JP2006033652A - Multi-band antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transmit/receive three or more frequencies including circularly polarized waves in a one power feeding point. <P>SOLUTION: An inside elliptic patch 200 and an outside ground plate 300 are disposed and formed on a front side surface of one dielectric substrate 100 and between these patch and ground plate, a slot ring 400 comprised of an outer edge and an inner edge thereof is formed. A microstrip line 500 is then disposed and formed on a rear surface side thereof. A current is made to flow to the microstrip line 500, thereby generating a circularly polarized wave of a first frequency from the inside elliptic patch 200, generating a magnetic flow in a portion of the slot ring 400 to generate a linearly polarized wave of a second frequency, and further generating a linearly polarized wave of a third frequency that is a higher harmonic wave of the first frequency in the inside elliptic patch 200. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multiband antenna, and more particularly to a multiband antenna that transmits and receives radio waves having a plurality of frequencies.

  As a conventional example of a multi-band antenna that transmits and receives radio waves of a plurality of frequencies with one antenna, one using a throttling as shown in FIG. 2 (first example), as shown in FIG. There are those in which the characteristics of the two frequency bands are ensured by the ratio of the dielectric constant of the dielectric to the patch and the dielectric constant of the dielectric to the outer patch (second example).

  In the example shown in FIG. 2 (first example), the radius r1 formed of a conductive thin plate is formed on the front surface of the dielectric substrate 100a having a predetermined size, thickness, and dielectric constant. An inner circular patch 250 is arranged, and a ground plate 300a made of a conductive thin plate cut into a circle with a radius r2 is arranged around the inner circular patch 250, and a slot ring 400a having a difference width between the radii r1 and r2 is formed therebetween. The microstrip line 500a is formed on the back surface of the dielectric substrate 100a, and the microstrip line 500a supplies the microstrip line 500a. When power is supplied from the microstrip line 500a while changing the frequency, the return loss is reduced in a plurality of frequency bands, and radio waves can be transmitted and received using these frequency bands (for example, see Non-Patent Document 1). ).

  The multiband antenna of this first example is dedicated to linearly polarized waves and cannot transmit / receive circularly polarized waves. Here, in order to generate circularly polarized waves, two linearly polarized waves having different phases may be generated in two orthogonal directions.

The second example shown in FIG. 3 aims at a dual-frequency circularly polarized antenna capable of supporting the GPS L1 and L2 bands, and each antenna element corresponding to both bands has a different dielectric constant. This is a patch antenna using the dielectric substrates 100b and 100c. In this antenna, as the L1 band, a four-sided inner patch 270 of a conductive thin plate is disposed on the front side surface of the dielectric substrate 100b having a dielectric constant ε _r1 , and as the L2 band, this is disposed outside the dielectric substrate 100b. A dielectric substrate 100c having a dielectric constant _εr2 of the same thickness is provided with a quadrilateral inner patch 270 and an outer patch 300b arranged on the outer surface in the same plane, and the dielectric substrates 100b and 100c. A base plate 550 is disposed on the back side of the. The feeding method is a coaxial feeding method from the back with respect to the feeding points 710 and 720 of both patches (see, for example, Non-Patent Document 2).
Hooman Tehrani, Kai Chang, "Multifrequency Operation of Microstrip-Fed Slot-Ring Antennas on Thin Low-Dielectric Permittivity Substrates", IEEE Transactino on Antennas and Propagation, vol.50, No.9, pp.1299-1308, September.2002 Nakanishi Seiichi, Saito Hiroshi, Uno Hiroyuki, Nagano Isamu, Yagitani Satoshi, Ishigaki Toshihiro, “Fundamental Study of Dual Frequency Circularly Polarized Patch Antennas”, IEICE Technical Report, AP2002-108, pp.41-44

In the first example, the multiband antenna according to the background art described above is cut out into a circular shape with a radius r2 around the circular inner circular patch 250 with a radius r1 on the front surface of the dielectric substrate 100a. Since a slot ring 400a having a difference width between radii r1 and r2 is formed between them, a circularly polarized wave is transmitted and received. In the second example in which circularly polarized waves can be transmitted and received, the quadrilateral shape is formed on the front surface of the quadrilateral dielectric substrate 100b having a dielectric constant ε _r1 for the L1 band. the inner patch 270 is disposed in, for the L2 band, by arranging the dielectric substrate 100c of the dielectric constant epsilon _r2 outside of the dielectric substrate 100b, the surface of its front side, and the outer is coplanar with inner patch 270 The outer patch 300b is arranged, and the feeding method is a coaxial feeding system from the back to the feeding points 710 and 720 of each patch. This multiband antenna can transmit and receive two frequencies in the L1 and L2 bands, but it can transmit and receive more than three and three frequencies. There is also a problem that it is not possible.

  In view of the problems of the background art described above, an object of the present invention is to transmit and receive circularly polarized waves by supplying power to only one feeding point, and to transmit and receive radio waves at three frequencies or more than three frequencies. It is to provide a multiband antenna that can be used.

