JPH01101006A - Broad side array antenna - Google Patents

Abstract

PURPOSE:To facilitate a feeding to an antenna and, simultaneously, to improve a directivity gain by arranging feeding elements and passive element in a specific wavelength interval and causing a radiation current to flow to the passive elements by means of a mutual induction. CONSTITUTION:A broad side array antenna is composed by arranging three column dipoles on a straight line and, simultaneously, so that respective elements can be made vertical to the straight line. An antenna element 1 located in the center of the broad side array antenna is the feeding element, and antenna elements 2 and 3 at both sides are the passive elements. Thus, the constitution is so made that the radiation current can be made to flow to the antenna elements 2 and 3 by the mutual induction at the time of feeding the antenna element 1, and that a wave can be radiated. At such a time, the passive element is set at a proper values slightly shorter than the feeding elements 2 and 3, and an element interval is made to be 0.5- 1lambda. Thus, feeding points to the broad side array antenna can be reduced, the constitution of the antenna can be made easy, and a cost-down can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a broadside array antenna.

C. Prior Art and Its Disadvantages Array antennas generally used for TV reception etc. can have various antenna functions depending on the type of antenna elements, arrangement method, excitation method, etc. Furthermore, the width of the main beam of the radiation directivity can be set by directivity synthesis to obtain the desired directivity.

Among such array antennas, there is a broadside array antenna in which a plurality of antenna elements are arranged in a straight line and radiation is maximized in a direction perpendicular to the direction in which the antenna elements are arranged.

Conventional broadside array antennas are configured to feed power to each antenna element.

Therefore, it is necessary to supply power with a predetermined amplitude and phase to each antenna element. however,
In order to reduce side lobes in the directional characteristics of the broadside array antenna, the interval between each antenna element is set to an appropriate length slightly smaller than one wavelength. Therefore, power must be supplied to each antenna element with an amplitude and phase corresponding to this.

As described above, in the conventional broadside array antenna, feeding power to each antenna element becomes complicated due to settings such as antenna element spacing and element length.

[Object of the Invention] The present invention has been made in view of the above points, and an object thereof is to provide a broadside array antenna that allows easy power feeding to the antenna and has good directivity gain.

[Invention P Points and Points] In this invention, a feed element and a parasitic element are arranged at intervals of 0.5 to 1 wavelength, and a radiation current flows through the parasitic element by mutual induction.

[First Embodiment of the Invention] A first embodiment of the invention will be described below with reference to the drawings. Figures (a) and (b) are a front view and a side view showing the configuration of a broadside array antenna according to a first embodiment of the present invention. The broadside array antenna shown in the figure is constructed by arranging three cylindrical dipoles in a straight line so that each element is perpendicular to the straight line.

Antenna element 1 located at the center of the broadside array antenna is a feeding element, and antenna elements 2 and 3 on both sides are parasitic elements.

In the above embodiment, among the three antenna elements, only the antenna cable l is the feeding element. For this reason, the other two
The book antenna elements 2 and 3 are configured to cause a radiation current to flow through mutual induction when power is supplied to the antenna cord 1, and to radiate radio waves.

Here, the current flowing through antenna element 1 is I, the current flowing through antenna elements 2 and 3 is 12, and the spacing between each antenna element is d.
l, antenna element length no J! When calculating the case where voltage V is applied to the center of antenna element 1 as l-λ/4, current 2I2/I flowing through antenna elements 2 and 3 and input impedance V/I are as follows.

In the case of d-0,50λ, 2I2/I 0.578 + j O,324, V/
I -75,58+ j21.21d -0,55λ
In the case of 2 12 / I −0,568+ j O,192
, V/I -86,84+ j 25.85d-
For 0.60λ, 2 I 2 / I = 0.586 + j
O,074, V/I -61,13+ j 31.
For 85d -0,85λ, 2 12/ I -0,56[1-j O,052,
V / I -58,46+ j 39.37d 0
．． In the case of 70λ, 212/I -0,548-j O,20B, V/I
In the case of 59.48 + j 47.43d -0,75λ, 212 / I -0,468-j O,3g4,V
/ I -85,16+ 354.28 Here, if the relative gain Gh is, for example, d-0,85λ, the electric field strength is Eo
Then, it becomes as follows.

