JP2005124030A - Spherical dipole antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spherical dipole antenna for reliably and precisely carry out a measurement of electromagnetic field over a wide band. <P>SOLUTION: The spherical dipole antenna 1a is provided with semi-spherical antenna elements 2 and 5 which are opposed to each other and each of which has a hollow, disks 4 and 7 which are respectively attached to the opposed surfaces of the antenna elements 2 and 5 and each of which is provided with tapered parts, an O/E (optical/electrical) converter 12 which converts optical signals into electrical signals and applies the electrical signals to the antenna elements 2 and 5, and an isolator 14 which prevents a reflected wave generated at the time of the application of the electrical signals from flowing in the O/E converter 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a spherical dipole antenna that emits electromagnetic waves and receives electromagnetic waves in electromagnetic field measurement.

  In order to accurately measure EMI (Electromagnetic Interference), a phenomenon in which unwanted electromagnetic waves generated from electronic devices affect broadcast receivers such as televisions and radios, measurement equipment such as open sites and anechoic chambers is required. Also, in order to evaluate these characteristics, it is necessary to emit and receive standard electromagnetic waves.

A spherical dipole antenna is used to emit and / or receive the above-described electromagnetic wave, and has two hemispherical antenna elements, and an optical / electrical converter (hereinafter referred to as “electric / electrical converter”). , An “O / E converter” as appropriate), an electric / optical converter (hereinafter referred to as an “E / O converter” as appropriate), a power supply unit, an amplifier, and the like (for example, see Non-Patent Document 1).
"Spherical dipole antenna using optical / electrical converter" Murakawa, Kuwahara, Amemiya; IEICE Transactions B-II Vol. J74-B-II No.12 pp.699-706 (1991, December)

  The above-mentioned spherical dipole antenna is for making it possible to radiate and / or receive electromagnetic waves in a high band ranging from 10 MHz to several tens of GHz, for example, and to provide two antenna elements with a tapered portion. By changing the distance between the antenna elements, electromagnetic radiation and measurement can be realized over a wide band.

  However, there is a problem that the applied voltage to the antenna element is reflected at the feeding point or the antenna element itself, and the applied voltage fluctuates due to the reflected component.

  In order to suppress this, an attempt has been made to reduce the reflected power by inserting an attenuator of several dB into the O / E converter, but there are problems such as suppressing the applied voltage itself. .

  In addition, when the electromagnetic wave is received by the antenna element, there is a problem that the electromagnetic wave once received leaks outside the antenna.

  Therefore, it has been difficult to efficiently radiate and / or receive electromagnetic waves.

  In view of such circumstances, an object of the present invention is to provide a spherical dipole antenna for reliably and accurately performing electromagnetic field measurement in a wide band.

  The present invention according to claim 1 is a hemispherical first and second antenna element, each of which is disposed opposite to each other and having a hollow portion, and opposite surfaces of the first and second antenna elements. Tapered portions provided in various ways, optical / electrical conversion means for converting an optical signal into an electric signal and applying the electric signal to the first and second antenna elements, an output side of the optical / electrical conversion means, and an antenna element And a reflected wave inflow prevention means for preventing a reflected wave generated when an electric signal is applied from flowing into the optical / electrical conversion means.

  According to a second aspect of the present invention, in the first aspect of the invention, all of the optical / electrical conversion means and the reflected wave inflow prevention means are placed in the hollow portion of the first antenna element or the second antenna element. The gist is that they are arranged close to each other.

  The gist of the present invention described in claim 3 is that, in the invention described in claim 1 or 2, the reflected wave inflow prevention means includes any one of a circulator, an isolator, and an attenuator.

  According to a fourth aspect of the present invention, hemispherical first and second antenna elements, which are arranged opposite to each other and each have a hollow portion, and the first and second antenna elements receive electromagnetic waves. When the electromagnetic wave is received and connected between the antenna element and the input side of the electric / optical conversion means, the electric / optical conversion means for converting the electric signal generated when The gist is to have electromagnetic wave leakage prevention means for preventing leakage.

  According to a fifth aspect of the present invention, in the invention of the fourth aspect, all of the electrical / optical conversion means and the electromagnetic wave leakage prevention means are mutually connected in the hollow portion of the first antenna element or the second antenna element. The gist is that they are arranged close to each other.

  The gist of the present invention described in claim 6 is that, in the invention described in claim 4 or 5, the electromagnetic wave leakage prevention means includes any one of a circulator, an isolator and an attenuator.

  The spherical dipole antenna of the present invention has reflected wave inflow prevention means for preventing a reflected wave generated when an electric signal is applied from flowing into the optical / electrical conversion means.