The multiband antenna of the present invention is
A multiband antenna that transmits and receives multiple radio waves,
A dielectric substrate having a predetermined size, thickness, and dielectric constant;
An inner elliptic patch arranged and formed in an elliptical shape with a conductive thin plate on the front surface of the dielectric substrate,
Arranged on the outer surface of the inner elliptical patch on the front surface of the dielectric substrate;
Arrangement of the inner elliptical patch, a base plate cut into a circular shape centering on the formation center, and a slot ring between the edge of the circular hollowed portion and the outer edge of the inner elliptical patch,
A microstrip line arranged and formed at a predetermined position on the back surface of the dielectric substrate with respect to the inner elliptical patch;
Comprising
By passing a current through the microstrip line,
In the major axis direction and the minor axis direction of the inner elliptical patch, currents having different phases flow to generate circularly polarized waves at the first frequency,
By passing a current through the microstrip line,
A magnetic current is generated in the throttling portion, and the magnetic current generates a linearly polarized wave at a second frequency;
By passing a current through the microstrip line,
A harmonic current of the first frequency flows through the inner elliptical patch, and a linearly polarized wave is generated at a third frequency by the harmonic current.

  Further, the tip of the microstrip line is over the back side of the inner elliptical patch.

  In the present invention, an inner elliptical patch and a ground plane are arranged on the front surface of a single dielectric substrate, and a throttling between the outer edge and the inner edge is formed between them. And forming a microstrip line on the back side of the microstrip line to cause a current to flow through the microstrip line, thereby generating circular polarization at a first frequency from the inner elliptical patch, and a throttling portion Generating a magnetic current at a second frequency to generate a linearly polarized wave, and further causing the inner elliptical patch to generate a linearly polarized wave at a third frequency that is a harmonic of the first frequency. Since it has a structure and configuration, it is possible to transmit and receive circularly polarized waves by feeding from a single feeding point, and to transmit and receive radio waves of three frequencies or more than three frequencies. is there.

The best mode for carrying out the present invention is:
A multiband antenna that transmits and receives multiple radio waves,
A dielectric substrate having a predetermined size, thickness, and dielectric constant;
An inner elliptic patch arranged and formed in an elliptical shape with a conductive thin plate on the surface on the front side of this dielectric substrate,
Arranged and formed on the outer surface of the inner elliptical patch on the front surface of the dielectric substrate,
Arrangement of the inner elliptic patch, a ground plate cut into a circular shape centered on the formation center, and a slot ring between the edge of the portion cut into the circular shape and the outer edge of the inner elliptic patch,
A microstrip line disposed and formed at a predetermined position on the back surface of the dielectric substrate with respect to the inner elliptical patch;
Comprising
By passing a current through the microstrip line,
Currents of different phases flow in the major axis direction and minor axis direction of the inner elliptical patch to generate circularly polarized waves at the first frequency,
By passing a current through the microstrip line,
A magnetic current is generated in the throttling portion, and a linearly polarized wave is generated at the second frequency by the magnetic current,
By passing a current through the microstrip line,
A harmonic current corresponding to a frequency that is an integral multiple of the first frequency is passed through the inner elliptical patch, and linearly polarized waves are generated at the third frequency by the harmonic current.

  The tip of the microstrip line may be on the back side of the inner elliptical patch.

Next, Embodiment 1 of the present invention will be described with reference to the drawings.
1 is a plan view of a multiband antenna according to a first embodiment of the present invention, and a partial cross-sectional side view seen from two directions.
The multiband antenna according to the first embodiment includes a dielectric substrate 100 having a predetermined size, thickness, and dielectric constant, and a conductive thin plate (a conductive foil) on the front side surface of the dielectric substrate 100. The inner elliptical patch 200 arranged and formed in an elliptical shape,
The outer surface of the dielectric substrate 100 is arranged and formed outside the inner elliptical patch 200, and the inner elliptical patch 200 is arranged and formed into a circular shape having a center as a center (radius r). A ground plane 300 having a slot ring 400 between the edge of the circular hollowed portion and the outer edge of the inner oval patch 200;
A microstrip line 500 arranged and formed at a predetermined position on the back surface of the dielectric substrate 100 with respect to the inner elliptical patch 200;
A structure having
By passing a current through the microstrip line 500,
Currents with different phases flow in the major axis a direction and the minor axis b direction of the inner elliptic patch 200 to generate circularly polarized waves at the first frequency,
Also, by passing a current through the microstrip line 500,
A magnetic current is generated in the throttling 400, and this magnetic current generates a linearly polarized wave at the second frequency,
Furthermore, by passing a current through the microstrip line 500,
A harmonic current of the first frequency flows through the inner elliptical patch 200, and a linearly polarized wave is generated at the third frequency by the harmonic current.
It has a structure and configuration.

  The tip of the microstrip line 500 is on the back side of the inner elliptical patch 200, and the arrangement of the microstrip line 500 relative to the inner elliptical patch 200, for example, the dimensions d1 and d2 shown in FIG. By setting, the current flowing in the major axis direction and minor axis direction of the inner elliptical patch 200 is adjusted, and reflection loss of radio waves transmitted and received is reduced.

