JP4419789B2 - Notch antenna - Google Patents

Description

  The present invention relates to a communication antenna, and more particularly, to a notch antenna that enables miniaturization of the antenna itself.

  A notch antenna is known as an antenna device used for various communication devices such as communication terminals and reception devices. The notch antenna is designed to be miniaturized by opening the edge of the slot antenna, and is widely used as an antenna for small and light equipment or as an antenna with a high degree of freedom in installation. Furthermore, there is an antenna described in Patent Document 1 as an antenna of a type in which a monopole antenna is combined with a notch antenna.

In this antenna, a notch is provided at one corner of the ground conductor provided on the circuit board, the first linear conductor is disposed so as to straddle the notch, and connected to the ground conductor, from the short-circuited end of the notch A second linear conductor is arranged so as to extend to the open end, and a feeding point is provided for each. It is described that this configuration has the advantage that two antennas can be formed in the same space and that high isolation can be achieved between the two antennas.
JP 2001-102862 A

  When only the notch antenna portion of this composite antenna is taken out, the structure shown in FIG. That is, the power supply line 20 and the power supply unit 3 are arranged in a gap between notches (notches) 10 provided in the conductive substrate 1. At this time, the impedance is adjusted by the feeding position, that is, the distance d between the feeding line 20 and the short-circuit end 14. At this time, when d is 0, that is, when the feeder line 20 overlaps the short-circuit portion 14, the impedance becomes 0, and the impedance (resistance) increases as the feeding position moves toward the open end 13 side. On the other hand, since an annular current path is formed by the feed line 20 and the notch 10, the inductance (positive reactance) increases as the path length becomes shorter than the half wavelength λ / 2 of the transmission / reception wavelength λ. Resistance and reactance fluctuate simultaneously with changes, making it difficult to adjust impedance.

  In addition, as shown in FIG. 12B, there is a type in which the L-type probe 2 crosses three-dimensionally in the gap of the notch 10 and power is supplied from the power supply unit 3. In this type of notch antenna, the reactance can be adjusted by the length of the L-shaped probe 2, but the entire structure needs to be configured in three dimensions, and the degree of freedom in arrangement is reduced.

  Therefore, an object of the present invention is to provide a notch antenna in which resistance and reactance can be easily adjusted and the degree of freedom in arrangement is increased.

  In order to solve the above-described problems, a notch antenna according to the present invention has a notch having one end as an open end and the other end as a short-circuited end, and a side wall facing the open end and the short-circuited end at the end of the conductive substrate. A feeding portion electrically connected to the side wall is disposed on one side of the side wall, and a feeding probe is disposed in the projection plane of the notch when viewed from the direction perpendicular to the substrate surface of the substrate. In the notch antenna configured to be electrically connected to the feeding probe, the feeding probe extends in the direction of the opposing side wall from the feeding part, and extends in parallel with the side wall surface of the opposing side wall through at least one bent part. It is characterized by having existing parts.

  The basic configuration of this notch antenna is that an L-shaped probe is inserted into the plane inside the notch, its short side is perpendicular to the side wall (parallel to the open end / short circuit end), and the long side is parallel to the side wall (open end / It becomes a form arrange | positioned orthogonally to a short circuit end.

  The power feeding unit may be connected to the open end of the side wall. The power feeding probe may have a plurality of bent portions, or the notch may have at least one bent portion.

  According to the present invention, for example, when an L-shaped probe is inserted, the resistance is determined by the probe insertion amount (= the length of the short side), and the total length of the probe (the sum of the length of the short side and the long side). ), The reactances can be adjusted independently. Further, since the L-type probe can be arranged in the plane of the notch, the degree of freedom of arrangement can be ensured.

  When the power feeding part is connected to the open end of the side wall, the possible total length of the probe can be increased. In addition, the power supply probe can be configured to have a plurality of bent portions, or the cutout itself can be configured to have a bent portion, thereby further improving the degree of freedom of the arrangement.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.

