JP6817636B2 - Circularly polarized antenna - Google Patents

Description

The present invention relates to a circularly polarized antenna, and more particularly to a circularly polarized antenna capable of switching between left-handed rotation and right-handed rotation.

Conventionally, as this type of circularly polarized antenna, a T-type conductor element having a length from an open end to another open end having a wavelength of about half, and a connection point between a square conductor base plate and a T-type conductor element. Two quarter-wavelength L-shaped objects connected to the feeding point provided in the above and the connection point of the T-shaped conductor element when viewed from the center of the conductor base plate at an angle difference of ± 90 degrees. Proposed ones include a pole conductor element and two switches for switching between connection and non-connection of the conductor base plate and each L-shaped monopole conductor element (see, for example, Patent Document 1). In this antenna, one of the two switches is turned on and the other is turned off, and conversely, one is turned off and the other is turned on to switch between left-handed rotation and right-handed rotation.

Japanese Unexamined Patent Publication No. 2007-335899

However, in the above-mentioned circularly polarized antenna, even if the left-handed rotation and the right-handed rotation can be easily switched, the directivity and loss of the antenna, the width of the band, and the like are unknown. In communication by circularly polarized waves, it is necessary not only to easily switch the polarized waves but also to have high directivity, and it is also desired to reduce the size and weight. High gain and wide bandwidth are also desired.

A main object of the circularly polarized antenna of the present invention is to provide an antenna having high directivity and easy switching of circularly polarized waves.

The circularly polarized antenna of the present invention has adopted the following means in order to achieve the above-mentioned main object.

The circularly polarized antenna of the present invention
A circularly polarized antenna that can switch between left-handed and right-handed
A ladder-shaped first antenna formed of a conductive material and having two struts arranged in parallel, both ends of the two struts, and a plurality of semi-annular treads attached between them. Members and
With the same second antenna member as the first antenna member,
Feeding point and
Conductive base plate and
With
The first antenna member and the second antenna member so that the plurality of treads of the first antenna member and the plurality of treads of the second antenna member form an annular shape with a slight gap. And place and
The conductive main plate is arranged at one end of the first antenna member and the second antenna member with a slight gap.
In addition
A first switch connected to one corner of the one end of the first antenna member and one terminal of the feeding point.
A second switch connected to the other corner of the one end of the first antenna member and the other terminal of the feeding point.
A third switch connected to one corner of the one end of the second antenna member and the other terminal of the feeding point.
A fourth switch connected to the other corner of the one end of the second antenna member and one terminal of the feeding point.
The gist is to prepare.

In the circularly polarized antenna of the present invention, the two first antenna members and the second antenna member having the same ladder shape face each other with a slight gap so that the plurality of treads face each other to form an annular shape. The conductive main plate is arranged at one end of the first antenna member and the second antenna member with a slight gap. Therefore, in the circularly polarized wave antenna of the present invention, the two antenna members have a cylindrical shape as a whole. From this shape, the inventors refer to the circularly polarized antenna of the present invention as a "laddering antenna". Further, both corners of one end of the first antenna member and the second antenna member and both terminals of the feeding point are connected by four switches (first switch to fourth switch), respectively. In the circularly polarized antenna of the present invention, the first switch is turned on, the second switch is turned off, the third switch is turned on, the fourth switch is turned off, and conversely, the first switch is turned off, the second switch is turned on, and the second switch is turned on. By turning off the 3rd switch and turning on the 4th switch, the left-handed rotation and the right-handed rotation are switched. The circularly polarized antenna of the present invention transmits and receives circularly polarized waves in the direction of the central axis of a cylindrical shape. At this time, a strong rotating electric field is generated in the annular treads facing each other, and a strong rotating electric field is also generated in the annular facing treads at the end opposite to the feeding point. Therefore, the directivity is high and the gain is high. Of course, it is possible to easily switch between left-handed and right-handed. In the circularly polarized antenna of the present invention, when the housing such as a member on which the antenna is installed and other parts are conductive, the housing and other parts can fulfill the function of the "conductive main plate". , The housing and other parts are regarded as a "conductive base plate", and it is not necessary to separately provide a "conductive base plate".

