JPH04122101A - Plane antenna - Google Patents

Abstract

PURPOSE:To reduce transmitted power by selecting each electric length from other supply terminal to a one antenna array and from one supply terminal to other antenna array so that a signal propagating through the electric length from other supply terminal to one antenna array is in phase to a signal propagating through the electric length from one supply terminal to one antenna array and a signal propagating through the electric length from other supply terminal to other antenna array is in opposite to a signal propagating through the electric length from one supply terminal to other antenna array. CONSTITUTION:An electric length of a feeder from one supply terminal 27 on a sub circuit board 2 to one antenna array 33 or 35 of a main circuit board 1 is selected to be different from an electric length of the feeder from one supply terminal 27 on the sub circuit board 2 to other antenna array 34 or 36 of the main circuit board 1 by 1/4lambdag (lambdag is a line wavelength) so that a signal propagating through the electric length from the other supply terminal 28 to the one antenna array 33 or 35 is in-phase to a signal propagating through the electric length from the one supply terminal 27 to the one antenna array 33 or 35, and a signal propagating through the electric length from the other supply terminal 28 to the other antenna array 34 or 36 is in opposite phase to a signal propagating through the electric length from the one supply terminal 27 to the other antenna array 34 or 36. A signal received by the antenna array 33 appears at the terminal 27 without no phase lag but a signal received by the antenna array 34 appears at the terminal 27 with a phase lag of 180 deg. with respect to the phase of the signal received by the antenna array 33 and the signals are just canceled when they are synthesized and no output appears at the terminal 27. Thus, the loss of the transmitted power is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a beam switching type planar antenna used in a vehicle sensor using microwaves.

(b) Conventional technology As shown in the "Multi-lane Vehicle Detector" submitted by one of the applicants, multiple a distributor which has a receiving element and distributes the received signal obtained to each element according to the number of lanes, and a distributor which distributes the received signal obtained to each element according to the number of lanes, and a distributor which has a predetermined number of receiving elements, respectively, so that the distributed signal can be handed over according to the number of lanes. An antenna is known that is equipped with a plurality of phase shifters that delay the phase by the phase of each lane, and simultaneously obtains a received signal for each lane with a directional characteristic corresponding to each lane.

(c) Problems to be Solved by the Invention It has been found that in this conventional antenna, the power transmitted is small in inverse proportion to the number of distributions of the distributor.

In other words, the transmitted power is reduced to 1/2 in the case of a two-way divider, and 1/3 in the case of a two-way divider.

SUMMARY OF THE INVENTION An object of the present invention is to provide a beam switching type planar antenna with little loss of transmitted power.

(d) Means for Solving the Problems The planar antenna of the present invention is shown in FIGS. 1(a) and 1(b).
As shown in the figure, an antenna is constructed by connecting in series a grounding conductor 3, a dielectric layer 4 provided on the surface of this grounding conductor 3, and two or more patch-like radiating elements 5 formed on the surface of this dielectric layer 4. A main circuit board l in which a plurality of arrays 33,..., 36 and supply terminals 19,... 22 for supplying power to the antenna arrays are arranged; FIG. 1(C), FIG. 1(b) As shown in FIG.
A dielectric layer 7 provided on the surface of this ground conductor 6, two supply terminals 27 and 28 formed on the surface of this dielectric layer 7 for supplying power, and connections to each of these supply terminals 27 and 28. are connected to the distributors 23 and 24, and the phase of only the power supplied from the other distributor 24 is changed by 90° without changing the phase of the power supplied from one distributor 23. The phase of only the power supplied from the output terminal 10 or 12 and the distributor 23 of one of them is changed to 90
As shown in FIG. 1 (G), a sub-circuit board 2 is provided with a hybrid circuit 25 or 26 having an output terminal 11 or 13 that does not change the phase of the power supplied from the other distributor 24; , a transmission line 1 connecting the output from the sub circuit board 2 to the antenna array of the main circuit board 1;
4, from the one supply terminal 27 on the sub circuit board 2 to the main circuit board 1 shown in FIGS. 1(a), . . . , FIG. 1(C)
The electrical length of the feed line from one antenna row 33 or 35 to the other adjacent antenna row 34 or 36 differs by 1/4λg (λg: line wavelength), and the same antenna from the other supply terminal 28 The electrical length up to the column is such that one antenna column 33 or 35 has the one supply terminal 27
It is characterized in that it is provided so that it is in phase with the signal from the antenna array 34 or 36, and in opposite phase to the other antenna array 34 or 36.

