JPH0537228A - Circularly polarized wave microstrip antenna - Google Patents

Abstract

PURPOSE:To provide the circularly polarized wave microstrip antenna in which its frequency is adjusted in both upper and lower directions without giving effect on other characteristics. CONSTITUTION:The microstrip antenna is an antenna 1 in which a ground conductor is formed to one side of a dielectric substrate 4 and a radiation conductor 2 is formed to the other side and a feeding point P provided to the radiation conductor 2 with eccentricity is energized. Projections 23a-23d or notches for axis ratio adjustment are formed respectively to angular positions of 45X(2N+1) deg. (N is an integer) with respect to a direction typing a center O and the feeding point P at the outer circumferential end of the radiation conductor 2 and projections 21a-21d or notches for frequency adjustment are formed respectively and one or two over projections 22a-22d for frequency adjustment are formed respectively to angular positions of 90N deg. (N is an integer).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circularly polarized microstrip antenna in which a ground conductor is formed on one surface of a dielectric substrate and a radiation conductor is formed on the other surface.

[0002]

2. Description of the Related Art Conventionally, as shown in, for example, Japanese Unexamined Patent Publication No. 3-80603, a projection or notch for generating a circularly polarized wave is formed at a specific position on the outer peripheral edge of a radiation conductor, and the radiation conductor is eccentric. There is known a circularly polarized microstrip antenna that is fed to a feeding point provided in such a manner.

FIG. 7 is a plan view showing an embodiment of the conventional circular polarization microstrip antenna described above. In the conventional circularly polarized microstrip antenna 7 shown in the figure, a ground conductor (not visible in the figure) is formed on the entire one surface of a rectangular dielectric substrate 9, and a radiation conductor 8 is formed at the center of the other surface. Is formed, and power is fed from the ground conductor surface side to a feeding point P of a radiation conductor 8 provided eccentrically in the radial direction from the center O by a coaxial cable (not shown).

The radiation conductor 8 has a circular shape with a radius R,
On the straight line M2 inclined by 45 ° with respect to the straight line M1 connecting the center O and the feeding point P, the rectangular protrusion 8 is formed at the outer peripheral edge portion.
1a and 81b are formed, and the straight line M1 is -45.
On the inclined straight line M3, the notch 82 is formed at the outer peripheral edge.
a and 82b are formed.

The projections 81a, 81b and the notches 82a,
Reference numeral 82b serves as a mode degeneration / separation element for generating circularly polarized waves, and these projections 81a, 81
When the lengths of b and the notches 82a and 82b are changed, the axial ratio, which is the ratio of the long diameter to the short diameter of the circularly polarized wave, changes, and
The resonance frequency that minimizes the axial ratio is changed.

That is, when the length L1 of the protrusions 81a and 81b is shortened, the resonance frequency rises and the notch 82 is formed.
When the length L2 of a and 82b is increased, the resonance frequency is lowered.

Therefore, conventionally, the circularly polarized microstrip antenna 7 is formed by cutting the protrusions 81a, 81b and the notches 82a, 82b and adjusting the length L1 of the protrusions 81a, 81b or the length L2 of the notches 82a, 82b. There has been proposed a method of adjusting the frequency.

[0008]

The conventional circularly polarized wave microstrip antenna 7 described above has a projection 81 for generating a circularly polarized wave.
It is difficult to adjust both the axial ratio of the circularly polarized wave and the resonance frequency at the same time by cutting the a and 81b and the cutouts 82a and 82b.

Further, projections 81a and 81b for generating circularly polarized waves
If the length L1 and the length L2 of the cutouts 82a and 82b are changed, the characteristics such as the input impedance and the directivity are also affected, and it is difficult to adjust only the frequency.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a circularly polarized microstrip antenna capable of adjusting frequency without affecting other characteristics such as axial ratio. And

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a ground conductor is formed on one surface of a dielectric substrate and a radiation conductor is formed on the other surface thereof. A circularly polarized microstrip antenna that is fed to a feeding point provided eccentrically to a radiation conductor, wherein the radiation conductor is an end portion of an outer peripheral edge of the radiation conductor with reference to a direction connecting a center and the feeding point. A projection or a notch for adjusting the axial ratio is formed at a position of 45 × (2N + 1) ° (N is an integer), and one or more projections for adjusting the frequency are provided at a position of 90 N ° (N is an integer). Are formed. A cutout may be formed in place of the frequency adjustment projection (claim 2).

