JP2006166041A - Microstrip antenna with light emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microstrip antenna with a light emitting diode capable of being realized without increasing the area and the number of layers of a printed board. <P>SOLUTION: The microstrip antenna comprises: a radiation element 12; a ground conductor facing the radiation element 12; and the light emitting diode 19 provided on the radiation element 12 or the ground conductor. One terminal of the light emitting diode 19 is connected with the radiation element 12 and the other terminal is connected with the ground conductor at a part where the potential difference between the radiation element 12 and the ground conductor becomes minimum when the radiation element 12 resonates. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microstrip antenna with a light-emitting diode, and more particularly to a microstrip antenna with a light-emitting diode used in a vehicle-mounted device of a non-stop automatic toll collection system (hereinafter referred to as ETC).

  A microstrip antenna with a light emitting diode is known as an antenna used in an ETC on-vehicle device. The light emitting diode provided in the microstrip antenna is for displaying normal, abnormal, warning, etc. of the operation.

  FIG. 17 is a perspective view of an example of a conventional microstrip antenna with a light emitting diode. Referring to FIG. 1, a conventional microstrip antenna 101 with a light emitting diode is configured using a printed circuit board 45. The surface 11 of the printed circuit board 45 has a radiating element 12, a light emitting diode (hereinafter referred to as LED) 51, a through hole 52, a quarter-wavelength microstrip line 53, a land 54, and a transformer. 55, and a ground conductor (not shown) is disposed on the back surface 17. The land 54 is connected to the ground conductor on the back surface 17 through the through hole 52.

  The LED 51, the through hole 52, the quarter-wavelength microstrip line 53, the land 54, and the transformer 55 constitute an LED circuit. The LED circuit is a circuit for eliminating the influence of the microwave signal and supplying only the DC voltage necessary for driving the LED 51 to the LED 51.

  This LED circuit has an impedance transformer 55 that is a quarter of the wavelength of the frequency used. The line width of the impedance transformer 55 is about 0.2 mm, and the characteristic impedance is a microstrip line of about several hundred ohms.

  At the tip of the transformer 55, a microstrip line 53 of about 50 ohms is formed with a length of one quarter of the wavelength. Further, an LED 51 is provided at a connection portion between the transformer 55 and the microstrip line 53 having a quarter wavelength. Further, one terminal of the LED 51 is connected to the connecting portion, and the other terminal is connected to the land 54.

  On the other hand, power is supplied from the feed point 14 provided at the end of the radiating element 12 via the microstrip line 53.

  18 and 19 are perspective views of another example of a conventional microstrip antenna with a light emitting diode, and FIG. 20 is a sectional view of the antenna. FIG. 18 shows the front surface of the antenna, and FIG. 19 shows the back surface.

  Referring to FIGS. 18 to 20, another example of a conventional microstrip antenna with a light emitting diode includes a first layer, a second layer, and a third layer. A radiation element 62 is formed on the first layer, a ground conductor 66 is formed on the second layer, a microstrip line 55, an LED circuit including the LED 51, and a land 57 are formed on the third layer. .

  A through-hoe 64 is provided at a position (offset position) away from the center of the radiating element 62 by a predetermined distance. The through hole 64 is connected to the third layer. A circular notch 68 is provided at the position of the through hole 64 of the ground conductor 66 and is electrically insulated from the through hole 64.

  The microstrip line 55 is connected to the through hole 64. The LED circuit including the LED 51 has the same configuration as the above-described conventional LED circuit (see FIG. 17).

  The land 57 of the LED circuit is connected to the ground conductor 66 of the second layer through the through hole 52.

  On the other hand, an electromagnetic wave generating device in which a photodiode is disposed in an opening of a semiconductor substrate is disclosed as an example of another prior art (see Patent Document 1). This is to irradiate a photodiode with laser light and supply the generated electric signal to a patch antenna.

  In addition, as an example of another conventional technique, a printed antenna board in which LEDs are arranged on a printed antenna is disclosed (see Patent Document 2).

  Moreover, an example of a radiation element of a general microstrip antenna is disclosed (see Non-Patent Document 1).

Japanese Patent Laying-Open No. 2002-246838 (paragraphs 0012 and 0013, FIG. 2A) JP 2004-36370 A (paragraph 0007, FIG. 1) Osamu Haneishi, “Small / Plane Antenna”, IEICE, August 10, 1996, p142 Fig. 5.1, p146 Fig. 5.4

  However, the conventional microstrip antenna needs to add an LED circuit on the printed circuit board in order to mount the LED. In order to add this LED circuit, it is necessary to increase the area of the printed circuit board by that amount (see FIG. 17) or increase the number of layers of the printed circuit board from 2 layers to 3 layers or more (see FIG. 17). 18-20).