  Moreover, it has an electromagnetic wave leakage prevention means for preventing the electromagnetic wave from leaking outside when the electromagnetic wave is received.

  Therefore, according to the present invention, it is possible to provide a spherical dipole antenna for reliably and accurately performing electromagnetic field measurement in a wide band.

The spherical dipole antenna of the present invention will be described below with reference to the drawings.
The following examples are only for the purpose of explaining the present invention and do not limit the scope of the present invention. Accordingly, those skilled in the art can employ various embodiments including each or all of these elements, and these embodiments are also included in the scope of the present invention.
In all the drawings for explaining the embodiments, the same elements are given the same reference numerals, and the repeated explanation thereof is omitted.

FIG. 1 is a perspective view of a spherical dipole antenna 1a according to a first embodiment (embodiment 1) of the present invention.
The spherical dipole antenna 1a has antenna elements 2 and 5 made of conductors arranged to face each other via an insulating portion 8 or the like. The spherical dipole antenna 1a has a spherical portion constituted by the antenna elements 2 and 5 of this embodiment. The diameter is assumed to be about 10 cm to about 20 cm, and the weight is assumed to be about 3 kg.

  The antenna element 2 is composed of a hemispherical shape, in other words, a dome-shaped hemispherical portion 3 and a disc-shaped disc portion 4, and the antenna element 5 is a hemispherical portion 6 similar to the hemispherical portion 3 and a disc portion similar to the disc portion 4. It consists of seven.

  In addition, in this figure, although the case where the lower part of the antenna element 5 is attached to the support pole 10 via the attachment part 9 is shown, it is not limited to this and various attachment methods are employable.

FIG. 2 is a cross-sectional view of the spherical dipole antenna 1a shown in FIG. In addition, in this figure and subsequent figures, description of the attaching part 9 and the support pole 10 of FIG. 1 is omitted.
As shown in the figure, the interiors of the antenna elements 2 and 5 are hollow, and they are disposed so as to be opposed to each other by a central conductor portion 11 that penetrates the disk portions 4 and 7 and an insulating portion 8 that surrounds the center conductor portion 11. For the insulating portion 8, Teflon (registered trademark) or the like is used. Moreover, the disk part 4 and the center conductor part 11 are electrically connected.

  The spherical dipole antenna 1a is intended for electromagnetic wave radiation. For this reason, an optical / electrical converter 12 (hereinafter referred to as “O” as appropriate) disposed in the hollow portion of the antenna element 5 in a state of being close to each other. / E converter 12 ”), a power supply unit 13 connected to the O / E converter 12, an isolator 14, and an externally installed electric / optical converter 16 (hereinafter referred to as“ E / O conversion as appropriate ”). An optical fiber cable 15 for connecting the O / E converter 12 and the E / O converter 16, and an oscillator 17 connected to the E / O converter 16.

  The isolator 14 is disposed between the output side of the O / E converter 12 and the antenna element 5 (disk portion 7) and the central conductor portion 11. The O / E converter 12 is interposed via the isolator 14. The antenna element 5 and the central conductor portion 11 are connected.

  Moreover, each of the disk parts 4 and 7 has a taper part which tapers toward the outer peripheral direction from the center conductor part 11 in the opposing surface side, and also the cross-sectional shape is comprised by the curve. That is, the space portion between the antenna element 2 and the antenna element 5 has a shape that widens toward the outer peripheral portion.

  Since this taper portion has the above-described shape, the drive point impedance and the spatial characteristic impedance when the voltage (electrical signal) is applied between the disc portion 7 and the disc portion 4 via the central conductor portion 11 are moderated. The resonance phenomenon in the antenna elements 2 and 5 is suppressed by changing and improving the matching between the output impedance of the O / E converter 12 and the characteristic impedance of the space. As a result, electromagnetic waves can be transmitted and / or received in the tens of GHz band, or both.

  Next, the operation of the spherical dipole antenna 1a will be described.

  First, an electrical signal is generated in the oscillator 17 and transmitted to the E / O converter 16. The E / O converter 16 that has received the electrical signal generates a light intensity modulation signal proportional thereto. This optical signal is transmitted to the O / E converter 12 via the optical fiber cable 15. The O / E converter 12 converts the received optical signal into an electric signal and applies it between the disk portion 7 and the central conductor portion 11 via the isolator 14. When the applied electrical signal propagates between the disk part 4 and the disk part 7 in the outer circumferential direction, the characteristic impedance of the disk parts 4 and 7 changes gently due to the action of the taper part, and therefore the electromagnetic wave Reflection and resonance are suppressed, and electromagnetic waves can be radiated efficiently and accurately when performing electromagnetic field measurement.