According to the third aspect of the present invention, the grounding conductor is formed on one surface of the dielectric substrate, and the radiation conductor is formed on the other surface of the dielectric substrate. A circularly polarized microstrip antenna that is respectively fed to a point and a second feeding point, wherein the radiation conductor is an outer peripheral edge portion of the radiation conductor with respect to a direction connecting a center and the first feeding point. 0 ° and 180 ° with respect to the direction connecting the position and center of 0 ° and 180 ° to the second feeding point.
One or two or more frequency adjusting protrusions are formed at each position. A cutout may be formed instead of the frequency adjusting protrusion (claim 4).

[0013]

According to the first aspect of the present invention, the radiation conductor is formed at the outer peripheral edge portion at each of the specific positions.
Alternatively, the two or more protrusions are adjustment units for adjusting the resonance frequency, and when the length of the protrusion is changed, the resonance frequency is changed without affecting other characteristics such as directivity and input impedance. It can be done.

That is, when the length of the protrusion is shortened, the resonance frequency increases, and when the length of the protrusion is increased, the resonance frequency decreases.

Therefore, in the circularly polarized microstrip antenna, the projections formed on the outer peripheral edge of the radiating conductor are cut by the same amount, and the length thereof is shortened to affect other characteristics. The resonance frequency can be adjusted by gradually increasing the frequency.

According to the second aspect of the present invention, the notch can change the resonance frequency without affecting other characteristics such as directivity and input impedance. Reducing the length increases the resonance frequency, and increasing the length of the notch decreases the resonance frequency.

Therefore, in the circularly polarized microstrip antenna, each of the notches formed at the outer peripheral edge of the radiating conductor is cut by the same amount, and the length thereof is lengthened to affect other characteristics. The resonance frequency can be adjusted by gradually reducing the frequency.

According to the third or fourth aspect of the invention, the one or more projections or notches formed at the outer peripheral edge of the radiation conductor at the specific positions are the same as those described above. It is an adjusting unit that can adjust the frequency without affecting other characteristics such as directivity and input impedance. Reducing the length of the protrusion increases the resonance frequency, and increasing the length of the protrusion decreases the resonance frequency. Further, if the length of the cutout is shortened, the resonance frequency increases, and if the length of the cutout is increased, the resonance frequency decreases.

Therefore, in the circularly polarized microstrip antenna, each protrusion or each notch formed at the outer peripheral edge of the radiation conductor is cut by the same amount, and the length of each protrusion is shortened or each notch is cut. By increasing the length, the resonance frequency can be adjusted by gradually increasing or decreasing the frequency without affecting other characteristics such as directivity and input impedance.

[0020]

1 is a plan view showing an embodiment of a circularly polarized microstrip antenna according to the present invention. FIG. 2 is a sectional view taken along the line AA of FIG.

The circularly polarized microstrip antenna 1 is
A circular radiating conductor 2 having a diameter R sufficiently shorter than the diameter D of the dielectric substrate 4 is formed in the central portion of the upper surface of the circular dielectric substrate 4 having the ground conductor 3 formed on the entire lower surface. Power is supplied from the side of the grounding conductor 3 to the feeding point P provided by being eccentric in the radial direction from the center O of the radiation conductor 2 by the coaxial cable 5. The outer conductor 5a of the coaxial cable 5 is connected to the ground conductor 3, and the inner conductor 5b penetrates the dielectric substrate 4 and is connected to the radiation conductor 2 on the upper surface.

At the outer peripheral edge of the radiation conductor 2, the direction of 45 × (2N + 1) ° (N is an integer) with respect to the radial direction from the center O of the radiation conductor 2 through the feeding point P,
That is, rectangular protrusions 21a to 21d having a width Wt and a length Lt are formed at positions in the 45 °, 135 °, 225 °, and 315 ° directions, respectively. The protrusions 21a,
The length Lt of 21c is longer than the protrusions 21b and 21d.