  For this reason, the conventional microstrip antenna has a problem of increasing the cost of the printed circuit board and increasing the size of the antenna.

  On the other hand, the technique described in Patent Document 1 is a technique for mounting a photodiode, and is a technique that is completely different in purpose, configuration, and effect from a technique for mounting a light-emitting diode intended to emit light, and solves the above problems. Means are not disclosed.

  Further, the technology described in Patent Document 2 does not touch on LED circuits for driving LEDs at all, and its purpose, configuration and effect are completely different from those of the present invention, and means for solving the above-mentioned problems are disclosed. Not.

  Further, Non-Patent Document 1 does not disclose means for solving the above problem.

  Accordingly, an object of the present invention is to provide a microstrip antenna with a light emitting diode that can be realized without increasing the area and the number of layers of a printed circuit board.

  In order to solve the above problems, a microstrip antenna with a light emitting diode according to the present invention includes a radiating element, a ground conductor facing the radiating element, and a light emitting diode provided on the radiating element or the ground conductor. The light-emitting diode has one terminal connected to the radiating element at a portion where the potential difference between the radiating element and the ground conductor is minimized when the radiating element resonates, and the other terminal. Is connected to the ground conductor.

  According to the present invention, since the light emitting diode is connected at a portion where the potential difference between the radiating element and the ground conductor is minimized when the radiating element resonates, a circuit for driving the light emitting diode (LED circuit) becomes unnecessary.

  According to the present invention, the light emitting diode is configured to be connected to the radiating element and the ground conductor at a portion where the potential difference between the radiating element and the ground conductor is minimized when the radiating element resonates. The light emitting diode can be caused to emit light by applying a DC voltage via the strip line. Therefore, a circuit for driving a light emitting diode (LED circuit) is not required, and a microstrip antenna with a light emitting diode can be obtained without increasing the area and the number of layers of the printed board.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 and 2 are perspective views of a first embodiment of a microstrip antenna with a light emitting diode according to the present invention, and FIG. 3 is a cross-sectional view of the embodiment. FIG. 1 shows the front surface of the antenna, and FIG. 2 shows the back surface.

  Referring to FIG. 1, the microstrip antenna 1 with a light emitting diode is constituted by a printed circuit board 45, on which a radiating element 12, a through hole 13, and a feeding point 14 are arranged.

  As an example of the dielectric material of the printed circuit board 45, glass epoxy resin, PTFE (Poly Tetra Fluoro Ethylene) resin, or the like is used. The size of one side of the printed circuit board 45 is about a half wavelength at the used frequency.

  A radiation element 12 that transmits and receives a microwave signal is formed on the surface 11 of the printed circuit board 45 by etching. The shape of the radiating element 12 is substantially square, and two of the four corners facing each other are formed in a chamfered cutout 16. This notch 16 is formed to transmit and receive a circularly polarized microwave signal.

  The size of one side of the radiating element 12 depends on the dielectric constant and thickness of the dielectric of the printed circuit board 45 and becomes a predetermined size. For example, in the case of glass epoxy resin, the size is about 25% of the wavelength used, but in the case of PTFE resin, it is about 35%.

  A feeding point 14 is formed at a position (offset position) away from the center of the radiating element 12 by a predetermined distance. A small through hole (not shown) that allows the central conductor of the coaxial cable to pass therethrough is formed at the feeding point 14, and the central conductor of the coaxial cable is inserted into the through hole from the back surface. The tip of the center conductor is soldered 15 to the radiating element 12 and both are electrically connected. A through hole 13 is formed at the center of the radiating element 12.

  2 and 3, a ground conductor 18, a light emitting diode (LED) 19, a land 26, and a coaxial cable 22 are provided on the back surface 17 of the printed circuit board 45.

  The ground conductor 18 covers the entire back surface 17 of the printed circuit board 45, the land 26 is provided at the center thereof, and a notch 25 is formed around the through hole of the coaxial cable 22.

  The land 26 is formed with the ground conductor 18 through the narrow gap 20. Further, the through hole 13 makes the radiating element 12 on the printed board surface 11 and the land 26 formed on the printed board back surface 11 conductive.

  The outer conductor 24 of the coaxial cable 22 is soldered 23 to the ground conductor 18 on the back surface 17 of the printed circuit board. The center conductor 21 is soldered 15 to the radiation element 12 on the surface 11 of the printed circuit board 45 through the through hole.