In the circularly polarized antenna of the present invention, it is preferable that the plurality of treads are an even number of treads. In particular, the number of treads is preferably 4 or 6.

In the circularly polarized antenna of the present invention, the plurality of stepped portions may be formed in a semi-annular shape with a radius based on the length obtained by dividing the wavelength of the target electromagnetic wave by 2π. In this case, the radius is preferably in the range of 30% long and short length based on the length obtained by dividing the wavelength of the target electromagnetic wave by 2π. By changing the radius of multiple treads within the range of 30% of the length from the reference in this way, the transmitting antenna of the signal (reflected power) returned without being transmitted when transmitting from the transmitting antenna. The specific band can be increased with respect to the S11 parameter shown as a ratio to the signal fed to the antenna (input power to the antenna) or the axial ratio indicating the degree of ellipse of elliptically polarized light.

In the circularly polarized antenna of the present invention, the plurality of treads may be arranged at intervals within a length range based on the length of a quarter wavelength of the target electromagnetic wave. In this case, the distance between the stepping portions is preferably within the range of 30% long and short lengths based on the length of a quarter wavelength of the target electromagnetic wave. If the spacing between multiple treads is changed within the range of 30% long and short with reference to the length of a quarter wavelength of the target electromagnetic wave, the specific band can be increased with respect to the S11 parameter or axial ratio. it can.

It is a block diagram which shows the outline of the structure of the ladder ring antenna 20 as one Example of this invention. It is explanatory drawing which shows the simulation result with respect to the directionality in the left-handed circularly polarized wave mode. It is explanatory drawing which shows the simulation result about the relationship between a gain (gain) and a frequency in a left-handed circularly polarized wave mode. It is a graph which shows the simulation result of the relationship between the interval d of the stepping portion 34a-34d, 44a-44d, the frequency of an electromagnetic wave, and the axial ratio. It is a graph which shows the simulation result of the relationship between the radius R of the stepping part 34a-34d, 44a-44d, the frequency of an electromagnetic wave, and the S11 parameter. It is explanatory drawing which shows the simulation result of the relationship between the frequency and the axial ratio of the electromagnetic wave in the left-handed circularly polarized wave mode of the ladder ring antenna 20 of a reference size. It is explanatory drawing which shows the simulation result of the relationship between the frequency of the electromagnetic wave and the S11 parameter in the left-handed circularly polarized wave mode of the ladder ring antenna 20 of a reference size. It is explanatory drawing which shows the simulation result with respect to the directionality at the time of the left-handed circularly polarized wave mode of the ladder ring antenna 20 of a reference size. It is explanatory drawing which shows the simulation result of the relationship between the frequency and the axial ratio of the electromagnetic wave in the left-handed circularly polarized wave mode of a 2/3 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result of the relationship between the frequency of the electromagnetic wave and the S11 parameter in the left-handed circularly polarized wave mode of a 2/3 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result with respect to the directionality at the time of a left-handed circularly polarized wave mode of a 2/3 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result of the relationship between the frequency and the axial ratio of the electromagnetic wave in the left-handed circularly polarized wave mode of a 1/2 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result of the relationship between the frequency of the electromagnetic wave and the S11 parameter in the left-handed circularly polarized wave mode of a 1/2 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result with respect to the directionality at the time of the left-handed circularly polarized wave mode of the ladder ring antenna 20 of 1/2 size. It is explanatory drawing which shows the simulation result of the relationship between the frequency and the axial ratio of the electromagnetic wave in the left-handed circularly polarized wave mode of the ladder ring antenna 20 of 1/3 size. It is explanatory drawing which shows the simulation result of the relationship between the frequency of the electromagnetic wave and the S11 parameter in the left-handed circularly polarized wave mode of the ladder ring antenna 20 of 1/3 size. It is explanatory drawing which shows the simulation result with respect to the directionality at the time of the left-handed circularly polarized wave mode of the ladder ring antenna 20 of 1/3 size. It is explanatory drawing which shows the simulation result of the relationship between the frequency and the axial ratio of the electromagnetic wave in the left-handed circularly polarized wave mode of a 1/4 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result of the relationship between the frequency of the electromagnetic wave and the S11 parameter in the left-handed circularly polarized wave mode of a 1/4 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result with respect to the directionality at the time of a left-handed circularly polarized wave mode of a 1/4 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result of the relationship between the frequency and the axial ratio of the electromagnetic wave in the left-handed circularly polarized wave mode of the ladder ring antenna 20 of 1/10 size. It is explanatory drawing which shows the simulation result of the relationship between the frequency of the electromagnetic wave and the S11 parameter in the left-handed circularly polarized wave mode of the ladder ring antenna 20 of 1/10 size. It is explanatory drawing which shows the simulation result with respect to the directionality at the time of the left-handed circularly polarized wave mode of the ladder ring antenna 20 of 1/10 size. It is explanatory drawing which shows the simulation result of the relationship between the frequency and the axial ratio of the electromagnetic wave in the left-handed circularly polarized wave mode of the rudder ring antenna 20 of 1/15 size. It is explanatory drawing which shows the simulation result of the relationship between the frequency of the electromagnetic wave and the S11 parameter in the left-handed circularly polarized wave mode of a rudder ring antenna 20 of 1/15 size. It is explanatory drawing which shows the simulation result with respect to the directionality at the time of a left-handed circularly polarized wave mode of a ladder ring antenna 20 of 1/15 size. It is explanatory drawing which shows the simulation result of the relationship between the frequency and the axial ratio of the electromagnetic wave in the left-handed circularly polarized wave mode of a 1/20 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result of the relationship between the frequency of the electromagnetic wave and the S11 parameter in the left-handed circularly polarized wave mode of a 1/20 size ladder ring antenna 20. It is explanatory drawing which shows the simulation result with respect to the direction | direction of the rudder ring antenna 20 of 1/20 size in the left-handed circularly polarized wave mode.

