JPH11220317A - Loop antenna - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the size of a loop antenna and reduce the number of parts and the number of assembly steps. An upper surface of a double-sided printed wiring board (15) is a ground plane (15a), an RF circuit (15b) is provided on the back surface, and a loop element (12) is provided above the ground plane (15a).
Are arranged in parallel. A power supply conductor 13 is arranged between the loop element 12 and the ground plane 15a, and the power supply conductor is connected to the RF circuit on the back surface of the wiring board to supply power from the power supply conductor to the loop element by electromagnetic coupling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loop antenna, and more particularly, to a loop antenna that is reduced in size and facilitates assembly.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIG. FIG. 6 shows a linearly polarized loop antenna 1. Both ends of a square loop element 2 are connected to a balanced line connection terminal of a balanced / unbalanced conversion and impedance conversion circuit 4 through a balanced feed line 3, and the other unbalanced line. A coaxial cable 5 connects the connection terminal and an RF circuit (not shown) for reception or transmission.
Connect by. As shown in the figure, when a feed point is provided on the horizontal element of the loop element 2, the antenna becomes a horizontally polarized antenna. When the feed point is positioned on the vertical element by rotating the feed point by 90 ° from the posture of FIG. It becomes a wave antenna.

Although not shown, if a perturbation element is provided in the loop element 2, a circularly polarized loop antenna is obtained.

[0004]

The loop antenna 1 shown in FIG. 6 requires a balanced / unbalanced conversion and impedance conversion circuit 4, so that the number of parts and the number of assembling steps are large.
There is a disadvantage that the cost is high. Therefore, there arises a technical problem to be solved in order to reduce the number of parts and the number of assembling steps and to reduce the size of the loop antenna, and an object of the present invention is to solve the above problem.

[0005]

SUMMARY OF THE INVENTION The present invention proposes to achieve the above object, in which an RF circuit is provided on one surface of a circuit board, a back surface is a ground plane, and a loop element is provided on the circuit board. And the power supply conductor is disposed in parallel with the ground plane of the loop element, and the power supply conductor is disposed in parallel between the loop element and the ground plane and along the loop of the loop element. An object of the present invention is to provide a loop antenna connected to a circuit and feeding power from a feed conductor to a loop element by electromagnetic coupling.

Further, first and second power supply conductors whose power supply points are at 90 ° intervals when viewed from the center of the loop are arranged between the loop element and the ground plane and in parallel along the loop of the loop element. Then, the first and second power supply conductors are connected to the antenna switching circuit of the RF circuit through through holes provided in the circuit board, and power is supplied from the power supply conductor to the loop element by electromagnetic coupling, and horizontal and vertical polarizations are converted. A loop antenna configured to selectively transmit and receive, and a perturbation element positioned equidistant from the first and second feeding points in the loop element to select between left-handed circular polarization and right-handed circular polarization. It is intended to provide a loop antenna configured so as to be able to perform transmission and reception.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a right-handed circularly polarized wave loop antenna 11 as an example of the loop antenna according to the first embodiment, a square loop element 12 having a perimeter of C (about one wavelength), an L-shaped feed conductor 13 having a length LV + LH, and Perturbation element portions 14a, 14 having an element length ΔL provided for generating circularly polarized waves
4b and a double-sided printed wiring board 15 having a larger area than the loop element 12.

The entire surface (upper surface in the figure) of the double-sided printed wiring board 15 is a ground plane 15a, and electronic components are mounted on an RF circuit wiring pattern 15b formed on the rear surface to constitute an RF circuit. Ground plane 1
Above 5a, the loop element 12 is arranged in parallel with the ground plane 15a, and the power supply conductor 13 is arranged between the loop element 12 and the ground plane 15a. The power supply conductor 13 penetrates through the through-hole 16 which is a non-through hole provided in the double-sided printed wiring board 15 to the back surface, and is connected to the RF circuit 15b on the back surface.

Here, the height of the loop element 12 from the ground plane 15a is h, and C = 1.032λ.
_1.472 , ΔL = 0.029λ _1.472 , LV = 0.014
_{λ 1.472, LH = 0.236λ 1.472,} h = 0.049
_1λ is _1.472 . However, λ _{1.47 2,} the design frequency 1.
Free space wavelength at 472 GHz.