  The LED 19 is configured between the land 26 and the ground conductor 18. The anode terminal 19 a of the LED 19 is connected to the land 26. The cathode terminal 19 b of the LED 19 is connected to the ground conductor 18. The LED 19 is usually mounted by machine mounting.

  Next, the operation of this embodiment will be described separately for the operation of the LED 19 and the operation of the antenna. First, the operation of the LED 9 will be described.

  A DC voltage for causing the LED 19 to emit light is applied to the coaxial cable 22. For example, in the case of a light emitting diode with a rated quasi-current of 20 mA, a voltage of about 2.2 V is applied. The applied DC voltage is applied to the anode terminal 19 a of the LED 19 through the radiating element 12, the through hole 13, and the land 26. Since a predetermined voltage is applied to the anode terminal 19a of the LED 19, a direct current flows through the LED 19 to emit light.

  Next, the operation as an antenna will be described along the flow of a microwave signal in the case of transmission. A microwave signal having a use frequency is input from the coaxial cable 22. For example, in the case of an ETC system, a microwave signal near 5.8 GHz is used.

  The microwave signal is fed from the central conductor 21 of the coaxial cable 22 to the printed circuit board surface 11, the radiating element 12 resonates at the operating frequency, and is transmitted as a radio wave from the radiating element 12.

  In this embodiment, the radio wave radiates circularly polarized waves. When the radiating element 12 resonates at the operating frequency, the voltage near the center of the radiating element 12 is 0 v, and there is almost no potential difference from the back surface 17 of the printed circuit board.

  Therefore, there is almost no potential difference between the anode terminal 19 a connected to the radiating element 12 of the LED 19 and the cathode terminal 19 b connected to the ground conductor 18.

  Although the impedance at the operating frequency of the LED 19 varies depending on the magnitude of the direct current generated by the direct current voltage applied to the LED 19, the microwave signal does not flow through the LED 19 as described above.

  That is, since the microwave signal of the use frequency does not flow through the LED 19, the operation as a microstrip antenna is not affected. Specifically, mounting the LED 19 on the microstrip antenna causes slight deviations in input impedance and resonance frequency, but this does not affect the explanation of the qualitative operation of this embodiment.

  Actually, the size of the radiating element 12 and the position of the feeding point 14 are determined so that the deviation of the input impedance and the deviation of the resonance frequency include the deviation and the desired impedance and the desired frequency.

  In the description of the operation of the present embodiment, the flow of the microwave signal at the time of transmission has been described, but at the time of reception, reversibility is achieved only by the direction of the flow of the microwave signal being reversed. Omitted.

  The operation of the LED 19 and the operation of the antenna have been described above. However, since both of them actually operate, a DC voltage and a microwave signal are superimposed on the coaxial cable 22.

As described above, the first embodiment has the following effects.
The first effect is that the LED 19 is mounted in the vicinity of the center of the antenna and the LED circuit is not required. Therefore, it is possible to prevent an increase in the area of the printed circuit board and to minimize the number of layers.

  The second effect is to prevent an increase in the area of the printed circuit board and to minimize the number of layers, thereby minimizing the size of the resin case covering the printed circuit board.

  The third effect can minimize the costs of the printed circuit board and the resin case.

  4 and 5 are perspective views of a second embodiment of the microstrip antenna with a light emitting diode according to the present invention, and FIG. 6 is a sectional view of the embodiment. 4 shows the front surface of the antenna, and FIG. 5 shows the back surface. Components similar to those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof is omitted.

  The microstrip antenna 2 with a light emitting diode of the second embodiment is different from the first embodiment in that an LED 19 is provided at the center of the radiation element 12 on the surface 11 of the printed board 45. Accordingly, the land 29 is provided at the center of the radiation element 12, a gap 30 is formed around the land 29, and the land 29 and the ground conductor 18 on the back surface 17 of the printed circuit board 45 are connected via the through hole 13. The anode terminal 19 a of the LED 19 is connected to the radiating element 12 on the surface 11 of the printed circuit board 45, and the cathode terminal 19 b of the LED 19 is connected to the land 29.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted. Since the operation is the same as that of the first embodiment, the description is omitted.

  According to the second embodiment, the LED 19 can be provided on the surface of the printed circuit board 45. Other effects are the same as those of the first embodiment.

  7 and 8 are perspective views of a third embodiment of the microstrip antenna with a light emitting diode according to the present invention, and FIG. 9 is a cross-sectional view of this embodiment. 7 shows the front surface of the antenna, and FIG. 8 shows the back surface. Components similar to those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof is omitted.