Next, a mode for carrying out the present invention will be described with reference to examples.

FIG. 1 is a configuration diagram showing an outline of the configuration of a ladder ring antenna 20 as an embodiment of the present invention. As shown in the figure, the rudder ring antenna 20 of the embodiment is formed of a first antenna member 30 formed of a conductive material (aluminum, titanium-nickel alloy, metal material such as stainless steel, etc.) and a conductive material. It is composed of a second antenna member 40, a feeding point 50, a conductive base plate 60, and four diodes D1 to D4 that function as switches.

The first antenna member 30 includes two support columns 32a and 32b arranged in parallel and four stepping portions 34a to 34d formed in a semi-annular shape and connected to the two support columns 32a and 32b at substantially equal intervals. It is formed in the shape of a ladder having. The stepping portions 34a to 34d are formed so that the radius R is a value obtained by dividing the wavelength of the target electromagnetic wave by 2π, and the interval d is arranged so as to be a quarter of the wavelength of the target electromagnetic wave. There is.

The second antenna member 40 has two strut portions 42a and 42b arranged in parallel and four tread portions 44a to 44d formed in a semi-annular shape and connected to the two strut portions 42a and 42b at substantially equal intervals. Is formed in the same shape as the first antenna member 30. The first antenna member 30 and the second antenna member 40 are arranged so that the four tread portions 34a to 34d and the four tread portions 44a to 44d face each other in an annular shape with a slight gap. There is. The shape including the first antenna member 30 and the second antenna member 40 is referred to by the inventors as a "ladder ring" shape.

The conductive base plate 60 is formed in a thin plate shape by a conductive material, and is arranged at one end of the first antenna member 30 and the second antenna member 40 with a slight gap. When the housing such as the member on which the ladder ring antenna 20 of the embodiment is installed and other parts are conductive, the conductive base plate 60 can fulfill its function. The housing and other parts can be regarded as the conductive main plate 60.