The loop element 12 is supplied with power by electromagnetic coupling from the feed conductor 13 and circularly polarized waves are synthesized by the perturbation element sections 14a and 14b. As shown in the figure, the loop element 12 is viewed from the front of the antenna (from above in FIG. 1). When the perturbation element section is arranged at a position of about +45 degrees or about -135 degrees from the feeding point, right-hand circularly polarized light is emitted.

Although not shown, the perturbation element 14
By rotating the positions of a and 14b by 180 ° and reversing the extension direction of the feed conductor 13 from side to side, a loop antenna for left-hand circular polarization is obtained. Further, the loop element 12 to the perturbation element section 14
If a and 14b are removed, a loop antenna for linear polarization corresponding to horizontal polarization or vertical polarization is obtained.

As described above, the double-sided circuit board 15 provided with the ground plane 15a and the RF circuit pattern 15b is disposed so as to face the closed loop element 12, and power is supplied from the power supply conductor 13 to the loop element 12 by electromagnetic coupling. , Low profile and small size, and easy to assemble.

FIG. 2 is a structural explanatory view of the loop antenna 21 for linear polarization according to the second aspect. A double-sided printed wiring board 23 facing the loop element 22 is provided at an intermediate point of the horizontal element 22H of the loop element 22. Immediately below and the vertical element 22
A through-hole 2 which is a non-through-hole immediately below the middle point of V
4 and 25 are provided, and the ends of the two power supply conductors 26 and 27 pass through the through holes 24 and 25 and are connected to the ground plane 2.
3a is connected to the RF circuit 23b on the back surface.

The through hole 2 facing the horizontal element 22H
The power supply conductor 26 rising vertically from 4 refracts at a right angle to the left as viewed from the upper surface, extends parallel to the horizontal element 22H and the left vertical element 22V, and reaches an intermediate point between the left vertical element 22V. In addition, the power supply conductor 27 which rises vertically from the through hole 25 facing the right vertical element 22V is bent upward at a right angle and extends in parallel with the vertical element 22V and the upper horizontal element 22H. Has reached.

The power supply conductors 26 and 27 are connected to a switching circuit of the RF circuit, and supply power from the power supply conductors 26 or 27 to the loop element 22 by electromagnetic coupling. When power is supplied from the horizontal power supply conductor 26, horizontal polarization is radiated from the loop element 22, and when power is supplied from the vertical power supply conductor 27, vertical polarization is radiated. By switching the horizontal power supply conductor 26 and the vertical power supply conductor 27, one Can receive or transmit the horizontal polarization and the vertical polarization.

FIG. 3 shows a loop antenna 31 for left-handed or right-handed circularly polarized waves according to the third aspect of the present invention.
This is the same as the loop element 12 shown in FIG. As shown in the figure, the perturbation element portions 33a, 33
3b is located at + 45 ° and −135 ° from the power supply conductor 35 provided on the double-sided printed wiring board 34, and the other power supply conductor 3
6 are located at −45 ° and + 135 °.

When power is supplied from the horizontal power supply conductor 35, the + Z signal is output from the loop element 32 similarly to the loop antenna 11 in FIG. 1 due to the reactance of the perturbation element sections 33a and 33b.
A right-handed circularly polarized wave is emitted in the direction. In addition, the vertical power supply conductor 3
When power is supplied from 6, the loop element 32 emits left-handed circularly polarized waves in the + Z direction. Therefore, the horizontal power supply conductor 3
5 and the vertical feed conductor 36, the left and right circularly polarized waves can be transmitted and received by one loop antenna 31.

FIG. 4 shows another embodiment. The basic configuration is the same as that of the loop antenna of FIG. 3, but the loop element 42 of the circularly polarized loop antenna 41 is formed of a metal plate instead of a wire. And has a constant width in the radial direction. 42a and 42b are loop elements 42.
This is a perturbation element section provided in.

