the rotary coupling lance used in the antenna device shown in FIGS. 2a and 21). 1: Antenna unit, Tsu 1- 11-14: Plane-/end 15: Antenna bracket 1G = Rotating table 17: Base 2: BS converter: 3: Tuner 4: Signal processing circuit 5 : Control circuit 6: Television set 61: Receiving unit 63 Nisby cuff: Power supply 7H Boost circuit 8: Rotating coupling 1-Lance 81.82: Coil plate 811.821: Board 812.8228 Circular coil 813.823: Positioning mark 814.824: Coaxial connector 81.5, 825: Attenuator 83.84 Nisty 85: Coaxial cable 9 Nislip ring assembly 91: Pipe 92.93: Ring unit 1- 921.931: Ring holder 922.923, 932, 933: Metal ring 924
．． 925,934,935: Weekly holiday screw 72: Constant voltage power supply 62: CRT display 94: Bottoming 95; Brush base 96.97: Brush unit 961.971 Bracket 962.972: Brush holder 963-966.973-976: Brush 98: Cover 99: Terminal plates 991 to 994: Terminal RDM Elm dome a: Outer shell (first dielectric layer) b: Inner shell (second dielectric layer) C: Core (third dielectric layer) Ha , Me: Motor DRVa, DRVe: Motor driver Ga, Ge: Gyro

Claims (2)

[Claims] (1) a first dielectric layer forming an outer shell; a second dielectric layer having a physical strength substantially equal to the physical strength of the first dielectric layer and forming an inner shell; and the second dielectric layer. A radome comprising: a third dielectric layer forming a holding layer for maintaining a constant spacing between the dielectric layer and the first dielectric layer. (2) The dielectric constant of the third dielectric layer is lower than both the dielectric constant of the first dielectric layer and the dielectric constant of the second dielectric layer. ) radome as described in section.