The connection portion between the support column portion 32a and the tread portion 34d of the first antenna member 30 and one terminal 52a of the feeding point 50 are connected by a diode D1 in the forward direction from the connection portion to the terminal 52a. .. The connection portion between the strut portion 32b and the tread portion 34d of the first antenna member 30 and the other terminal 52b of the feeding point 50 are connected by a diode D2 in the forward direction from the connection portion to the terminal 52b. .. The connecting portion between the strut portion 42a and the stepping portion 44d of the second antenna member 40 and the other terminal 52b of the feeding point 50 are connected by a diode D3 in the forward direction from the terminal 52b to the connecting portion. .. The connection portion between the support portion 42b and the tread portion 44d of the second antenna member 40 and one terminal 52a of the feeding point 50 are connected by a diode D4 in which the direction of the connection portion is in the forward direction from the terminal 52a. ..

The rudder ring antenna 20 configured in this way turns off the diodes D1 and D3 by applying an appropriate DC bias, and turns on the diodes D2 and D4 to cause left-handed circular polarization (LHCP). It functions as an antenna, and conversely, it functions as an antenna for right hand circular polarization (RHCP) by turning on the diodes D1 and D3 and turning off the diodes D2 and D4.

Next, the performance of the ladder ring antenna 20 of the embodiment will be described. FIG. 2 is an explanatory diagram showing the simulation results for the directionality in the left-handed circularly polarized wave mode, and FIG. 3 is an explanatory diagram showing the simulation results for the relationship between the gain and the frequency in the left-handed circularly polarized wave mode. .. In FIG. 2, the solid line is the gain for left-handed circularly polarized wave (LHCP), and the broken line is the gain for right-handed circularly polarized wave (RHCP). “0 °” in FIG. 2 indicates the upward direction of the central axis with respect to the plane of the annulus formed by the treads 34a and 44a in FIG. 1, and “−90 °” and “90 °” indicate the horizontal direction in FIG. Shown. In the ladder ring antenna 20 used in this simulation, the step portions 34a to 34d and 44a to 44d are formed with a radius of 15 mm and each interval d is 25 mm in order to use an electromagnetic wave having a frequency of 3 GHz as the target electromagnetic wave. Was used. As shown in FIG. 2, it can be seen that the ladder ring antenna 20 of the embodiment has a strong directivity in the “0 °” direction in the left-handed circularly polarized wave. Further, as shown in FIG. 3, the ladder ring antenna 20 of the embodiment shows a high gain at a wide frequency, and the gain in the “0 °” direction at 3 GHz is 9.79 dBi. From these facts, it can be seen that the ladder ring antenna 20 of the embodiment is an antenna that is easy to switch circularly polarized waves, has high directivity in the "0 °" direction, and has a wide band.

FIG. 4 is a graph showing a simulation result of the relationship between the distance d between the stepping portions 34a to 34d and 44a to 44d and the frequency and axial ratio of the electromagnetic wave. As the ladder ring antenna 20 used in this simulation, the target electromagnetic wave is an electromagnetic wave having a frequency of 3 GHz, each step portion 34a to 34d, 44a to 44d is formed with a radius of 15 mm, and the interval d is 23 mm to 27 mm centered on 25 mm. The ones arranged by changing the frequency by 1 mm were used. According to the simulation results, when the interval d is 25 mm, the axial ratio is close to 0 dB at 2.9 GHz, and the specific band is 15%. This means that the ladder ring antenna 20 of the embodiment has a wide band and is an excellent antenna. Further, it can be seen that as the interval d becomes larger, the frequency shifts to the lower frequency side. Based on these facts, a part of the distance d between the stepping portions 34a to 34d and 44a to 44d was set in both the long and short directions from the length (25 mm in the case of 3 GHz) based on a quarter of the wavelength of the target electromagnetic wave. It can be seen that the band can be widened by setting the length. It is preferable that the variation of the interval d between the stepping portions 34a to 34d and 44a to 44d is within a range of 30% in length centered on a quarter of the wavelength of the target electromagnetic wave. Conceivable.