  The microstrip antenna 3 with the light emitting diode of the third embodiment is different from the first embodiment in that the structure for feeding the radiation element 12 is changed (see FIG. 7). LED19 is provided in the back surface 17 of the printed circuit board 45 similarly to 1st Example (refer FIG. 8).

  In the third embodiment, the coaxial cable 22, the through hole of the feeding point 14, and the notch 25 of the ground conductor 18 in the first embodiment are eliminated, and the microstrip line 28 is formed from the feeding point 14 provided at the end of the radiating element 12. Power is being supplied through.

  The width of the microstrip line 28 is a predetermined width corresponding to a desired input impedance. In the case of this embodiment, the width corresponds to an input impedance of about 100 to 250 ohms.

  In this embodiment, only the power feeding structure is the microstrip line 28, and the operation of the antenna and the operation of the LED 19 are the same as those of the first embodiment. Therefore, the detailed description of the configuration and operation of this embodiment is omitted. To do.

  According to the third embodiment, the coaxial cable 22, the through hole of the feeding point 14, and the notch 25 of the ground conductor 18 can be eliminated. Other effects are the same as those of the first embodiment.

  10 and 11 are perspective views of a fourth embodiment of the microstrip antenna with a light emitting diode according to the present invention, and FIG. 12 is a cross-sectional view of the same embodiment. 10 shows the front surface of the antenna, and FIG. 11 shows the back surface. Components similar to those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof is omitted.

  The difference between the microstrip antenna 4 with the light emitting diode of the fourth embodiment and the second embodiment is that the feeding structure to the radiating element 12 is changed (see FIG. 10). The feeding structure is the same as that of the third embodiment (see FIG. 7). Moreover, LED19 is provided in the surface 11 of the printed circuit board 45 similarly to 2nd Example (refer FIG. 10). Since other operations are the same as those of the third and fourth embodiments, description thereof is omitted.

  According to the fourth embodiment, the coaxial cable 22, the through hole of the feeding point 14, and the notch 25 of the ground conductor 18 can be eliminated, and the LED 19 can be provided on the surface of the printed board 45. Other effects are the same as those of the first embodiment.

  FIG. 13 is a perspective view of a fifth embodiment of the microstrip antenna with a light emitting diode according to the present invention, and FIG. 14 is a cross-sectional view of the same embodiment. FIG. 13 shows the surface of the antenna. Components similar to those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof is omitted.

  The difference between the microstrip antenna 5 with the light emitting diode of the fifth embodiment and the first embodiment is that a capacitor 31 is connected between the land 26 on the back surface 17 of the printed circuit board 45 of the first embodiment and the ground conductor 18. (Refer to FIG. 13 and FIG. 14). That is, one terminal 31 a of the capacitor 31 is connected to the ground conductor 18, and the other terminal 31 b is connected to the land 26. The capacitor 31 is mounted on the machine similarly to the LED 19.

  When a potential difference at the operating frequency occurs between the land 26 and the ground conductor 18, a microwave signal is passed through the capacitor 31. Thereby, the microwave signal which flows into LED19 can be reduced.

  In the fifth embodiment, the case where a capacitor is added to the first embodiment has been described. However, the present invention is not limited to this, and a similar capacitor can be added to the second to fourth embodiments. is there.

  According to the fifth embodiment, when the characteristic of the antenna resonance frequency or the input impedance changes due to the direct current flowing through the LED 19 in the first embodiment, the influence can be reduced.

  FIG. 15 is a perspective view of a sixth embodiment of a microstrip antenna with a light emitting diode according to the present invention, and FIG. 16 is a cross-sectional view of the same embodiment. FIG. 15 is a view of the antenna as viewed from the front side. Components similar to those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof is omitted.

  Referring to FIGS. 15 and 16, the microstrip antenna 6 with a light emitting diode of the sixth embodiment includes a radiating element 32 and a ground conductor 34 not by a printed board but by a sheet metal (metal plate). A support 33 is provided between the radiating element 32 and the ground conductor 34. The support 33 is made of plastic resin as an example. In addition, if it is an insulator, use of members other than plastic resin is also possible.

  A hole 40 is formed in the center of the radiating element 32 and the center of the ground conductor 34. A hole 39 for passing the central conductor 21 from the coaxial cable 22 is formed at a position (offset position) away from the center of the radiating element 32 by a predetermined distance.

  An LED 19 is provided near the center of the radiating element 32. The LED 19 is provided with lead wires 19a and 19b from electrodes. One lead wire 19a is soldered 42 to the center of the radiating element 32 at the anode. The other lead wire 19b passes through the hole 40 in the central portion of the radiating element 32 at the cathode, and is soldered 41 to the central portion of the ground conductor 34.