  FIG. 1 is a front view showing a basic configuration of a notch antenna according to the present invention. A rectangular notch (notch) 10 is provided at one end of a conductive substrate (for example, a metal flat plate) 1, and the L-shaped probe 2 is disposed in the notch 10. The short side 21 of the L-shaped probe 2 is connected to the open end 13 side of the side wall 11 of the notch 10 via the power feeding unit 3. The short side 21 of the L-shaped probe 2 extends along the open end 13 in parallel to the open end 13 (in the direction from the side wall 11 to the side wall 12 facing vertically), passes through the bent portion 22, and the long side 21 23 extends perpendicularly to the short side 21 in the direction of the short-circuit end 14 (parallel to the side walls 11, 12) and is disposed in the same plane as the notch 10.

  Here, the width of the notch 10 (distance between the side walls 11 and 12) is w, and the length (distance between the open end 13 and the short-circuited end 14) is L, and the length (insertion) of the short side 21 of the L-shaped probe. (Amount) is a, and the length of the long side 23 is b.

  In this notch antenna, a potential difference is generated between the side walls 11 and 12 of the notch 10. For example, assuming that the potential of the side wall 11 on the power feeding unit 3 side is 0 volts and the potential of the opposing side wall 12 is xV, the voltage generated in the power feeding unit 3 through the L-type probe 2 increases as a is longer, that is, the L-type probe 2. Becomes higher toward the opposite side wall 12 and the feeding impedance becomes higher. As a result, resistance (corresponding to the real part of impedance) also increases. Conversely, the shorter a is, that is, the closer the L-type probe 2 is to the side wall 11 side to which the power feeding unit 3 is connected, the lower the voltage generated in the power feeding unit 3 and the lower the power feeding impedance. As a result, resistance also decreases.

  FIG. 2 is a graph showing changes in resistance and reactance (corresponding to an imaginary part of impedance) when the total length (a + b) of the L-type probe 2 is constant and the insertion amount a is changed. The change in reactance due to the change in the amount of insertion a is only slight, but the resistance varies greatly. On the contrary, it can be understood that it is sufficient to adjust the insertion amount a in order to obtain the desired resistance value.

  On the other hand, when the total length (a + b) of the L-type probe 2 becomes shorter than ¼ (= λ / 4) of the wavelength λ, the impedance becomes capacitive, and when it becomes longer than λ / 4, the impedance becomes inductive, It is reflected in the impedance.

  FIG. 3 is a graph showing changes in resistance and reactance when the insertion amount of the L-type probe 2 is constant and the total length (a + b), specifically, the length of the long side b is changed. Unlike the case where the insertion amount is changed, the change in resistance due to the change in the total length a + b is only slight, but the reactance is greatly changed. On the contrary, it can be seen that it is sufficient to adjust the total length a + b, particularly the length of the long side b, in order to obtain the desired reactance value.

  Specifically, the resistance L is adjusted by preparing an L-shaped probe 2 that is long for both a and b, and first adjusting the insertion amount a. When the adjustment of the resistance is completed, the reactance is adjusted by adjusting the length of the long side b (which can adjust the length of the total length a + b). At this time, the reactance at the frequency to be used may be adjusted to be substantially zero. Thereby, a notch antenna having desired resistance characteristics and reactance characteristics can be obtained.

  Here, the L-type probe 2 may be formed not by a linear conductor but by a thin film or a planar conductor. As shown in FIG. 4, when the probe 2 itself has a wide configuration in the plane of the notch 10, the effect of expanding the band can be obtained. Further, the probe 2 does not necessarily have to be arranged in the space of the notch 10, and may be arranged, for example, in the projection surface of the notch 10 viewed from the direction perpendicular to the surface of the conductive substrate 1 ( (See FIG. 5). Even in this case, the same effect as that in which the probe 2 is arranged in the notch 10 can be obtained. On the other hand, the width of the probe 2 itself can be easily brought close to the width of the notch 10, and the band expanding effect is further increased. In this case, in order to prevent contact between the conductive substrate 1 and the probe 2, an insulating thin film 4 may be disposed between them.

  An embodiment in which this notch antenna is used as an in-vehicle antenna will be described below. 6 and 7 show a form in which the heat ray pattern portion of the defogger 6 disposed for preventing and removing the fogging of the rear window 5 is used as a conductive substrate. In the form shown in FIG. 6, the L-type probe 2 and the power feeding unit 3 are provided by arranging the notch 10 inside the heat ray pattern portion of the defogger 6. In the form shown in FIG. 7, the notch 10 is arranged at one corner of the hot wire pattern portion of the defogger 6, and in order to secure the substrate area on the corner side of the pattern portion of the notch 10, A protrusion 16 having a length of about λ / 4 is disposed.

