JPH08293725A - Omnidirectional loop antenna and receiver using the same - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] A small loop antenna that can be installed in a vehicle to receive a radio wave signal entering from all directions with high sensitivity. First and second loops (10a, 10b) each standing upright at 90 ° to a horizontal plane and orthogonal to each other
And a third loop 10c formed horizontally so as to be orthogonal to both loops, and conductor wires 30a, 30b, 30c wound around the concave groove portions of the outer peripheral surfaces of the first to third loops in all directions. A loop antenna. This antenna, three impedance matching circuits 40 each composed of an inductor and a capacitor and attached to the inner peripheral surfaces of the first to third loops, and a power combiner 6 for combining the powers of received signals.
0, three coaxial cables 50 interposed between the three impedance matching circuits and the power combiner to determine the phase shift, and the power combiner output signal is amplified using the microstrip amplifier technique. And a low noise wide band amplifier 70 for configuring a receiving device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loop antenna having omnidirectionality, that is, an omnidirectional loop antenna, and a receiver using the same. More specifically, a small omnidirectional device installed in a vehicle and capable of receiving both vertically polarized signals such as AM and FM radio broadcast signals and horizontally polarized signals such as television broadcast signals in any direction. The present invention relates to a loop antenna and a receiver using the loop antenna.

[0002]

2. Description of the Related Art A conventional example of a loop antenna is shown in FIG.
The loop antenna of FIG. 1 is Korean Patent Application No. 92-1.
No. 2494, a large number of concave groove portions are formed on the outer peripheral surface of each of the cylindrical first loop 1a and the second loop 1b.
The conductor wires 3a and 3b are wound a fixed number of times around the concave groove portions a and 1b. The radio wave signal is the conductor wire 3a,
Induction power is generated in 3b, and this induction power is transmitted to the tuner (not shown) through the two coaxial cables 5 and the connector 4. Here, by making the length of the coaxial cable connected to the conductor wire of one of the two coaxial cables 5 longer than the length of the other coaxial cable by ¼ wavelength of the transmitted wave, The phase shift is made to occur.

Therefore, the loop antenna shown in FIG. 1 has a feeding phase of 90 ° between the first and second conductor lines 3a and 3b, and can receive radio signals entering from any direction on the horizontal plane. Further, in this loop antenna, the radii of the first and second loops 1a and 1b and the number of turns of the conductor wires 3a and 3b can be set so as to be different depending on the respective applications, and the size of the antenna can be changed according to the number of turns. Could be changed.
Therefore, it has a feature that the size can be reduced as compared with other types of antennas.

[0004]

In the above-mentioned conventional loop antenna, since the loop surfaces of the conductor wires 3a and 3b, which are antenna elements, are erected vertically to the horizontal plane, the sensitivity to a horizontally polarized signal is good. However, there is a drawback that the sensitivity to vertically polarized signals is not good.

Further, in the above conventional loop antenna, when the antenna radius is reduced for the purpose of installing the loop antenna in the automobile (in this case, the radius is small, the radius is 0.03 to 0.04 wavelength or less of the transmitted wave). However, since the impedance of the antenna is reduced, the antenna gain is reduced, and reception becomes impossible. On the other hand, if the radius is increased in order to improve the gain, the antenna must be installed outside the automobile, and the antenna is easily broken and a failure is likely to occur.

Therefore, an object of the present invention is to provide a small-sized loop antenna that can be installed in a vehicle, and which can enter from all directions.
It is intended to enable high-sensitivity reception of radio wave signals such as radio broadcast signals of M and FM, television broadcast signals, and call signals of mobile communication devices.

[0007]

In order to achieve the above object, the loop antenna of the present invention has two antennas which are perpendicular to each other.
A loop-shaped first and second conductor wire having a dimensional surface and standing upright at 90 ° with respect to the horizontal plane, and a two-dimensional surface perpendicular to the two-dimensional surfaces of both the first and second conductor wires A configuration including a loop-shaped third conductor wire having a surface is adopted.

This loop antenna is literally an omnidirectional loop antenna. That is, according to this loop antenna, not only the horizontally polarized signal can be received with high sensitivity by the first and second conductor lines, but also the vertically polarized signal can be received with high sensitivity by the third conductor line.