The projections 21a to 21d are mode degeneracy separation elements for radiating circularly polarized radio waves, and the projections are provided at least at any one of the four locations on the outer peripheral edge of the radiation conductor 2. If formed, circularly polarized waves can be generated.

The projections 21a to 21d can change the axial ratio, which is the ratio of the major axis to the minor axis of circularly polarized wave, by changing the length Lt thereof.
The resonance frequency that minimizes the axial ratio can be changed. When the length Lt of the protrusions 21a to 21d is shortened, the resonance frequency at which the axial ratio becomes the minimum increases, and when the length Lt is increased, the resonance frequency decreases.

Therefore, as will be described later, the projections 21a ...
By adjusting the length Lt of 21d, the axial ratio, which is the ratio of the major axis to the minor axis of the circularly polarized wave, is adjusted.

In order to radiate circularly polarized radio waves,
A cutout may be provided instead of the projections 21a to 21d, and the axial ratio may be adjusted by adjusting the length of the cutout. In the case where the notch is provided, conversely to the case of the protrusion, if the length is shortened, the resonance frequency at which the axial ratio becomes the minimum is lowered, and if it is lengthened, the resonance frequency is raised.

At the outer peripheral edge of the radiating conductor 2, at the position in the 90 N ° (N is an integer) direction with respect to the radial direction, that is, in the 0 °, 90 °, 180 °, 270 ° direction. Are rectangular protrusions 22 having a width W and a length L, respectively.
a to 22d are formed.

The protrusions 22a to 22d are frequency adjusting units for adjusting the resonance frequency of the circularly polarized microstrip antenna 1, and the length L of the protrusions 22a to 22d is L.
By increasing, it is possible to lower the resonance frequency,
When the length is shortened, the resonance frequency can be increased.

Therefore, as will be described later, the protrusions 221a to 221 formed at the above-mentioned four locations on the outer peripheral edge of the radiation conductor 2.
By cutting d by the same amount and shortening its length L, resonance is achieved without affecting the characteristics of the circularly polarized microstrip antenna 1, such as directivity, input impedance, and axial ratio of circularly polarized waves. It is possible to adjust the frequency by gradually increasing the frequency.

In the present embodiment, the frequency adjusting projections 22a to 22d are provided at the above four locations on the outer peripheral edge of the radiation conductor 2.
Are formed, as shown in FIG.
Instead of 2d, notches 23a to 23d having a width d and a length S may be formed.

When the cutouts 23a to 23d are formed, the cutouts 23a to 23d are opposite to the projections 22a to 22d.
When the length S of 23d is increased, the resonance frequency can be lowered, and when shortened, the resonance frequency can be increased.

Therefore, the above-mentioned 4 of the outer peripheral edge of the radiation conductor 2 is used.
By cutting each of the notches 23a to 23d formed in the same place by the same amount and lengthening the length S thereof, the resonance frequency is gradually lowered without affecting other characteristics of the circularly polarized microstrip antenna 1. Then, it becomes possible to adjust the frequency.

FIG. 4 shows the length L of the protrusions 22a to 22d.
It is a figure which shows an example of the experimental result of the amount of change of the resonance frequency with respect to the length S of the notches 23a-23d.

In the figure, the resonance frequency is about 1.575G.
Using the circularly polarized microstrip antenna 1 of Hz, the projections 2 formed at the above-mentioned four locations on the outer peripheral edge of the radiation conductor 2
2a to 22d or the notches 23a to 23d are simultaneously changed by the same amount, and the change of the resonance frequency is examined.

In the figure, the protrusions or notches have a length of 0 mm, which means that the protrusions 22a to 22d also have the notches 23a to 23d.
23d is also not formed, and shows the change amount of the resonance frequency when the length L of the protrusions 22a to 22d or the length S of the notches 23a to 23d is changed with the resonance frequency at this time as a reference. .