  The isolator 14 prevents a reflected wave generated when an electric signal is applied to the antenna elements 2 and 5 from flowing into the optical / electrical conversion means.

  In this isolator 14, the insertion loss from the input side to the output side is approximately 1 dB or less, but the insertion loss from the output side to the input side (loss of reflected waves generated in the antenna elements 2 and 5 etc.) is usually 15 dB. That's it. As a result, the influence of the reflected waves generated by the antenna elements 2 and 5 on the O / E converter 12 can be made extremely small.

  The O / E converter 12 is included in the optical / electrical conversion means described in the claims, and the isolator 14 is included in the reflected wave inflow prevention means described in the claims.

FIG. 3 is a cross-sectional view of a spherical dipole antenna 1b according to a second embodiment (embodiment 2) of the present invention.
The spherical dipole antenna 1a of FIG. 3 shows the case where the O / E converter 12, the power supply unit 13, and the isolator 14 are all provided in the lower antenna element 5, but the spherical dipole antenna 1b The / E converter 12, the power supply unit 13, and the isolator 14 are all arranged in a state of being close to the upper antenna element 2.

  By adopting such a configuration, the exposed portion of the optical fiber cable 15 in the hollow portion in the antenna element can be greatly reduced. For example, when replacing the battery in the power supply unit 13 or the like, It is possible to prevent the optical fiber cable 15 from being damaged when checking the output voltage of the E converter, and it is only necessary to remove the hemispherical portion 3 without having to remove the entire spherical dipole antenna 1b from the support pole 10 of FIG. Thus, it becomes possible to carry out the above work, and the workability can be improved.

FIG. 4 is a cross-sectional view of a spherical dipole antenna 1c according to a third embodiment (third embodiment) of the present invention.
The spherical dipole antenna 1c is a modification of the above-described spherical dipole antenna 1b (FIG. 3), and is intended to receive electromagnetic waves. Therefore, the antenna element 5 has an E / O converter 16, an isolator 14, and a power supply unit 13 connected to the E / O converter 16. The O / E converter 12 and the O / E converter 12 are connected to the outside. The optical fiber cable 15 that connects the / E converter 12 and the E / O converter 16 and the receiver 18 that is connected to the O / E converter 12 are included.

  The isolator 14 is disposed between the input side of the E / O converter 16 and the antenna element 5 (disk portion 7) and the central conductor portion 11. The E / O converter 16 is interposed via the isolator 14. The antenna element 5 and the central conductor portion 11 are connected.

  It should be noted that the functions, configurations, etc. of other elements are not changed and are the same as those shown in the first embodiment. The E / O converter 16 is included in the electrical / optical conversion means described in the claims.

  Next, the operation of the spherical dipole antenna 1a will be described.

  The electromagnetic waves arriving at the antenna elements 2 and 5 enter the tapered portion between them and are received. As a result, a voltage (electric signal) is generated between the disk portion 4 and the central conductor portion 11. The generated voltage is converted into a light intensity modulation signal by the E / O converter 16. This optical signal is transmitted to the external O / E converter 12 via the optical fiber cable 15. The O / E converter 12 converts the received optical signal into an electrical signal. Since the level of this electric signal is proportional to the electromagnetic wave intensity, the electromagnetic wave received by the antenna elements 2 and 5 can be measured by receiving this electric signal by the receiver 18.

  In addition, since the characteristic impedance of the disk parts 4 and 7 changes gently due to the action of the taper part, reflection and resonance of electromagnetic waves are suppressed, and electromagnetic waves can be received efficiently and accurately when performing electromagnetic field measurement. Can do.

  The isolator 14 prevents the electromagnetic waves from leaking outside the spherical dipole antenna 1c when the electromagnetic waves are received by the antenna elements 2 and 5.

  In this isolator 14, the insertion loss from the input side to the output side is approximately 1 dB or less, but the insertion loss from the output side to the input side (loss of reflected waves generated in the antenna elements 2 and 5 etc.) is usually 15 dB. That's it. As a result, the electromagnetic waves received by the antenna elements 2 and 5 can be prevented from leaking outside the spherical dipole antenna 1c.

  The E / O converter 16 is included in the electrical / optical conversion means described in the claims, and the isolator 14 is included in the electromagnetic wave leakage prevention means described in the claims.

FIG. 5 is a cross-sectional view of a spherical dipole antenna 1d according to a fourth example (Example 4) of the present invention.
The spherical dipole antenna 1d is a modification of the spherical dipole antenna 1b (FIG. 3) and 1c (FIG. 4) described above, and is intended for both emission and reception of electromagnetic waves. Therefore, an O / E converter 12a, an isolator 14, an optical fiber cable 15a, an E / O converter 16a and an oscillator 17 for radiation of electromagnetic waves, and an E / O converter 16b for receiving electromagnetic waves, an isolator 14, the optical fiber cable 15b, the O / E converter 12b and the receiver 18, and the O / E converter 12a and the E / O converter 16b, and the disk portion via the two isolators 14 4 and a directional coupler 19 connected to the central conductor 11 and a power supply 13 connected to each of the O / E converter 12a and the E / O converter 16b.