In addition to the above omnidirectional loop antenna, the receiving apparatus of the present invention adjusts the impedance of each of the first, second and third conductor wires of the omnidirectional loop antenna. Three impedance matching circuits connected to the first, second and third conductor lines, a power combiner for combining the powers of the output signals of the three impedance matching circuits, and three power combiners A configuration including three coaxial cables for supplying the output signal of the impedance matching circuit and a microstrip amplifier for amplifying the output signal of the power combiner using the dielectric substrate and the microstrip line is adopted. It was done. Moreover, of the three coaxial cables, the length of the coaxial cable for supplying the output signal of the impedance matching circuit connected to the second conductor line to the power combiner is longer than the lengths of the other two coaxial cables. It is lengthened by 1/4 of the radio wave wavelength of the radio wave signal.

According to this receiving device, the decrease in the antenna gain due to the size reduction of the loop antenna can be compensated by the microstrip amplifier. Therefore, even a small loop antenna that can be installed in an automobile can receive various radio wave signals with sufficient gain.

In order to set the characteristic impedance of the microstrip line in the above microstrip amplifier to a preferable value of 50Ω, the thickness of the dielectric substrate is set to 1.0.
mm, and the width of the microstrip line is 1.90.
mm, and the tolerance of the width is ± 0.07 mm. Alternatively,
The thickness of the dielectric substrate is 1.6 mm, the width of the microstrip line is 3.05 mm, and the tolerance of the width is ± 0.1.
5 mm.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 2 is a circuit diagram of a receiver using the omnidirectional loop antenna according to the present invention, and FIG. 3 shows that the omnidirectional loop antenna according to the present invention and the receiver using the omnidirectional loop antenna are seated in a case. FIG. As shown in FIGS. 2 and 3, the receiving device 100 of the present invention includes a loop assembly 100a, a substrate 100b, and three coaxial cables 50 for electrically coupling the loop assembly 100a and the substrate 100b. Is roughly divided into

The loop assembly 100a has three cylindrical loops, in which conductor wires 30a, 30b and 30c as antenna elements are wound on the outer peripheral surface, that is, first, second and third loops each having a concave groove portion formed on the outer peripheral surface. Third loop 10a, 10
b, 10c, and each loop is a conductor wire 30a, 3
It functions as a support for supporting 0b and 30c.

In countries such as Korea, the United States and Europe,
Vertically polarized waves are used for radio broadcasting, and horizontally polarized waves are used for television broadcasting. The first conductor line 30a and the second conductor line 30b are erected at 90 ° with respect to the ground (horizontal plane) so as to be orthogonal to each other in order to receive a horizontally polarized signal such as a television broadcast signal. . However, these 2
One conductor line 30a, 30b is not sufficient to receive a vertically polarized signal. In order to solve this problem, the third conductor wire 30c parallel to the horizontal plane is installed. That is, the third conductor wire 30c installed horizontally has a small radius (for example, 0.03 to 0.04 wavelength or less of the transmitted wave).
In addition, like a small dipole antenna, it has omnidirectional characteristics on a horizontal plane and sin θ directional characteristics on a vertical plane. Therefore, the third conductor wire 30
Through c, the AM and FM radio broadcast signals which are vertically polarized signals can be received with high sensitivity.

The radio frequency signals obtained from the three conductor lines 30a, 30b, 30c are passed through the three impedance matching circuits 40 and the three coaxial cables 50, and the substrate 1
It is transmitted to the three connectors 45 on 00b. Each impedance matching circuit 40 is composed of an inductor L and a capacitor C, and is connected to each of the conductor lines 30a, 30b, 30c so as to improve the antenna sensitivity.
It is attached to the inner peripheral surface of a, 10b, 10c (FIG. 3). Although not clearly shown in the drawing, each conductor wire 30a, 30
The inductor L is electrically connected in series to one end of each of b and 30c, and the capacitor C is electrically connected in parallel to each other. The ground electrode of each impedance matching circuit 40 is connected to the other end of each conductor wire 30a, 30b, 30c. It is connected. The center conductor of each coaxial cable 50 is connected to the connection point between the inductor L and the capacitor C, and the outer conductor of each coaxial cable 50 is connected to the ground electrode. In order to make the horizontal directional characteristic of the antenna circular, the first and second conductor lines 30a, 30b
The phase difference between the signals respectively received at 90 ° must be 90 °. Therefore, the second of the three coaxial cables 50
The length of the coaxial cable connected to the conductor wire 30b of No. 2 is the same as that of the other two cables connected to the first and third conductor wires 30a and 30c.
It is made longer than the length of the coaxial cable by 1/4 of the wavelength of the transmitted wave.