The patch-shaped radiating element 5 used in the present invention can be made of any conductor, and one that has low loss and is easy to form is selected and used.

The antenna rows 33, . . . , 36 in which two or more such radiating elements are connected in series can be connected by a conventionally known feed line 8. As with the radiating element, any material can be used for the feed line 8 as long as it is a conductor, and is appropriately selected and used. As supply terminals 19, . . . , 22 for supplying power to the antenna array,
The main circuit board 1, which is similar to the radiating element 5 and the feed line 8, and has a plurality of them arranged, is supported by a dielectric layer 4, as shown in FIG. It is supported by a ground conductor 3.

This dielectric layer 4 can be made of materials with low relative permittivity and dielectric loss tangent, such as polyethylene, polyimide, polyester, polyfluoroethylene, polypropylene, polyetherimide, polyether ether ketone, etc., or ordinary epoxy It is also possible to use resins such as acrylic or acrylic resins that contain many bubbles, or porous inorganic insulating materials. Furthermore, a film made of the above-described organic insulating material can be used to support the main circuit, these insulating materials can be used as a spacer, and the air layer can be used in place of the dielectric.

The material of the ground conductor 3 used in the planar antenna of the present invention may be any conductor, such as copper, aluminum, iron, bronze, brass, etc., depending on the required electrical conductivity and mechanical strength. The thickness and material can be selected depending on the required characteristics.

Supply terminals 27 and 28 that supply power with two different phases, and distributors 23 and 2 connected to the supply terminals.
4, and an output terminal 10 or 12 that is connected to the distributor and changes the phase of only the power supplied from the other distributor 24 by 90@ without changing the phase of the power supplied from one distributor 23, and a hybrid circuit 25 or 26 having an output terminal 11 or 13 that changes the phase of only the power supplied from the one distributor 23 by 90 degrees and does not change the phase of the power supplied from the other distributor 24. Circuit board 2 also
It can be made in the same manner as the main circuit board 1 described above.

This high printed circuit 25 or 26 is specifically
It has the shape shown in the figure, and the power supplied from the line 29 is taken out to the line 31 on the same line without changing the phase, and the electric power is output to the line 32 on the diagonal with a 90° phase delay. Also, the power supplied from the line 30 is taken out to the line 32 on the same line without changing the phase, and is taken out to the line 31 on the diagonal with a 90' phase delay. be.

Further, as shown in FIG. 1(b), the sub-circuit board 2 is supported by a dielectric layer 7, and the dielectric layer 7 is supported by a ground conductor 6.

This dielectric layer 7 is made in the same manner as the dielectric layer 4, and the ground conductor 6 is also made in the same manner as the ground conductor 3.

As the transmission line 14 for connecting the output from the sub-circuit board 2 to the antenna row of the main circuit board 1, a coaxial cable or a connector having a coaxial structure can be used, and preferably one with low transmission loss is used.

The electrical length of the feed line from the one supply terminal 27 on the main circuit board 2 to the one antenna row 33 or 35 on the main circuit board 1 is between the other adjacent antenna row 34 or 36. In order to make the difference by 1/4λg, the hybrid circuit 25 or 26 is used.

Further, the electrical length from the other supply terminal 28 to the same antenna row 33 or 35 is in phase with the signal from the one supply terminal 27, and in opposite phase to the other antenna row 34 or 36. In order to provide a hybrid circuit 25 or 2 from each supply terminal 27 and 28,
6 to equal electrical length, and hybrid circuit 2
This can be realized by making the electrical lengths from 5 and 26 to each antenna row 33, . . . 36 equal.