(1,588Eo) 273.13G h-x --3,088-4,87(dB)Eo
58.4, the relative gain Gh at each element interval is as follows.

d -0,50λ, G h -2,409-3,82d
Bd-0,55λ, Gh meal 2.683-4.29aBd
0.60λ, G h -2,934 4.67dBd
-0, B5λ, G h -3,088 4.87dB
d -0,70λ, G h -2,947-4,89a
Bd -0,75λ, Gh■2.419-3.84dB
As mentioned above, the maximum gain Gh is d −0
, 65λ, it becomes G h −3,088.

In this way, the current ■2 of the parasitic element at the element spacing d −0,65λ is I 2− (0,588−j
O,052)I, and in this case, the second term is a negligible value, so a current in phase with the current I of the feeding element flows.

In addition, the input impedance V/I is V/l-58,4
8+ j 39J7 (Ω), which is a value that can be sufficiently matched with the power supply line.

As described above, in a broadside array antenna configured with a feed element and a plurality of parasitic elements, a radiation current can be caused to flow through the parasitic elements due to mutual induction caused by a current flowing through the feed element.

Next, under the condition that the current flowing through the feeding element and the parasitic element are in phase, the antenna element length is half a wavelength (λ/2).
A slightly shorter length has a greater effect.

This will be explained with reference to FIGS. 1 to 3.

FIGS. 2 and 3 are diagrams showing the configuration of a broadside array antenna consisting of five and seven antenna elements, respectively. In each broadside array antenna, only the antenna element located at the center is a feeding element, and the other antenna elements are parasitic elements. Here, the element length and element spacing of the broadside array antenna configured as described above are set as follows.

In the case of 3 pieces, Iz/no 0.94, d > / J2-
In the case of 2.95 pieces, no 1/, l'-0,94, d, /no 28912/, ff-0.94, d2/no 3.47
For books, 11/i=0.94, d1/no 2.912
/I! -0,94,d2/no 3.4I! s/i-0,
98, d3/No 3.6 The gain in the case of multi-value setting as described above is indicated by O in FIG. The horizontal axis in FIG. 4 is A/λ2 (A is the antenna element arrangement area), and the vertical axis is the directivity gain Gh, which is given by the following equation.

However, η is the aperture efficiency, and the case where it is 100% is shown by a broken line in FIG. In addition, in the figure, a is 3 elements, b is 5 elements,
C indicates the gain of the antenna consisting of seven elements. Note that B and Δ marks indicate the gain values of the broadside array antenna in a second embodiment to be described later.

As shown in FIG. 4, the aperture efficiency of the antenna with any number of elements is lower than 100%. However, in the case of three elements, A/λ2, which is the element array area divided by the square of the wavelength, is
Both the antenna set to NONO 1-λ/4, d-〇, B5λ and the antenna with the element length and element spacing set as above are approximately equal to 0.7, but the gain Gh is NONO 1.
When set to -λ/4, the normal value is 4.87 dB, but it increases to 7.7 dB.

In this way, by setting the parasitic element to an appropriate value slightly shorter than the feeding element and setting the element spacing to 0.5 to 1[lambda], a high-gain broadside array antenna can be constructed. This also applies to antennas composed of five elements and seven elements.

In the above embodiment, a broadside array antenna constructed by arranging dipole antennas was described, but the present invention can be applied to antennas for transmitting and receiving various polarized waves by using elements for vertically polarized waves or circularly polarized waves. It is also possible to configure

[Second Embodiment of the Invention] A second embodiment of the invention will be described below with reference to FIG. Figures (a) and (b) are a front view and a side view showing the configuration of a broadside array antenna according to a second embodiment of the present invention. Broadside as shown in the figure.
The array antenna 11 consists of three parasitic elements and two feeding elements, and the elements are arranged alternately. and a distance S from the antenna element perpendicular to the radiation direction of the antenna.
A reflector plate 12 is attached across the space. This reflector 1
2 has an area larger than the opening area of the antenna 11,
It is composed of a metal plate or metal mesh.