  FIG. 8 shows a form in which a notch antenna is arranged on the glass surface 7 of the front window or the side window. In this form, in order to ensure a driver | operator's visual field, the electroconductive board | substrate 1 located in the center side of the glass surface 7 is comprised by the metal frame 1a. In addition to the metal frame 1a, for example, it may be formed in a wire mesh shape or a punching metal shape. As long as it does not interfere with the field of view, it may be formed of a thin metal plate or a conductive transparent film.

  Further, as shown in FIGS. 9 to 11, the rear spoiler 8 and the body flange portion 75 on the back of the roof that protrudes outward from the glass surface 7 of the front window or the rear window (in an actual vehicle, glass is used). It is also possible to form it on the end or back surface of the rearview mirror 9).

At this time, as shown in FIG. 10, the notch 10 may have a crank shape having a turn. Also, the probe 2 itself may have a shape having a plurality of bent portions. Further, as shown in FIGS. 11A to 11C, in order to secure the substrate area on the corner side of the notch 10, the protrusion 17 having a length of about λ / 4 may be bent and arranged.
Since the notch antenna according to the present invention has such a high degree of freedom in shape and can be formed compactly, the degree of freedom in arrangement is improved.

  In-vehicle antennas must support various frequency bands such as radios, televisions, navigation devices, inter-vehicle communication devices, etc., but even when multiple antennas are placed, they ensure good transmission and reception characteristics and are inconspicuous positions It is possible to arrange.

  The notch antenna of the present invention can be used as a small antenna for various communication devices, receiving devices, etc. in addition to the vehicle-mounted antenna.

It is a front view which shows the basic composition of the notch antenna concerning this invention. It is a graph which shows the change of resistance and reactance when the total length of the L-type probe 2 is constant and the insertion amount is changed. It is a graph which shows the change of resistance and reactance when the insertion amount of the L-type probe 2 is constant and the length of the long side b is changed. It is a figure explaining the modification of the notch antenna of FIG. It is a figure explaining the modification of the notch antenna of FIG. 1, FIG. It is a figure which shows the form which has arrange | positioned the notch antenna concerning this invention to the rear window of a vehicle. It is a figure which shows another form which has arrange | positioned the notch antenna concerning this invention to the rear window of a vehicle. It is a figure which shows the form which has arrange | positioned the notch antenna concerning this invention to the front or side window of a vehicle. It is a figure which shows the form which has arrange | positioned the notch antenna concerning this invention to the rear spoiler of a vehicle. It is a figure which shows the form which has arrange | positioned the notch antenna concerning this invention in the glass back part of a vehicle. It is a figure which shows the form which has arrange | positioned the notch antenna concerning this invention to the rear-view mirror of a vehicle. It is a figure which shows the basic structure of the conventional notch antenna.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Conductive substrate, 1a ... Metal frame, 2 ... Probe, 3 ... Feeding part, 4 ... Thin film, 5 ... Rear window, 6 ... Defogger, 7 ... Glass surface, 8 ... Rear spoiler, 9 ... Room mirror, 10 ... Notch, 11 ... side wall, 12 ... side wall, 13 ... open end, 14 ... short-circuited end, 16 ... projecting part, 17 ... projecting part, 20 ... feeder, 21 ... short side, 22 ... bent part, 23 ... long side.

Claims (4)

An end of the conductive substrate has one end as an open end and the other end as a short-circuit end, and a notch having a side wall facing the open end and the short-circuit end is provided and electrically connected to one side of the side wall. In the notch antenna, which is configured by arranging a power feeding unit, arranging a power feeding probe in the projection plane of the notch when viewed from the direction perpendicular to the substrate surface of the substrate, and electrically connecting to the power feeding unit,
The power supply probe includes a portion extending from the power supply portion toward the opposite side wall, extending in parallel with the side wall surface of the opposite side wall through at least one bent portion. Notch antenna.   The notch antenna according to claim 1, wherein the power feeding unit is connected to an open end of the side wall.   The notch antenna according to claim 1, wherein the power feeding probe has a plurality of bent portions.   The notch antenna according to claim 1, wherein the notch has at least one bent portion.

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