The substrate 100b has three conductor wires 30a,
A power combiner 60 for combining the power of signals received by the three coaxial cables 50 and the three connectors 45 received by 30b and 30c, and a low power amplifier for amplifying the signals output from the power combiner 60. A noise broadband amplifier 70 is provided. The low noise wide band amplifier 70 is operated by applying a microstrip amplifier technique using an epoxy substrate 70a and a microstrip line 70b. Low Noise Wideband Amplifier 70 in the Present Invention
Is a mini circuit company (Mi
ni-Circuits Co. ) MA manufactured and sold in
It is preferable to utilize an R series model amplifier.

Receiving device 100 configured as described above
Is seated and fixed inside the case 100d as shown in FIG. The case 100d is connected to the lid 100c and installed behind the rear seat in the automobile. Furthermore, case 100
A plurality of stop lights 80 interlocked with the brakes of the automobile are attached to the inner wall of d.

The three conductor lines 30 shown in FIGS.
Radio frequency signals such as AM and FM radio broadcast signals, TV broadcast signals, and ringing signals of mobile communication devices received by omnidirectional loop antennas having a, 30b, and 30c as antenna elements have three matching impedances of 50Ω. The impedance matching circuit 40, the three coaxial cables 50, and the three connectors 45 guide the power to the power combiner 60 and combine the power combiner 60. However, since the output signal of the power combiner 6 is weak, it is amplified by the low noise wide band amplifier 70 and then transmitted to a radio receiving device such as a tuner of a radio.

The signal output from the power combiner 60 is amplified by the low noise wide band amplifier 70 by about 15 [dB]. The overall gain of the receiving apparatus 100 at this time is as follows: loop antenna gain + amplifier gain-power combiner loss-connector loss = 1.76 [dBi] +15 [dB] -3 [dB] -1.2 [DB] = 12.56 [dBi], which is already in practical use for an automobile antenna (1/4
Approximately 6 from 4.7 [dBi] of gain of wavelength grounded antenna)
Double performance improvement can be achieved. That is, the reduction in antenna gain due to the reduction in size of the loop assembly 100a can be compensated by the low noise wideband amplifier 70. Therefore, the radio wave signal can be received with sufficient gain by the small receiving device 100 that can be installed in the automobile.

A special microstrip amplifier technique is applied to the present invention. That is, the epoxy substrate 70a, which is a dielectric substrate, is used in the low frequency band, and the characteristic impedance Zo of the microstrip line 70b is set to 50Ω according to the thickness H of the epoxy substrate 70a. Determine the width W. On the other hand, the impedance of the coaxial cable of a radio receiving device such as a radio tuner connected to the output side of the microstrip line 70b is generally 75Ω.
Therefore, for impedance matching between the microstrip line 70b and the coaxial cable of the wireless reception device, the width of the microstrip line 70b is gradually narrowed on the output side so that the characteristic impedance becomes 75Ω on the wireless reception device side. To do.

The width W of the microstrip line 70b is
If W / H ≦ 1, then W / H ≧ 1
In the case of, each is determined by the following Equation 2. Here, εr is the relative permittivity and ε'r is the effective relative permittivity.
The relative permittivity εr of the epoxy substrate 70a is 45 ± 0.
It is 1.

[0022]

[Equation 1]

[0023]

[Equation 2]

In the low noise wide band amplifier 70 to which the above microstrip amplifier technique is applied, the thickness H of the epoxy substrate 70a and the microstrip line 70b are used.
And the width W of each of them are set to be different depending on the intended use.

Specifically, the microstrip line 70
According to Equation 2, the width W of the microstrip line 70b when the characteristic impedance Zo of b is 50Ω is H = 0.6 mm, W = 1.15 (± 0.05 mm), and H = 0.8 mm. , W = 1.50 (± 0.05 mm) H = 1.0 mm, W = 1.90 (± 0.07 mm) H = 1.2 mm, W = 2.25 (± 0.10 mm) When H = 1.6 mm, W = 3.05 (± 0.15 mm). Here, the numerical value in parentheses represents the tolerance of the width W.

The width W of the microstrip line 70b in the case where the characteristic impedance Zo of the microstrip line 70b is 75Ω is calculated from Equation 1 when H = 0.6 mm and W = 0.50 (± 0.03 mm). ) When H = 0.8 mm, W = 0.70 (± 0.03 mm) When H = 1.0 mm, W = 0.85 (± 0.05 mm) When H = 1.2 mm, W = 1 .05 (± 0.10 mm) When H = 1.6 mm, W = 1.40 (± 0.10 mm). Here, the numerical value in parentheses represents the tolerance of the width W.

