JPH0563110U - Broadside array antenna - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] One of the null points generated on the left and right of the main beam of the antenna, whose position is constant even if the used frequency changes, even if the used frequency is wide band. Providing a broadside array antenna that can eliminate interfering waves by utilizing points. [Structure] In a broadside array antenna, all antenna element groups 1 to 4 constituting the broadside array antenna are divided into two at the center, and one antenna element group and the other antenna element group have mutually inverted phases Λ / 2 of the set frequency F ₀ for each antenna element 1 and 2 of the one antenna element group.
The transmission lines having the lengths corresponding to are added.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a broadside array antenna, and in particular, among the first null points that do not generate radiation on the left and right of the main beam of the electric field directivity of the antenna, one of the null points is used as the frequency. The present invention relates to a broadside array antenna that can always be kept constant regardless of the situation.

[0002]

[Prior Art]

 Array antennas in which a plurality of antenna elements are arranged and all or some of the antenna elements are excited are known. This type of array antenna can have various functions that cannot be obtained with a single antenna radiation element, depending on the type of antenna element, the arrangement method, the excitation method, and the like. In general, array antennas use the same shaped antenna element.

An array antenna in which the main radiation direction of the main beam of the antenna is a direction orthogonal to the array direction of the antenna elements is called a broadside array antenna. In the conventional broadside array antenna, paying attention to the main beam and side lobes, control the feed level and feed phase to each antenna element to perform beam tilt of the main beam or suppress the side lobe level. However, there was no broadside array antenna configured to remove the interfering wave, focusing on the null point of the antenna radiation.

[0004]

[Problems to be solved by the device]

 In recent years, as the demand for effective use of radio waves has increased, attempts are being made to obtain D / U (desired signal to interfering signal ratio) with an interfering wave by utilizing the null point of antenna radiation. On the other hand, in a wideband antenna with a band coverage of about 20% or more, there is a problem that the angle of the null point generated on the left and right of the main beam changes depending on the feeding frequency. For this reason, the method of removing the interfering wave using the null point is effective at a single frequency, but could not be effectively used when used in a wide band.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to change the used frequency among the null points generated on the left and right of the main beam of the antenna even when the used frequency is wide band. Another purpose is to provide a broadside array antenna that can eliminate interfering waves by using one of the null points whose angle is constant.

[0006]

[Means for Solving the Problems]

In order to achieve the above-mentioned object, a broadside array antenna according to the present invention has a large number of all antenna element groups constituting a broadside array antenna divided into two at the center, and one antenna element group and the other antenna element group. The groups are arranged so that their phases are opposite to each other, and a transmission line having a length corresponding to λ / 2 of the set designated frequency F ₀ is added.

[0007]

[Action]

When the above configuration is adopted and power is fed to all antenna element groups of the broadside array antenna in phase, a transmission line of a length corresponding to λ / 2 of the designated frequency F ₀ is set to each antenna element. The first null point generated on the side of the added one antenna element group is always generated at a constant angle regardless of the feeding frequency.

[0008]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a broadside array antenna according to a first embodiment of the present invention.

This array antenna is a broadside array antenna using dipole antennas 1-4 as antenna elements, and the number of antenna elements is four. In the antenna elements 1, 2, 3 and 4 which are divided into two at the center of the whole antenna element group, the center conductor and the outer conductor of the feeding coaxial cable are connected to the left and right to perform phase inversion. Further, the antenna elements are arranged with a distance D therebetween. Reference numeral 5 is a reflector.

Here, the length of the coaxial cables 6, 7 and 8, 9 respectively connected to the antenna elements 1, 2 and 3, 4 is 6, where L is the length of 8, 9. The length of 7 is L + 1. Further, the cables 6, 7 and 8, 9 are connected to the coaxial cables 12, 13 of the same length through the two-division matching devices 10, 11 of the same phase and the same amplitude. Are connected to each other via the two-division matching box 14 having the same phase and the same amplitude as the two-division matching boxes 10 and 11.

2A, the electric field directivity E of the array antenna is as follows: the phase of the antenna element 1 is 0, the voltage amplitude is 1, the phase of the antenna element 2 is φ ₁ , the voltage amplitude is 1, and the antenna element 2 is When the phase is φ ₂ , the voltage amplitude is 1, the phase of the antenna element 2 is φ ₃ , and the voltage amplitude is 1, the following equation (1) is obtained.

[0013]

[Equation 1] Now, with respect to the antenna elements 1 and 2, the antenna elements 3 and 4 are set to have opposite phases in the antenna arrangement. Also, since the cables feeding the antenna elements 1 and 2 are longer than the cables feeding the antenna elements 3 and 4, the antenna elements 3 and 4 have a cable length l (electrical length) with respect to the antenna elements 1 and 2. The phase is advanced by l ′ = l × shortening rate).

Therefore, if φ ₁ = 0, then φ ₂ = φ ₃ = {(2πl ′) / λ} −π, and the following equation (2) is obtained.

[0015]

[Equation 2] Here, if the condition that the electric field is null (E = 0) is {(4πD) / sin θ} + {(2πl ′) / λ} −π = −π, the following equation (3) holds, and E = It becomes 0.

[0016]

[Equation 3] By the way, in order to be {(4πD) / sin θ} + {(2πl ′) / λ} −π = −π, {(4πD) / sin θ} = − {(2πl ′) / λ} Therefore, −sin θ = 1 ′ / 2D.

That is, when the above power supply is performed, an electric field null is generated at an angle of −θ = arksin (l ′ / 2D).

Further, this null angle is determined only by l ′ once the array interval D is determined, and this is independent of frequency.