(E) Effect With this configuration, as shown in FIG. The hybrid circuit 25 outputs the signal to the terminal 27 without any phase delay, and at the same time, the hybrid circuit 25 outputs the signal to the terminal 28 with a 90" phase delay. At this time, the radio waves received by the antenna array 34 are The signal is calculated from the interval l and the incident angle of the radio wave -θ!・The signal is delayed in phase from the signal at the antenna array 33 by sinθ.The phase of this f-sinθ is λg/4 at that frequency, that is, 90 In the case corresponding to @, a signal is sent from the hybrid circuit 25 to the terminal 28 via the terminal 11 with a delay of 90 degrees from the signal of the antenna array 33, and a signal sent to the terminal 27 is delayed further by 90 degrees and delayed by 180 degrees. .

Therefore, the terminal 28 has a 90"
When the delayed signal and the antenna array 34 are combined, a signal delayed by 90 degrees with respect to the antenna array 33 appears, and when combined, a large signal with a phase delay of 90 degrees of the signal received by the antenna array 33 appears. However, the antenna row 33 is connected to the terminal 27.
The signals received from the antenna array 34 appear with no phase delay, but the signals from the antenna array 34 have a phase delay of 18 degrees with respect to the antenna array 33, and when combined, they are just erased.
No output appears at terminal 27.

The outputs of antenna arrays 35 and 36 operate in a similar manner.

Conversely, when the incident angle of the radio wave is θ, a signal appears at the terminal 27 and no signal appears at the terminal 28.

In this way, the antenna can form beams with very low losses of equal magnitude in two directions, and it is possible to choose which one to use.

(F) Embodiment FIGS. 1(a), . . . , and FIG. 1(C) show a planar antenna according to an embodiment of the present invention.

Dielectric layers 4 and 7 were made of foamed polyethylene, and ground conductors 3 and 6 were made of aluminum plates. The main circuit board work and the sub circuit board 2 were connected in a coaxial structure.

At this time, when I measured using the antenna for reception, I found that
The loss of output to each terminal 27 and 28 is 0.5 to 1 d
B, and it was possible to create a beam switching type antenna with extremely low loss.

(G) Effects of the Invention As explained above, the present invention makes it possible to provide a beam switching type planar antenna with extremely low loss.

[Brief explanation of the drawing]

FIG. 1(a) is a top view showing a planar antenna according to an embodiment of the present invention, and FIG. 1(b) is a side view of the same embodiment.
FIG. 1(C) is a perspective bottom view of the planar antenna of the same embodiment, the back view of FIG. 1(a), FIG. 2 is a top view of the hybrid circuit used in the planar antenna of the same embodiment, and FIG. 1 is a conceptual diagram used to explain the present invention in detail. Explanation of symbols 1: Main circuit board, 2: Sub-circuit board, 3 and 6: Ground conductor, 4 and 7: Dielectric layer, 10,...
, 13: Connection terminals on the beam switching circuit board, 19,..., 22 Connection terminals on the antenna circuit board, 2
5.26: Hybrid circuit, 33,..., 36: Antenna row. Patent applicant: OMRON Corporation (1 idiot)

Claims (1)

[Claims] (1) A ground conductor, a dielectric layer provided on the surface of this ground conductor, and an antenna row in which two or more patch-like radiating elements formed on the surface of this dielectric layer are connected in series, and power is supplied to this antenna row. a main circuit board in which a plurality of supply terminals are arranged, a ground conductor, a dielectric layer provided on the surface of the ground conductor,
Two power supply terminals formed on the surface of this dielectric layer, a distributor connected to each of these supply terminals, and a phase of the power supplied from one of the distributors connected to this distributor. An output terminal that changes the phase of only the power supplied from the other distributor by 90 degrees without changing the output terminal, and an output terminal that changes the phase of only the power supplied from the one distributor by 90 degrees without changing the phase of the power supplied from the other distributor. a sub-circuit board having a hybrid circuit having an output terminal that does not change; and a transmission line connecting an output from the sub-circuit board to an antenna array of the main circuit board; The electrical length of the feed line from the one supply terminal to one antenna row of the main circuit board differs by 1/4λg (λg: line wavelength) between the other adjacent antenna rows, and 1. A planar antenna, characterized in that the electrical length up to the antenna array is provided such that one antenna array has the same phase as the signal from the one supply terminal, and the other antenna array has the opposite phase.