FIG. 5 is a graph showing the simulation results of the relationship between the radii R of the stepping portions 34a to 34d and 44a to 44d, the frequency of the electromagnetic wave, and the S11 parameter. The ladder ring antenna 20 used in this simulation is an electromagnetic wave having a frequency of 3 GHz as the target electromagnetic wave, and each step portion 34a to 34d and 44a to 44d is formed by changing 1 mm from 13 mm to 17 mm with a radius of 15 mm as the center. Then, the one in which the interval d was arranged at 25 mm was used. According to the simulation result, the specific band is 16.7% when the radius R is 15 mm. This means that the ladder ring antenna 20 of the embodiment is a wide band antenna. Further, it can be seen that as the radius R increases, the frequency shifts to the low frequency side. Based on these facts, the radius R of a part of the stepping portions 34a to 34d and 44a to 44d should be divided from the length obtained by dividing the wavelength of the target electromagnetic wave by 2π (15 mm in the case of 3 GHz) to the length divided in both the long and short directions. It can be seen that the band can be widened. It is considered that the variation of the radius R of the stepping portions 34a to 34d and 44a to 44d is preferably within the range of 30% in length centered on the length obtained by dividing the wavelength of the target electromagnetic wave by 2π.

In the ladder ring antenna 20 of the embodiment described above, the first antenna member 30 formed in a ladder shape by the two strut portions 32a and 32b and the four tread portions 34a to 34d formed in a semi-annular shape, and the first antenna member 30 The second antenna member 40 formed in the same shape as the one antenna member 30 is formed into an annular shape in which the four step ladders 34a to 34d and the four stepladder portions 44a to 44d face each other with a slight gap. The conductive main plate 60 is arranged at one end of the first antenna member 30 and the second antenna member 40 (the end on the feeding point 50 side) with a slight gap. Then, both corners (connection portions) of the lower end of FIG. 1 of the first antenna member 30 and the second antenna member 40 are connected to the terminals 52a and 52b of the feeding point 50 by four diodes D1 to D4. In the ladder ring antenna 20 of the embodiment, the left-handed circularly polarized wave mode and the right-handed circularly polarized wave mode can be switched only by switching the diodes D1 to D4 on and off. Further, the ladder ring antenna 20 of the embodiment has a strong directivity in the "0 °" direction (the direction of the central axis of the cylindrical shape) and can have a high gain. Further, the ladder ring antenna 20 of the embodiment can be a wide band antenna.

In the ladder ring antenna 20 of the embodiment, since the simulation was performed using an electromagnetic wave having a frequency of 3 GHz as the target electromagnetic wave, the ladder ring antenna 20 has a radius R of each step portion 34a to 34d and 44a to 44d of 15 mm and an interval d. The antenna having a radius of 25 mm was used. However, if the frequency of the target electromagnetic wave is different, the radius R and the interval d of each step portion 34a to 34d and 44a to 44d are also the corresponding radius (value obtained by dividing the wavelength of the target electromagnetic wave by 2π) and the interval (of the target electromagnetic wave). It may be a value of 1/4 of the wavelength). Hereinafter, the relationship between the size of the ladder ring antenna 20 of the embodiment and the frequency of the symmetric electromagnetic wave will be described.