As described above, according to the configurations of FIGS. 2 and 3, since the horizontal third loop 10c is added to each of the first and second loops 10a and 10b which are upright, the vertical plane, the horizontal plane, etc. It is possible to obtain an omnidirectional loop antenna capable of receiving various radio wave signals with high sensitivity by having directivity in all of the above. Further, since the low noise wide band amplifier 70 compensates for the antenna gain, the receiving device 100 including the loop assembly 100a is downsized. Further, since the stop lamp 80 that lights up when the brake of the automobile is operated is installed in the antenna case 100d, there is an advantage that the driver of the rear vehicle can be notified of the warning signal.

The present invention has been described above with reference to the drawings.
The present invention is not limited to the above example. For example, in the drawings, the description has been given only to a circular loop antenna, but the shape can be applied to a square, rectangular, or other loop antenna without deviating from the scope of the idea or configuration of the present invention.
It is easily understood by a person having ordinary knowledge in the technical field to which the present invention belongs.

[0029]

As described above, according to the omnidirectional loop antenna of the present invention, the loop-shaped first and second loop antennas each have two-dimensional planes perpendicular to each other and are upright at 90 ° with respect to the horizontal plane. A second conductor wire and the first and second conductor wires
Since a configuration including a loop-shaped third conductor line having a two-dimensional plane perpendicular to both two-dimensional planes of the conductor line is adopted, various types of horizontal polarization signals and vertical polarization signals are included. Any radio wave signal can be received with high sensitivity.

Further, according to the receiving apparatus of the present invention, the reduction of the antenna gain due to the size reduction of the omnidirectional loop antenna is compensated by the microstrip amplifier, so that a small loop antenna that can be installed in a vehicle is provided. However, there is an advantage that various radio wave signals can be received with a sufficient gain.

[Brief description of drawings]

FIG. 1 is a perspective view showing a conventional loop antenna.

FIG. 2 is a circuit diagram of a receiver using an omnidirectional loop antenna according to the present invention.

FIG. 3 is a perspective view showing that the omnidirectional loop antenna according to the present invention and a receiving device using the same are seated in a case together with a stop light.

[Explanation of symbols]

 10a 1st loop 10b 2nd loop 10c 3rd loop 30a, 30b, 30c Conductor wire 40 Impedance matching circuit 50 Coaxial cable 60 Power combiner 70 Low noise broadband amplifier 70a Epoxy board 70b Microstrip line 80 Stop light 100 Reception Device 100a Loop assembly 100b Substrate 100c Lid 100d Case

Claims (4)

[Claims] 1. An omnidirectional loop antenna for receiving a radio wave signal entering from all directions, each having two-dimensional planes perpendicular to each other and standing upright at 90 ° with respect to a horizontal plane. And a second conductor wire, and a loop-shaped third conductor having a two-dimensional surface perpendicular to both the two-dimensional surface of the first conductor wire and the two-dimensional surface of the second conductor wire. An omnidirectional loop antenna, comprising: 2. A loop-shaped first and second conductor wire having two-dimensional planes perpendicular to each other and standing upright at 90 ° with respect to a horizontal plane so as to receive radio wave signals coming from all directions. And a loop-shaped third conductor wire having a two-dimensional surface perpendicular to both the two-dimensional surface of the first conductor wire and the two-dimensional surface of the second conductor wire Loop antenna, three impedance matching circuits connected to the first, second and third conductor lines so as to adjust the impedance of each of the first, second and third conductor lines, A power combiner for combining the powers of the output signals of the three impedance matching circuits, three coaxial cables for supplying the output signals of the three impedance matching circuits to the power combiner, and a dielectric substrate. With microstrip line A microstrip amplifier for amplifying an output signal of the power combiner using the output signal of an impedance matching circuit connected to the second conductor line of the three coaxial cables. The receiving device is characterized in that the length of the coaxial cable for supplying to the antenna is longer than the lengths of the other two coaxial cables by 1/4 of the radio wave wavelength of the radio wave signal. 3. The dielectric substrate has a thickness of 1.0 mm, and the microstrip line has a width of 1.90 m.
The receiver according to claim 2, wherein the tolerance of m is ± 0.07 mm. 4. The dielectric substrate has a thickness of 1.6 mm, and the microstrip line has a width of 3.05 m.
3. The receiver according to claim 2, wherein the tolerance of m is ± 0.15 mm.