  The O / E converters 12a and 12b are the same as the above-described O / E converter 12 (FIGS. 2 to 4), and the E / O converters 16a and 16b are the above-described E / O converters 16 and 16 respectively. It is the same as (FIGS. 2 to 4).

  Since the directional coupler 19 passes the electric signal output from the O / E converter 12a as it is, the directional coupler 19 can radiate electromagnetic waves from the antenna elements 2 and 5, and further generates an electric signal when the electromagnetic waves are received. Only this signal is demultiplexed and this electric signal is transmitted to the E / O converter 16b.

  The functions, configurations, etc. of other elements are not changed and are the same as those shown in the first to third embodiments. Alternatively, only one power supply unit 13 may be provided, and power may be supplied from this power supply unit to both the O / E converter 12a and the E / O converter 16b.

  Further, in all the embodiments described above, the case where each of the disk parts 4 and 7 is formed integrally with the taper part is shown, but the present invention is not limited to this, and the disk part and the taper part are separated from each other. It is good also as a structure which produces as a member and joins later.

  In all the above embodiments, the hemispherical part 3 and the disk part 4 and the hemispherical part 6 and the disk part 7 are separately formed. However, the hemispherical part and the disk part are integrated. You may form in.

  In all of the above embodiments, an amplifier or the like can be provided as necessary.

  Moreover, in all the embodiments described above, the case where the reflected wave inflow prevention means and the electromagnetic wave leakage prevention means are isolators is shown, but the present invention is not limited thereto, and each of the above means includes a circulator, an attenuator, and the like. It can also be.

  Further, by adopting the above configuration, interference between optical signals and interference between electrical signals can be prevented.

It is a perspective view of the spherical dipole antenna 1a which concerns on Example 1 of this invention. It is sectional drawing of the spherical dipole antenna 1a of FIG. It is sectional drawing of the spherical dipole antenna 1b which concerns on Example 2 of this invention. It is sectional drawing of the spherical dipole antenna 1c which concerns on Example 3 of this invention. It is sectional drawing of the spherical dipole antenna 1d which concerns on Example 4 of this invention.

Explanation of symbols

1a, 1b, 1c, 1d Spherical dipole antenna 2, 5 Antenna element 3, 6 Hemisphere part 4, 7 Disk part 8 Insulating part 9 Mounting part 10 Support pole 11 Central conductor part 12, 12a, 12b Optical / electrical (O / E) ) Converter 13 Power supply unit 14 Isolator 15, 15a, 15b Optical fiber cable 16, 16a, 16b Electric / optical (E / O) converter 17 Oscillator 18 Receiver 19 Directional coupler

Claims (6)

Hemispherical first and second antenna elements arranged opposite each other, each having a hollow portion;
A tapered portion provided on each of the opposing surfaces of the first and second antenna elements;
Optical / electrical conversion means for converting an optical signal into an electrical signal and applying the electrical signal to the first and second antenna elements;
Reflection connected between the output side of the optical / electrical conversion means and the antenna element to prevent a reflected wave generated when the electrical signal is applied from flowing into the optical / electrical conversion means A spherical dipole antenna comprising: a wave inflow prevention means.   2. The optical / electrical conversion means and the reflected wave inflow prevention means are all arranged in a state of being close to each other in a hollow portion of the first antenna element or the second antenna element. A spherical dipole antenna as described in 1.   The spherical dipole antenna according to claim 1, wherein the reflected wave inflow prevention means includes any one of a circulator, an isolator, and an attenuator. Hemispherical first and second antenna elements arranged opposite each other, each having a hollow portion;
An electrical / optical conversion means for converting an electrical signal generated when the first and second antenna elements receive electromagnetic waves into an optical signal;
Electromagnetic wave leakage prevention means connected between the antenna element and the input side of the electrical / optical conversion means for preventing leakage of the electromagnetic wave to the outside when the electromagnetic wave is received. Spherical dipole antenna characterized by   5. The electric / optical conversion means and the electromagnetic wave leakage prevention means are all arranged in a state of being close to each other in a hollow portion of the first antenna element or the second antenna element. The spherical dipole antenna described.   6. The spherical dipole antenna according to claim 4, wherein the electromagnetic wave leakage preventing means includes any one of a circulator, an isolator, and an attenuator.

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