  A coaxial cable 22 is provided on the ground conductor 34 side. The center conductor 21 of the coaxial cable 22 passes through the hole 39 of the ground conductor 34 and is soldered 15 to the hole (not shown) of the radiating element 32. The outer conductor 24 of the coaxial cable 22 is soldered 23 to the ground conductor 34.

  According to the sixth embodiment, the microstrip antenna with a light emitting diode can be formed of sheet metal. Other effects are the same as those of the first embodiment.

  If this application is a microstrip antenna, it can be carried out regardless of the shape of the radiating element and the feeding method. For example, a radiating element of a general microstrip antenna is described in Non-Patent Document 1 described above. Moreover, the mounting position of LED19 should just exist in the position near the center of a radiation | emission element, or the printed circuit board back surface.

It is a perspective view of 1st Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is a perspective view of 1st Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is sectional drawing of the Example. It is a perspective view of 2nd Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is a perspective view of 2nd Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is sectional drawing of the Example. It is a perspective view of 3rd Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is a perspective view of 3rd Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is sectional drawing of the Example. It is a perspective view of 4th Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is a perspective view of 4th Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is sectional drawing of the Example. It is a perspective view of 5th Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is sectional drawing of the Example. It is a perspective view of 6th Example of the microstrip antenna with a light emitting diode which concerns on this invention. It is sectional drawing of the Example. It is a perspective view of an example of the conventional microstrip antenna with a light emitting diode. It is a perspective view of another example of the conventional microstrip antenna with a light emitting diode. It is a perspective view of another example of the conventional microstrip antenna with a light emitting diode. It is sectional drawing of the antenna.

Explanation of symbols

1 to 6 Microstrip antenna with light emitting diode 12, 32 Radiating element 13 Through hole 14 Feeding point 16 Notch 18, 34 Ground conductor 19 Light emitting diode (LED)
20, 30 Gap 22 Coaxial cable 26, 29 Land 28 Microstrip line 31 Capacitor 33 Support 45 Printed circuit board

Claims (10)

A microstrip antenna with a light emitting diode, comprising: a radiating element; a ground conductor facing the radiating element; and a light emitting diode provided on the radiating element or the ground conductor,
The light emitting diode has one terminal connected to the radiating element and the other terminal connected to the ground conductor at a portion where the potential difference between the radiating element and the ground conductor is minimized when the radiating element resonates. A microstrip antenna with a light-emitting diode. 2. The microstrip antenna with a light emitting diode according to claim 1, wherein the light emitting diode is provided at a central portion of the radiating element or a portion of the ground conductor facing the central portion. The radiation element is provided on one surface of the printed circuit board, and the ground conductor is provided on the other surface,
The light emitting diode is provided on the ground conductor, one terminal of the light emitting diode is connected to the radiating element through a through hole provided on the printed circuit board, and the other terminal of the light emitting diode is connected to the ground conductor. 3. The microstrip antenna with a light emitting diode according to claim 1, wherein the microstrip antenna is connected. The radiation element is provided on one surface of the printed circuit board, and the ground conductor is provided on the other surface,
The light emitting diode is provided in the radiating element, one terminal of the light emitting diode is connected to the radiating element, and the other terminal of the light emitting diode is connected to the ground conductor through a through hole provided in the printed circuit board. 3. The microstrip antenna with a light emitting diode according to claim 1, wherein the microstrip antenna is connected. 5. The microstrip antenna with a light emitting diode according to claim 3, wherein a capacitor is connected between one terminal of the light emitting diode and the ground conductor. 3. The microstrip antenna with a light emitting diode according to claim 1, wherein the radiating element and the ground conductor are made of a metal plate. A support member sandwiched between the radiating element and the ground conductor is included,
The light-emitting diode is provided in the radiating element, one terminal of the light-emitting diode is connected to the radiating element, and the other terminal of the light-emitting diode is connected to the radiating element and a hole provided in the ground conductor. The microstrip antenna with a light emitting diode according to claim 6, wherein the microstrip antenna is connected to a ground conductor. The microstrip antenna with a light emitting diode according to any one of claims 1 to 7, wherein the microstrip antenna is fed with a coaxial cable. A microstrip line is provided at an end of the radiating element,
The microstrip antenna with a light emitting diode according to any one of claims 1 to 5, wherein power is supplied through the microstrip line. The microstrip antenna with a light emitting diode according to any one of claims 1 to 9, wherein the microstrip antenna is used in a vehicle-mounted device of a non-stop automatic toll collection system (Electronic Toll Collection System).

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