JP2505663B2 - Printed antenna - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave transmitting / receiving printed antenna.

[0002]

2. Description of the Related Art A printed antenna having an antenna element and a transmission line formed on a printed circuit board has many advantages such as thinness, light weight, small size, suitable for mass production, and easy integration with an electronic circuit. It is used as an antenna for transmitting and receiving microwaves for broadcasting and mobile communications. There are various types of printed antennas, but a printed antenna with a wide band by using a linear strip antenna element and providing a window on the opposite side of the strip antenna element from which the grounding conductor is removed by sandwiching the substrate is Unlike other printed antennas that use a patch-type element or the like, attention is paid to the fact that there is only one resonance mode and the operation is stable.

Further, when this linear strip antenna element is used as an antenna for circularly polarized wave transmission / reception used for satellite broadcasting transmission / reception, etc., it is also combined with a slot antenna element which is also a linear element for excitation. It has been proposed to dispose along the transmission line such that the feeding phase difference is 90 degrees. With this arrangement, the radiated electric field of the strip element and the radiated electric field of the slot element are spatially orthogonal to each other, so that there is a phase difference of 90 degrees in time and a combination of the spatially orthogonal oscillating electromagnetic fields. Therefore, it is possible to efficiently radiate circularly polarized waves. (While the above description of the antenna relates to the transmitting antenna,
Due to the duality of the electromagnetic field, it is used for both transmission and reception).

In addition to the characteristic of the linear element that the operation is stable, the printed antenna constituted by the combination of the linear elements in this manner has a right-handed circularly polarized wave and a left-handed circularly polarized wave by the combination with the active element. It is also possible to electronically switch the linearly polarized wave used in satellite broadcasting using a communication satellite.

Therefore, using a patch type element or the like,
Compared with other printed antennas designed to transmit and receive circularly polarized waves for each element, it is possible to realize a more multifunctional antenna.

Although it has been described that the frequency band of the strip antenna element is widened by the window obtained by removing a part of the ground conductor, electromagnetic waves are simultaneously radiated to both sides of the antenna. In order to radiate the electromagnetic field radiated on both sides of such an antenna to only one side, the conventional example shown in FIG.
The reflection plate 20 as shown in FIG. The reflector may be provided on either side of the substrate, but as shown in FIG. 8, in order to simultaneously achieve the purpose of reducing radiation loss from the transmission line, the reflector is provided on the side of the transmission line where the central conductor is located. Is preferably provided.

In order to improve the deterioration of the circular polarization characteristic due to the addition of the reflector, a proposal of providing a strip antenna in the window has been made by the same inventor as the present invention (Patent application No. 1-344299).

Conventional examples of printed antennas that radiate circularly polarized waves by combining the linear elements described above are shown in FIGS.

FIG. 6 is a plan view showing a conventional example of a printed antenna that radiates circularly polarized waves by combining linear elements, and FIG. 7 is a conventional strip antenna with a window that constitutes the printed antenna of FIG. 9 is a plan view showing a pair of an element and a slot element, and FIG. 8 is a view showing a reflector together with FIG.
9 is a sectional view taken along the line 8-8 in FIG.

Referring to these drawings, the linear strip antenna element 10 is provided inside the window 14, and by electromagnetic coupling with the transmission line 12, the electromagnetic wave of frequency f0 determined by the length of the linear strip antenna element is efficiently generated. It radiates well. The window 14 operates as a slot having a wide width and a long length, so that unnecessary radiation is generated with respect to radiation from the strip antenna element 10. This unnecessary radiation can be suppressed by providing a pair (not shown) that cancels each other.

[0011]

However, in the conventional printed antenna, it is only in a certain direction that the unwanted radiation can be completely canceled by using the above-mentioned method.
It was limited to point frequencies. Further, since the gain is reduced due to the disturbance of the radiation pattern due to the unnecessary radiation, it is necessary to further perform the design for correcting the disturbance of the radiation pattern in the entire array antenna, which has a disadvantage of poor designability.