As the reference size of the rudder ring antenna 20 of the embodiment, it is assumed that an electromagnetic wave having a frequency of 3 GHz is the target electromagnetic wave, and the radius R of the four-stage stepped portions 34a to 34d and 44a to 44d is 15 mm, and the stepped portion 34a to The distance d between 34d and 44a to 44d is 25 mm, the radius R0 of the conductive base plate 60 is 60 mm, the gap α between the first antenna member 30 and the second antenna member 40 is 5.2 mm, the first antenna member 30 and the second antenna The distance h between the member 40 and the conductive base plate 60 was 1 mm, and the width s of the conducting wire was 1 mm. The simulation result of the relationship between the electromagnetic wave frequency and the axial ratio in the left-handed circularly polarized wave mode of the reference size ladder ring antenna 20 is shown in FIG. 6, and the simulation result of the relationship between the electromagnetic wave frequency and the S11 parameter is shown in FIG. The simulation result for sex is shown in FIG. The white arrows in FIG. 7 indicate the frequencies of the target electromagnetic waves. It can be seen that the reference size ladder ring antenna 20 has a high gain with respect to an electromagnetic wave of 3 GHz as shown in FIGS. 6 and 7, and as shown in FIG. 8, it is found to have a high gain in the “0 °” direction (center of the cylindrical shape). It can be seen that it has a strong directivity (in the axial direction). From this, it can be seen that the reference size ladder ring antenna 20 can set 3 GHz as the frequency of the target electromagnetic wave.

The 2/3 size ladder ring antenna 20, which is 2/3 of the standard size, has a radius R of 10 mm, an interval d of 50/3 mm, a radius R0 of 40 mm, a gap α of 5.2 mm, an interval h of 1 mm, and a width s. Was 1 mm. Fig. 9 shows the simulation result of the relationship between the electromagnetic wave frequency and the axial ratio in the left-handed circularly polarized wave mode of the 2/3 size ladder ring antenna 20, and Fig. 10 shows the simulation result of the relationship between the electromagnetic wave frequency and the S11 parameter. The simulation result for the directionality is shown in FIG. The white arrows in FIG. 10 indicate the frequency of the target electromagnetic wave. It was found that the 2/3 size ladder ring antenna 20 had a high gain with respect to an electromagnetic wave of 4.4 GHz as shown in FIGS. 9 and 10, and as shown in FIG. 11, it was found to have a high gain in the “0 °” direction (as shown in FIG. 11). It can be seen that it has a strong directivity (in the direction of the central axis of the cylindrical shape). From this, it can be seen that the ladder ring antenna 20 having a size of 2/3 can set 4.4 GHz as the frequency of the target electromagnetic wave.

The 1/2 size ladder ring antenna 20, which is 1/2 of the standard size, has a radius R of 7.5 mm, an interval d of 12.5 mm, a radius R0 of 30 mm, a gap α of 5.2 mm, and an interval h of 1 mm. The width s was 1 mm. FIG. 12 shows the simulation result of the relationship between the electromagnetic wave frequency and the axial ratio in the left-handed circularly polarized wave mode of the 1/2 size ladder ring antenna 20, and FIG. 13 shows the simulation result of the relationship between the electromagnetic wave frequency and the S11 parameter. The simulation result for the directionality is shown in FIG. The white arrows in FIG. 13 indicate the frequency of the target electromagnetic wave. It was found that the 1/2 size ladder ring antenna 20 had a high gain with respect to an electromagnetic wave of 5.6 GHz as shown in FIGS. 12 and 13, and as shown in FIG. 14, it was found to have a high gain in the “0 °” direction (as shown in FIG. It can be seen that it has a strong directivity (in the direction of the central axis of the cylindrical shape). From this, it can be seen that the 1/2 size ladder ring antenna 20 can set 5.6 GHz as the frequency of the target electromagnetic wave.

The 1/3 size ladder ring antenna 20, which is 1/3 of the standard size, has a radius R of 5 mm, an interval d of 25/3 mm, a radius R0 of 20 mm, a gap α of 5.2 mm, an interval h of 1 mm, and a width s. Was 1 mm. FIG. 15 shows the simulation result of the relationship between the electromagnetic wave frequency and the axial ratio in the left-handed circularly polarized wave mode of the 1/3 size ladder ring antenna 20, and FIG. 16 shows the simulation result of the relationship between the electromagnetic wave frequency and the S11 parameter. The simulation result for the directionality is shown in FIG. The white arrows in FIG. 16 indicate the frequency of the target electromagnetic wave. It was found that the 1/3 size ladder ring antenna 20 had a high gain with respect to an electromagnetic wave of 7.5 GHz as shown in FIGS. 15 and 16, and as shown in FIG. 17, it was found to have a high gain in the “0 °” direction (as shown in FIG. 17). It can be seen that it has a strong directivity (in the direction of the central axis of the cylindrical shape). From this, it can be seen that the ladder ring antenna 20 of 1/3 size can set 7.5 GHz as the frequency of the target electromagnetic wave.