3A to 3C, the number of antenna elements is 4, the λ / 2 dipole antenna is used as the antenna elements, the antenna element interval D = 156.25 m / m, and the designated frequency F is set. ₀ 6 is a graph showing calculation results of the electric field directivity of the antenna at respective frequencies of 960 MHz, 890 MHz, and 810 MHz when = 960 MHz.

Therefore, the coaxial cables 6 and 7 (length L + 1) of FIG. 1 are 1 (λ / 2 of the designated frequency) × (1 / cable shortening rate) more than the coaxial cables 8 and 9 (length L). It's just longer. That is, the electrical length l ′ = λ / 2 of the specified frequency = 156.25 m / m.

As a result, at 960 MHz, the same electric field directivity can be obtained with all the antenna elements 1, 2, 3, and 4, in-phase and same-width power feeding.

Further, when the first null angle at that time is θ, θ = −arksin {156.25 / (2 × 156.25)} = − 30 °. From this, it is understood that the first null angle -30 degrees does not change even when the power supply frequency is changed, and the first null angle always occurs at -30 degrees. However, the first null angle generated in the +30 direction angle changes depending on the frequency.

FIGS. 4A to 4C show a general side-by-side and same-amplitude feeding with four antenna elements and four antenna elements for comparison with the electric field directivity of the broadside array antenna of the present invention. The electric field directivities of the λ / 2 dipole antenna and the broadside array antenna with the antenna element spacing D = 156.25 m 2 / m at 960 MHz, 890 MHz, and 810 MHz are respectively shown.

As for the first null angle, it is understood that the first null angle changes when the feeding frequency is changed as described above in both the positive and negative directions.

FIG. 5 is a second embodiment in which the present invention is applied to a beam-tilt type broadside array antenna in which a constant phase difference is further added to each antenna element and the antenna is tilted in the maximum electric field direction. A broad side array antenna in which the maximum electric field direction of the side array antenna is tilted instead of 0 ° is called a beam tilt type. This can be realized by adding a constant phase in the order in which the antenna elements are arranged as shown in FIG. This is a well-known fact, and in order to materialize this, a cable corresponding to this phase may be added (Fig. 2 (C)).

The present invention is applied to the broadside array antenna having the beam tilt as shown in FIG. 5, which is the second embodiment.

The number of antenna elements is four, and between the antenna elements 21, 22 and 23, 24 divided into two at the center of the entire antenna element group, the power feeding axis is the same as in the first embodiment. The connection between the center conductor of the cable and the outer conductor is reversed, and the phase is reversed. The length of the coaxial cable 26 connected to each antenna element is L + 1 as in the first embodiment, and the length of the cable 27 is L + 1 in the first embodiment, but the beam tilt component example is also performed at the same time. , An additional cable a for beam tilt is added. Therefore, the length of the cable 27 is L + l + a. Similarly, the cable 28 becomes L + 2a by adding the cable L of the present invention and the cable 2a for beam tilt. Further, the length of the cable 29 is similarly L + 3a.

Reference numeral 25 is a reflector, 30, 31, 34 are in-phase and same-amplitude two-division matching devices, and 32, 33 are coaxial cables having the same length. The distance between the antenna elements is D.

Now, assuming that the antenna element spacing D = 156.25 m / m and the designated frequency F ₀ = 960 MHz, l = the designated frequency F ₀ λ / 2 = 156.25 m / m.

Further, a is a phase difference for performing beam tilt, and a tilt angle of 10 degrees corresponds to a = D × sin 10 degrees = 27.13 m / m.

Based on this, the results of calculating the electric field directivity of the antenna at each frequency of 960 MHz, 890 MHz, and 810 MHz are shown in FIGS. 6 (A)-(C), respectively.

As shown in these figures, it is understood that the angle of the first null point in the negative direction hardly changes even when the feeding frequency is changed.

[0033]

[Effect of the device]

 As described above, according to the present invention, particularly in a mobile phone base station or mobile phone base station used in a wide band, interference waves from other areas using the same frequency outside its own area can be efficiently removed. be able to.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a broadside array antenna according to the present invention.

FIGS. 2A, 2B, and 2C are diagrams showing an array example of antenna elements.

3A, 3B and 3C are graphs showing calculated values of electric field directivity of the antenna of the first embodiment of the present invention.

4A, 4B, and 4C are graphs showing calculated values of electric field directivity of a broadside array antenna when the present invention is not implemented.

FIG. 5 is a perspective view showing a second embodiment of the beam tilted broadside array antenna according to the present invention.

6 (A), (B) and (C) are graphs showing calculated values of electric field directivity of the broadside array antenna of the second embodiment of the present invention.

[Explanation of symbols]

1 antenna element 2 antenna element 3 antenna element 4 antenna element (21, 22, 23, 24) 6 feeding coaxial cable 7 feeding coaxial cable 8 feeding coaxial cable 9 feeding coaxial cable 12 feeding coaxial cable 13 feeding coaxial cable (26, 27, 28, 29, 3
2, 33) 10 2 distribution matching device 11 2 distribution matching device 14 2 distribution matching device (30, 31, 34)

Claims (2)

[Scope of utility model registration request] 1. In a broadside array antenna, all the antenna element groups forming the broadside array antenna are divided into two at the center, and one antenna element group and the other antenna element group have mutually inverted phases. A broadside array antenna, wherein the broadside array antenna is arranged and a transmission line having a length corresponding to λ / 2 of a set frequency F ₀ is added to each antenna element of the one antenna element group. 2. In a broadside array antenna, all the antenna element groups forming the broadside array antenna are divided into two at the center, and one antenna element group and the other antenna element group have mutually inverted phases. A broadside array antenna, which is characterized in that a transmission line having a length such that a different phase difference is given to each antenna element of the entire antenna element group is provided.