Next, operations for generating each frequency of the multiband antenna in the first embodiment will be described.
First, generally speaking, this multiband antenna is an antenna having an elliptical patch part (200) and a slot part (400). In the patch section, radiation is generated by the current flowing through the patch and the magnetic field generated by the current (Ampere's law), so the current is directly caused by the radiated electromagnetic field. In the slot portion, radiation is generated (Faraday's law) by an electric field and a magnetic current generated by the electric field. Therefore, the magnetic current is directly caused. Therefore, the first frequency and the third frequency will mainly describe the current, and the second frequency will mainly describe the magnetic current.

Next, each of these frequencies will be described.
First, at the first frequency, when current flows on the microstrip line (500) on the back surface of the substrate (100), electromagnetic coupling occurs between the microstrip line and the elliptical patch, and current flows on the elliptical patch. Flowing. Here, since the lengths of the major axis direction (a) and the minor axis direction (b) are different on the elliptical patch, currents having different phases flow in two orthogonal directions. By adjusting (amplitude etc.) these two currents in the major axis direction and the minor axis direction, circular polarization occurs at the first frequency.

  Next, at the second frequency, a current flows on the microstrip line (500) on the back surface of the substrate, whereby a current flows on the elliptical patch. At this time, an electric field is generated between the elliptical patch and the ground plane (the outer conductor from the elliptical patch on the substrate surface, that is, the ground plane 300), and a ring-shaped magnetic current is generated on the slot (400). . Since this magnetic current resonates in the direction along the slot, linearly polarized waves are generated.

  The state of current on the elliptical patch at the second frequency will be described. Current flows on the elliptical patch due to electromagnetic field coupling. However, the radiation at the second frequency is due to the shape of the slot and not directly due to the state of the current flowing on the elliptical patch. Therefore, in the slot antenna, it is not necessary to consider the current state when the state of the magnetic current caused directly is known. In consideration, a current that generates a magnetic current along the ring-shaped slot flows.

  Here, the magnetic current generated on the slot is in a complementary relationship with the current flowing on the ring conductor having a circular outer side and an elliptical inner side. Not considering the current on the elliptical patch is the same as focusing on the current on the conductor instead of focusing on the magnetic current inside the ring in the ring antenna (loop antenna) which is the complementary relationship of the slot antenna. It can be said.

  Subsequently, at the third frequency, a current flows on the elliptical patch as in the first frequency principle. In this case, a harmonic current having a frequency that is an integral multiple of the first frequency flows on the elliptical patch. The third-frequency radiation is radiation from the harmonic current, and the radiation electromagnetic field generated by the second-order harmonic current is weak in the antenna zenith direction and generates linear polarization instead of circular polarization.

Based on the above principle, a single-feeding point is a multiband antenna capable of transmitting and receiving three frequencies: circular polarization at the first frequency, linear polarization at the second frequency, and linear polarization at the third polarization.
In FIG. 1, a reflector 600 is shown, but this reflector 600 is intended to prevent leakage of radio waves to the back side and does not directly affect the above three frequency characteristics. Absent.

It is the top view of the multiband antenna in Example 1 of this invention, and the partial cross section side view seen from 2 directions. It is the top view which shows the 1st example of the multiband antenna in background art, and the partial cross section side view seen from 2 directions. It is the top view which shows the 2nd example of the multiband antenna in background art, and the partial cross section side view seen from 2 directions.

Explanation of symbols

100, 100a to 100c Dielectric substrate 200 Inner elliptical patch 250 Inner circular patch 270 Inner patch 300, 300a Ground plate 300b Outer patch 400, 400a Throttling 500, 500a Microstrip line 550 Ground plate 600 Reflector plate 710, 720 Feed point

Claims (2)

A multiband antenna that transmits and receives multiple radio waves,
A dielectric substrate having a predetermined size, thickness, and dielectric constant;
An inner elliptic patch arranged and formed in an elliptical shape with a conductive thin plate on the front surface of the dielectric substrate,
Arranged on the outer surface of the inner elliptical patch on the front surface of the dielectric substrate;
Arrangement of the inner elliptical patch, a base plate cut into a circular shape centering on the formation center, and a slot ring between the edge of the circular hollowed portion and the outer edge of the inner elliptical patch,
A microstrip line arranged and formed at a predetermined position on the back surface of the dielectric substrate with respect to the inner elliptical patch;
Comprising
By passing a current through the microstrip line,
In the major axis direction and the minor axis direction of the inner elliptical patch, currents having different phases flow to generate circularly polarized waves at the first frequency,
By passing a current through the microstrip line,
A magnetic current is generated in the throttling portion, and the magnetic current generates a linearly polarized wave at a second frequency;
By passing a current through the microstrip line,
A harmonic current of the first frequency flows through the inner elliptical patch, and the harmonic current generates a linearly polarized wave at a third frequency.
A multiband antenna characterized by that. The multiband antenna according to claim 1, wherein a tip of the microstrip line is on a back side of the inner elliptical patch.

Images