The circular polarization microstrip antenna 1 used in the experiment has a resonance frequency fo = 1.575 GHz.
The dimensions of each part are: dielectric substrate 4; relative permittivity ε = 21.4, diameter D = 37 m
m, thickness t = 6 mm radiating conductor 2; circular radiating conductor with diameter R = 20.6 mm projections 21a, 21c for adjusting axial ratio; width Wt = 1 mm, length Lt = 2 mm projections 21b, 21d for adjusting axial ratio; width Wt = 1 mm, length Lt = 1 mm Protrusions 22a to 22d; width W = 0.7 mm, length L = 0 to
1 mm notches 23a to 23d; width d = 0.7 mm, length S = 0
It is 1 mm 2.

As can be seen from FIG. 4, the resonance frequency changes substantially in proportion to the length L of the protrusions 22a to 22d or the length S of the notches 23a to 23d, and the rate of change thereof is the protrusion 22a to 22d.
When shortening the length L of 22d, approximately + 10MHz /
mm and the length S of the notches 23a to 23d is increased, it is approximately −10 MHz / mm.

Therefore, the protrusions 22a to 22d or the notch 23
a to 23d are cut in small amounts to shorten the length L of the protrusions 22a to 22d, or the notches 23a to 23d.
By increasing the length S of d, the resonance frequency is increased to several MHz.
The frequency can be finely adjusted by increasing or decreasing in units.

Next, a circularly polarized microstrip antenna 1 provided with a radiation conductor 2 having the projections 22a to 22d is provided.
The frequency adjustment will be described. The resonance frequency of the circularly polarized microstrip antenna 1 is mainly determined by parameters such as the thickness t of the dielectric substrate 4, the relative permittivity ε of the dielectric substrate 4 and the diameter R of the radiation conductor 2. Therefore, the design values of the above three parameters are appropriately selected, and the initial value of the resonance frequency of the circularly polarized microstrip antenna 1 (the radiation conductor 2 and the ground conductor 3 are formed on the front and back surfaces of the dielectric substrate 4 The resonance frequency at which the axial ratio at the time of adjustment is minimized is set to be slightly lower than the target value. For example, in the example shown in FIG. 4 described above, the initial frequency is set to approximately 1.57 GHz.

Next, when the axial ratio of circularly polarized waves is out of the standard value,
The axial ratio of the circularly polarized wave is adjusted within the standard value by carrying out the work of cutting the four axial ratio adjusting protrusions 21a to 21d by the same amount once or several times. Next, the work of cutting the projections 22a to 22d for frequency adjustment by the same amount
The resonance frequency fo is gradually increased by performing the operation once or several times to adjust to the target frequency. For example, in the example shown in FIG. 4 described above, the target frequency is adjusted to 1.575 GHz.

The projections 22a to 22 are formed on the radiation conductor 2.
In the case where the notches 23a to 23d are provided in place of d, the initial frequency is set to be slightly higher than the target value in the opposite manner to the above case, and the notches 23a to 23d are each cut by the same amount once. Alternatively, the resonance frequency f
The value o is gradually decreased to adjust to the target frequency.

In the above embodiment, the radiation conductor 2 of the one-point feeding type circularly polarized microstrip antenna is provided with the frequency adjusting projections 22a to 22d or the notches 23a to 23d. Of the frequency-adjusting projection 22a on the radiation conductor 2 of the circular polarization microstrip antenna
22d or notches 23a to 23d can be provided to obtain the same effect.

FIG. 5 shows the protrusions 22a to 22 for frequency adjustment.
3 shows a radiation conductor 2 of a two-point feeding type circularly polarized microstrip antenna in which d is formed.

A first feeding point P1 and a second feeding point P2 are eccentrically provided at appropriate places on the radiation conductor 2 on straight lines m and n orthogonal to the center O of the circular radiation conductor 2. Positions of the outer peripheral edge of the radiation conductor 2 at 0 ° and 180 ° with respect to the direction connecting the center O and the first feeding point P1, and the center O and the second feeding point. Frequency adjusting protrusions 22a to 22d are formed at positions of 0 ° and 180 ° with respect to the direction connecting P2.

FIG. 6 shows notches 23a to 23 for frequency adjustment.
The radiation conductor 2 of the circularly polarized microstrip antenna of the two-point feeding type in which d was formed is shown, and notch 23a-23 is replaced with protrusion 22a-22d of the radiation conductor 2 shown in FIG.
d is formed.