In view of the above situation, the present invention has a small amount of unnecessary radiation from a window, a good designability, a wide frequency band, a high gain, and a microwave without providing a pair for canceling unnecessary radiation. It is to provide a print antenna for transmission and reception.

[0013]

To achieve the above object, the present invention provides a window formed in a ground conductor provided on one surface of an insulating substrate and a strip antenna element formed in the window. And a strip conductor, and the window has a convex portion projecting in a direction toward the central portion at a position of the central portion in the length direction of the strip conductor. It is a thing.

[0014]

According to the present invention, by providing a convex portion for partially narrowing the width of the window at the central portion of the strip conductor, unnecessary radiation from the window can be reduced without narrowing the frequency band of the strip antenna element. It is capable of If the window width of the central portion is too wide, unwanted radiation is generated in the same manner as when the convex portion is not provided. Is desirable.

The electric field distribution on the strip antenna element is
It is strongest at the end, and the band of the strip antenna element can be widened by widening the window at this part. The electric field at the central portion of the strip antenna element is zero, and the characteristics of the strip antenna element do not change in this portion even when the window, which is a part of the ground conductor, approaches. Therefore, the tip of the convex portion of the window may be connected to the strip antenna element, but since the resonance frequency of the strip antenna element changes depending on the width of the tip portion of the convex portion, the width of the tip portion of the convex portion is the strip antenna. It is desirable that the width is less than or equal to the width of the device.

The reflector usually has a wavelength of λ at the used frequency.
Is placed at a position of λ / 4, but it is not particularly limited to the above value as long as the purpose of radiating an electromagnetic wave to one of the antennas can be achieved. Further, another insulator substrate may be sandwiched between the antenna and the antenna to fix the position of the reflector.

The insulating substrate of the antenna is not particularly limited as long as it has a constant thickness and desired dielectric characteristics.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.
1 is an enlarged plan view of an essential part of a first embodiment of a printed antenna of the present invention, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG. FIG. 4 is an enlarged plan view of an essential part of a second embodiment applied to a circularly polarized circular transmission / reception print antenna, FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3, and FIG. It is a top view which shows the whole 3rd Example which applied the printed antenna of 1 to the circular polarized-wave transmission / reception printed antenna.

Referring to FIGS. 1 and 2, the thickness is 0.8 m.
The window 14 is formed by removing the strip antenna element 10 having a width of 1.0 mm and a length of 7.5 mm and the grounding conductor 18 around the strip antenna element 10 on one surface of the insulating substrate 16 of m. Inside, the convex portions 11 of the grounding conductor 18 protruding from both sides toward the central portion of the strip antenna element were formed. The distance between the tips of the protrusions 11 is 1.8 mm,
The width of the tip of the protrusion 11 was 0.4 mm. The transmission line 12 for excitation was formed on the other surface of the insulating substrate 16. The position of the end of the window is set to the transmission line 12 for excitation.
Was 0.8 mm.

Next, referring to FIGS. 3 and 4, these drawings show an example in which the printed antenna antenna shown in FIGS. 1 and 2 is applied to a circularly polarized wave transmitting / receiving printed antenna with a reflector. There is. This printed antenna has the same structure as the above-mentioned printed antenna except that a slot antenna element 22 and a reflector 20 are added.

The slot antenna element 22 has a design frequency of 12 GHz and is formed by removing the portion of the grounding conductor 18, and is 4.2 mm from the window strip antenna element (corresponding to a quarter wavelength on the transmission line). ) Position. The reflection plate 20 was arranged at the position of the rear ¼ wavelength on the transmission line side of the substrate.

FIG. 5 shows an example of a circularly polarized wave transmitting / receiving print antenna configured by using the print antennas shown in FIGS. 3 and 4 as a basic element.

The strip antenna element 10 and the slot antenna element 22 are provided on one side of the transmission line 12, respectively.
Two rows were arranged along the line at intervals of 6.8 mm (one wavelength on the transmission line). The input / output unit 13 is provided at the center of the transmission line of each column so that the antenna elements of each column are excited in the same phase.