The 1/4 size ladder ring antenna 20, which is 1/4 of the standard size, has a radius R of 3.75 mm, an interval d of 6.25 mm, a radius R0 of 15 mm, a gap α of 5.2 mm, and an interval h of 1 mm. The width s was 1 mm. FIG. 18 shows the simulation result of the relationship between the electromagnetic wave frequency and the axial ratio in the left-handed circularly polarized wave mode of the 1/4 size ladder ring antenna 20, and FIG. 19 shows the simulation result of the relationship between the electromagnetic wave frequency and the S11 parameter. The simulation result for the directionality is shown in FIG. The white arrows in FIG. 19 indicate the frequencies of the target electromagnetic waves. It was found that the 1/4 size ladder ring antenna 20 had a high gain with respect to an electromagnetic wave of 9.8 GHz as shown in FIGS. 18 and 19, and as shown in FIG. 20, it was found to have a high gain in the “0 °” direction (as shown in FIG. 20). It can be seen that it has a strong directivity (in the direction of the central axis of the cylindrical shape). From this, it can be seen that the 1/4 size ladder ring antenna 20 can set the frequency of the target electromagnetic wave to 9.8 GHz.

The 1/10 size ladder ring antenna 20, which is 1/10 of the standard size, has a radius R of 1.5 mm, an interval d of 2.5 mm, a radius R0 of 6 mm, a gap α of 1.3 mm, and an interval h of 0. The width was 3 mm and the width s was 0.3 mm. FIG. 21 shows the simulation result of the relationship between the electromagnetic wave frequency and the axial ratio in the left-handed circularly polarized wave mode of the 1/10 size ladder ring antenna 20, and FIG. 22 shows the simulation result of the relationship between the electromagnetic wave frequency and the S11 parameter. The simulation result for the directionality is shown in FIG. The white arrows in FIG. 22 indicate the frequencies of the target electromagnetic waves. It was found that the 1/10 size ladder ring antenna 20 had a relatively high gain with respect to an electromagnetic wave of 21.1 GHz as shown in FIGS. 21 and 22, and as shown in FIG. 23, it was “0 °”. It can be seen that it has a certain degree of directivity in the direction (the direction of the central axis of the cylindrical shape). From this, it can be seen that the ladder ring antenna 20 of 1/10 size can set 21.1 GHz as the frequency of the target electromagnetic wave.

The 1/15 size ladder ring antenna 20, which is 1/15 of the standard size, has a radius R of 1 mm, an interval d of 5/3 mm, a radius R0 of 4 mm, a gap α of 1.04 mm, and an interval h of 0.2 mm. The width s was 0.2 mm. FIG. 24 shows a simulation result of the relationship between the frequency and the axial ratio of the electromagnetic wave in the left-handed circularly polarized wave mode of the 1/15 size ladder ring antenna 20, and FIG. 25 shows the simulation result of the relationship between the electromagnetic wave frequency and the S11 parameter. , The simulation result for the directionality is shown in FIG. The white arrows in FIG. 25 indicate the frequency of the target electromagnetic wave. It was found that the 1/15 size ladder ring antenna 20 had a relatively high gain with respect to an electromagnetic wave of 26 GHz as shown in FIGS. 24 and 25, and as shown in FIG. 26, it was found to have a relatively high gain in the “0 °” direction (as shown in FIG. 26). It can be seen that it has a certain degree of strong directivity (in the direction of the central axis of the cylindrical shape). From this, it can be seen that the frequency of the target electromagnetic wave of the 1/15 size ladder ring antenna 20 is 26 GHz.