In the above embodiment, one projection 22a is provided at each of the above-mentioned specific positions on the outer peripheral edge of the radiation conductor 2.
22d or notches 23a to 23d are provided, but two or more protrusions 22a to 22d or notches 23a to 2d, respectively.
You may make it provide 3d.

The frequency adjusting protrusions 22a to 22d or the notches 23 are provided at the specific positions of the outer peripheral edge of the radiation conductor 2 having a rectangular shape or any other shape, not limited to the circular shape.
You may form a-23d.

[0048]

As described above, according to the present invention,
In a one-point feed type circularly polarized microstrip antenna in which a ground conductor and a radiation conductor are formed on the front and back surfaces of a dielectric substrate, an outer peripheral edge portion of the radiation conductor, a radiation conductor center and a feeding point are provided. Since 1 or 2 or more protrusions for frequency adjustment are formed at 90 N ° (N is an integer) direction with respect to the direction connecting the two, the protrusions are cut and the length thereof is shortened to obtain other characteristics. The frequency can be adjusted upwards without affecting the.

Further, since the notch is formed in place of the frequency adjusting projection, the notch is cut and the length thereof is increased to adjust the frequency downward without affecting other characteristics. You can

Further, in a two-point feed type circularly polarized microstrip antenna in which a ground conductor and a radiation conductor are formed on the front and back surfaces of a dielectric substrate, the outer peripheral edge of the radiation conductor is located at the center and Frequency of 1 or 2 or more at positions of 0 ° and 180 ° with respect to the direction connecting the first feeding point and at positions of 0 ° and 180 ° with respect to the direction connecting the second feeding point and the center, respectively. Since the adjustment protrusion or notch is formed, the frequency can be adjusted upward or downward without affecting other characteristics as in the above.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a circular polarization microstrip antenna according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a diagram showing a shape of a radiation conductor of a second embodiment of the circularly polarized microstrip antenna according to the present invention.

FIG. 4 is a diagram showing the amount of change in frequency with respect to the length of a protrusion or notch for frequency adjustment.

FIG. 5 is a diagram showing the shape of a radiation conductor of a third embodiment of the circularly polarized microstrip antenna according to the present invention.

FIG. 6 is a diagram showing a shape of a radiation conductor of a fourth embodiment of the circularly polarized microstrip antenna according to the present invention.

FIG. 7 is a plan view showing an embodiment of a conventional circularly polarized microstrip antenna.

[Explanation of symbols]

1 circular polarized microstrip antenna 2 Radiation conductor 3 Ground conductor 4 Dielectric substrate 5 Coaxial cable for feeding 21a-21d, 22a-22d Protrusion 23a-23d Notch P feeding point

Claims (4)

[Claims] 1. A circularly polarized microstrip in which a grounding conductor is formed on one surface of a dielectric substrate and a radiation conductor is formed on the other surface, and power is fed to a feeding point provided eccentrically to the radiation conductor. In the antenna, the radiating conductor is an end portion of an outer peripheral edge of the radiating conductor and is used for adjusting an axial ratio at a position of 45 × (2N + 1) ° (N is an integer) with reference to a direction connecting a center and the feeding point. Protrusions or notches are formed, and 1 or 2 at 90 N ° (N is an integer), respectively.
A circularly polarized microstrip antenna characterized in that the above-mentioned protrusion for frequency adjustment is formed. 2. The circularly polarized microstrip antenna according to claim 1, wherein the radiation conductor is formed with a notch instead of the protrusion for frequency adjustment. 3. A first feeding point and a second feeding point eccentrically provided with a ground conductor formed on one surface of the dielectric substrate and a radiation conductor formed on the other surface of the dielectric substrate. A circularly polarized microstrip antenna that is fed to the antenna and the radiation conductor at the outer peripheral edge of the radiation conductor, and is 0 ° with respect to the direction connecting the center to the first feeding point.
1 and 2 or more frequency adjusting protrusions are formed at positions of 0 ° and 180 ° with respect to the direction connecting the position and center of 180 ° and the second feeding point, respectively. Circularly polarized microstrip antenna. 4. The circularly polarized microstrip antenna according to claim 3, wherein the radiation conductor is formed with a notch instead of the protrusion for frequency adjustment.