In the antenna shown in FIG. 5, the frequency at which the maximum gain was obtained was 11.9 GHz, and the axial ratio (the degree of good circular polarization) coincided with the best frequency. Also,
When the radiation pattern in the plane perpendicular to the transmission line was measured, the maximum value of the first side lobe level was -10 dB, and the difference between left and right was 2 dB.

As a comparison, in the structure of the conventional printed antenna of FIG. 6 (that is, without providing the convex portion of the window), the length and position of the strip antenna element and the slot antenna element are adjusted so as to obtain the maximum gain. did. Maximum gain is 1
1.6 GHz is obtained, and the frequency with the best axial ratio is 1
It was 1.9 GHz. At this time, the position of the edge of the window is
It was 0.2 mm from the transmission line for excitation. Also, when the radiation pattern was measured in the same manner, the maximum value of the first side lobe level was −5 dB, and the difference between the left and right sides was 10 dB.

As described above, in the configuration of the present invention, the frequency at which the maximum gain is obtained and the frequency at which the axial ratio is good match, unlike the conventional example, and at the same time, the disturbance of the radiation pattern due to unnecessary radiation from the window is suppressed. You can see that it is being done. In other words, the antenna having the convex portion on the window has improved the disturbance of the radiation pattern due to unnecessary radiation. At the same time, the position of the end of the window could be separated from the transmission line (in this example,
What was 0.2 mm became 0.8 mm), so
It can be seen that the characteristics of the transmission line hardly changed and the frequency with a good axial ratio coincided with the frequency with which the maximum gain was obtained, thus improving the designability.

[0027]

As described in detail above, according to the present invention, a printed antenna having a wide frequency band and good design can be obtained.

[Brief description of drawings]

FIG. 1 is an enlarged plan view of a main part of a first embodiment of a printed antenna according to the present invention.

2 is a cross-sectional view taken along line 2-2 of FIG.

FIG. 3 is an enlarged plan view of an essential part of a second embodiment in which the printed antenna is applied to a circularly polarized wave transmitting / receiving printed antenna with a reflecting plate.

4 is a cross-sectional view taken along line 4-4 of FIG.

FIG. 5 is a plan view showing an entire third embodiment in which the printed antenna of FIG. 1 is applied to a circularly polarized wave transmitting / receiving printed antenna.

FIG. 6 is a plan view showing a conventional example of a printed antenna that radiates circularly polarized waves by combining linear elements.

FIG. 7 is a plan view showing a pair of a conventional strip antenna element with a window and a slot element, which constitutes the printed antenna of FIG.

8 is a cross-sectional view taken along line 8-8 of FIG. 7 showing also the reflector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Strip antenna element 11 Convex part of window 12 Transmission line 13 Input / output section 14 Window 16 Insulator substrate 18 Grounding conductor 20 Reflector 22 Slot antenna element

Claims (6)

(57) [Claims] 1. A window formed in a ground conductor provided on one surface of an insulating substrate, and a strip conductor formed as a strip antenna element in the window, the window being the strip conductor. A printed antenna having a convex portion projecting in a direction toward the central portion at a position of the central portion in the length direction. 2. The printed antenna according to claim 1, wherein the convex portion is substantially symmetrical with respect to an axis of the strip conductor, and a distance between tips of the convex portion is equal to a width of the strip conductor. A printed antenna characterized by being 1 times or more and 3 times or less. 3. The printed antenna according to claim 1, wherein a width of a tip portion of the convex portion is equal to or smaller than a width of the strip conductor. 4. The printed antenna according to claim 1, further comprising a slot antenna element formed in the ground conductor in association with the strip conductor. 5. The printed antenna according to claim 1, wherein the printed antenna is a basic element, and a plurality of the basic elements are provided on an insulating substrate.
A printed antenna characterized in that. 6. The printed antenna according to claim 1, wherein the insulating substrate is provided with reflectors at intervals.