The 1/20 size ladder ring antenna 20, which is 1/20 of the standard size, has a radius R of 0.75 mm, an interval d of 1.25 mm, a radius R0 of 3 mm, a gap α of 0.6 mm, and an interval h of 0. The width was 1 mm and the width s was 0.1 mm. FIG. 27 shows the simulation result of the relationship between the electromagnetic wave frequency and the axial ratio in the left-handed circularly polarized wave mode of the 1/20 size ladder ring antenna 20, and FIG. 28 shows the simulation result of the relationship between the electromagnetic wave frequency and the S11 parameter. , The simulation result for the directionality is shown in FIG. The white arrows in FIG. 28 indicate the frequencies of the target electromagnetic waves. It was found that the 1/20 size ladder ring antenna 20 had a relatively high gain with respect to an electromagnetic wave of 34.7 GHz as shown in FIGS. 27 and 28, and as shown in FIG. 29, “0 °”. It can be seen that it has a certain degree of directivity in the direction (the direction of the central axis of the cylindrical shape). From this, it can be seen that the frequency of the target electromagnetic wave of the 1/15 size ladder ring antenna 20 is 34.7 GHz.

From the above description, it can be seen that the rudder ring antenna 20 can set the frequency of the electromagnetic wave substantially inversely proportional to the size as the target electromagnetic wave by changing the size. That is, the radius R of the stepping portions 34a to 34d and 44a to 44d is preferably a length obtained by dividing the wavelength of the target electromagnetic wave by 2π, and the interval d between the stepping portions 34a to 34d and 44a to 44d is 4 of the target electromagnetic wave. It turns out that a one-third wavelength length is suitable.

In the ladder ring antenna 20 of the embodiment, four step portions 34a to 34d and 44a to 44d are used to form a four-stage ladder ring shape, but six or eight step portions are used to form a six-stage or eight-stage ladder ring shape. The ladder ring shape may be any number of steps as long as the ladder ring shape has an even number of steps.

In the ladder ring antenna 20 of the embodiment, four diodes D1 to D4 are used as the four switches, but a switching element such as a field effect transistor (FET) may be used as long as it can be turned on and off.

Although the embodiments for carrying out the present invention have been described above with reference to examples, the present invention is not limited to these examples, and various embodiments are used without departing from the gist of the present invention. Of course, it can be done.

The present invention can be used in the manufacturing industry of circularly polarized antennas and the like.

Claims (4)

A circularly polarized antenna that can switch between left-handed and right-handed
A ladder-shaped first antenna formed of a conductive material and having two struts arranged in parallel, both ends of the two struts, and a plurality of semi-annular treads attached between them. Members and
With the same second antenna member as the first antenna member,
Feeding point and
Conductive base plate and
With
The first antenna member and the second antenna member so that the plurality of treads of the first antenna member and the plurality of treads of the second antenna member form an annular shape with a slight gap. And place and
The conductive main plate is arranged at one end of the first antenna member and the second antenna member with a slight gap.
In addition
A first switch connected to one corner of the one end of the first antenna member and one terminal of the feeding point.
A second switch connected to the other corner of the one end of the first antenna member and the other terminal of the feeding point.
A third switch connected to one corner of the one end of the second antenna member and the other terminal of the feeding point.
A fourth switch connected to the other corner of the one end of the second antenna member and one terminal of the feeding point.
A circularly polarized antenna equipped with. The circularly polarized antenna according to claim 1.
The plurality of treads are an even number of treads.
Circularly polarized antenna. The circularly polarized antenna according to claim 1 or 2.
The plurality of treads are formed in a semi-annular shape with a radius based on the length obtained by dividing the wavelength of the target electromagnetic wave by 2π.
Circularly polarized antenna. The circularly polarized antenna according to any one of claims 1 to 3.
The plurality of stepping portions are arranged at intervals within a length range based on the length of a quarter wavelength of the target electromagnetic wave.
Circularly polarized antenna.

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