By attaching this reflector plate 2, the broadside array antenna 11 becomes unidirectional.

In the above configuration, the distance S between the element and the reflecting plate is S
-λ/4, 3λ/4, the antenna gain when the element length and element spacing are set as shown below is shown in Figure 4.
The case of λ/4 is shown by a Δ mark, and the case of S-3λ/4 is shown by a 0 mark.

When S-λ/4, in the case of 3 elements, l! l/no 0.92, d, #'-3,
In the case of 25 elements, ノ, /no 0.92, d1/l! -3
, 4, 1'2/ノ 0.92, d2/l! In the case of 3,87 elements, No.17 No.0.88, dx/i-3,6 No.2
/No 0.90, d2/l'-3,8I! 37 no 0.
92, ds/no 3,8S-3λ/4, in case of 3 elements, Is/l-0,90, dt/no 3.0
In the case of 5 elements, no1/no0.90, di/, ff-3
,012/J! -0,94, d2/no 3.87 element, no 1/no 0.90, d1/no 3.012/no ■ 0.94, d2/no rumor 3.8' no 3/no 0696,
d3/no 4.0 Further, FIG. 6 shows the directivity characteristics of the above-mentioned broadside array antenna consisting of five elements in the case of S-3λ/4. FIG. 6(a) shows the horizontal plane directivity of a plane cut horizontally through the dipole, and FIG. 6(b) shows the vertical plane directivity of a plane cut vertically through the center of the dipole.

By attaching a reflector in this way, a broadside array antenna composed of any number of antennas can be used as a fourth antenna.
As shown by the Δ and 0 marks in the figure, the gain is improved, and it also functions as a unidirectional device, allowing efficient radiation with low side lobes. .

Note that for antennas with configurations of 3 and 5 elements, there are values in which the aperture efficiency exceeds 100%, but this is because the aperture area is calculated as element length x strand spacing, and the effective area is calculated to be small. This is because

Furthermore, in order to further increase the gain of the above antenna, broadside array antennas configured with the antenna element length and element spacing set to the values set above can be arranged vertically, left and right, and power is fed to each antenna in parallel. This can be achieved by In this case, the directivity can further reduce the side lobe level by considering the arrangement of each antenna.

In the above embodiment, the reflector plate 12 is made of a metal plate or metal mesh, but by installing the antenna so that the concrete or mortar wall used for the wall of a building serves as a reflector, it can be made similar to the above embodiment. effect can be obtained.

[Effects of the Invention] As described above, according to the present invention, the feed element and the parasitic element are arranged at intervals of 0.5 to 1 wavelength, and the configuration is such that a radiation current flows through the parasitic element due to mutual induction. This reduces the number of power feeding points to the broadside array antenna, simplifies the configuration of the antenna, and reduces costs.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a broadside array antenna consisting of three elements according to the first embodiment of the present invention, and FIG.
The figure shows a broadside device consisting of five elements in the same example.
FIG. 3 is a diagram showing the configuration of a broadside array antenna consisting of seven elements in the same embodiment. FIG. 4 is a diagram showing the relationship between element array area and gain. 6 is a diagram showing the configuration of a broadside array antenna equipped with a reflector according to a second embodiment of the present invention, and FIG. 6 is a diagram showing the directivity characteristics of the broadside array antenna. 1.2.3... Antenna element, 11... Broadside array antenna, 12... Reflection plate. Applicant's agent Patent attorney Takehiko Suzue (a) (b) Figure 1 Figure 1I2 Figure 3

Claims (2)

[Claims] (1) A broadside array antenna characterized in that a feeding element and a parasitic element are arranged at intervals of 0.5 to 1 wavelength, and a radiation current flows through the parasitic element by mutual induction. (2) The broadside array antenna according to claim 1, further comprising a reflector for obtaining unidirectionality in parallel to the arrangement direction of the feed elements and parasitic elements.