The plate-shaped loop element 42 has a larger difference between the inner circumference and the outer circumference than the loop element made of a wire, and has an intermediate wavelength between the inner circumference and the outer circumference of about one wavelength. It is enlarged. Also, the power supply conductors 43 and 44 have a flat plate shape formed of a metal plate similarly to the loop element 42, and the resonance bandwidth is expanded similarly to the loop element 42.

As shown in FIG. 5, tenon portions 43a and 44a are formed at circuit connection side ends of the power supply conductors 43 and 44, respectively.
The shape of the through holes 46 and 47 of the double-sided printed wiring board 45 is a square shape into which the tenon portions 43a and 44a fit. Therefore, if the tenon portions 43a and 44a are inserted into the through holes 46 and 47, the positioning of the power supply conductors 43 and 44 on the XY plane is performed, and the RF circuit pattern provided on the back surface of the ground pattern 45a of the double-sided printed wiring board 45 is provided. By soldering the mortise portions 45a and the tenon portions 43a and 44a,
4 is set in a predetermined direction along the loop of the loop element 42.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible within the technical scope of the present invention, and it goes without saying that the present invention extends to those modifications. is there.

[0022]

As described above, the loop antenna of the present invention supplies power to the loop element from the feed conductor by electromagnetic coupling, so that the number of parts and the number of assembly steps are smaller than those of the conventional loop antenna, and the ground plane is also reduced. By providing the RF circuit on the back surface of the device, it can be formed extremely small.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a loop antenna according to claim 1.

FIG. 2 is an explanatory view showing a loop antenna according to claim 2;

FIG. 3 is an explanatory view showing a loop antenna according to claim 3;

FIG. 4 shows another embodiment of the loop antenna, wherein (a)
Is a front view of the loop antenna, and (b) is a side view.

5A and 5B show a connection portion between the power supply conductor and the double-sided circuit board shown in FIG. 4, wherein FIG. 5A is a partial cross-sectional view, and FIG.
FIG. 4 is a cross-sectional view taken along line -A.

FIG. 6 shows a conventional example and is a front view of a loop antenna for linear polarization.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Loop antenna for circular polarization 12 Loop element 13 Feeding conductor 14a, 14b Perturbation element part 15 Double-sided printed wiring board 15a Ground plane 15b RF circuit pattern 16 Through hole 21 Linear loop antenna for linear polarization 22 Loop element 23 Double-sided printed wiring board 24 , 25 Through-holes 26, 27 Feed conductor 31 Circular polarization loop antenna 32 Loop element 33a, 33b Perturbation element 34 Double-sided printed wiring board 35, 36 Feed conductor

Claims (3)

[Claims] An RF circuit is disposed on one surface of a circuit board, a back surface is a ground plane, a loop element is disposed in parallel with the ground plane of the circuit board, and a power supply conductor is connected to the loop element and the ground plane. And a power supply conductor connected to the RF circuit through a through hole provided in the circuit board, and power is supplied from the power supply conductor to the loop element by electromagnetic coupling. 2. An RF circuit is provided on one surface of a circuit board, a back surface is used as a ground plane, and a loop element is arranged in parallel to the ground plane of the circuit board so that a feeding point is 90% when viewed from the center of the loop. The first and second power supply conductors having an interval of ° are arranged in parallel between the loop element and the ground plane and along the loop of the loop element, and the first and second power supply conductors are provided through through holes provided in the circuit board. A loop antenna configured to connect the power supply conductor to an antenna switching circuit of an RF circuit, and to selectively transmit and receive horizontal polarization and vertical polarization by supplying power to the loop element from the power supply conductor by electromagnetic coupling. 3. An RF circuit is provided on one surface of a circuit board, a back surface is used as a ground plane, and a loop element is arranged in parallel to the ground plane of the circuit board so that a feeding point is 90% when viewed from the center of the loop. The first and second power supply conductors having an interval of ° are arranged in parallel between the loop element and the ground plane and along the loop of the loop element, and the first and second power supply conductors are provided through through holes provided in the circuit board. Is connected to the antenna switching circuit of the RF circuit, and a perturbation element is provided in the loop element at an equal distance from the first and second feeding points. A loop antenna configured to selectively transmit and receive circularly polarized waves and right-handed circularly polarized waves.