JPS61136305A - Antenna - Google Patents

Abstract

PURPOSE:To obtain a single directivity which has suppressed a side lobe by constituting a feed of linearly arranged three elements, of a tournament connection of two stages of a 3dB coupler. CONSTITUTION:Element I-IV and an element O are installed at an interval of 90 deg. on the periphery, and in the center of a circle, respectively, and at every bearing, linearly arranged three elements centering around the element O are utilized. A signal of the element I receives a variation of an amplitude and a phase of 1/2 by a 6dB attenuator, and -j/2<1/2> each by coupling of (2) and (4) of a 3dB coupler H3 and (3) and (1) of a 3dB coupler H1, and becomes and output of -1/4 in a terminal x+. In the same way, an output of 1/4 is obtained from the element III. A signal of the element O receives an amplitude variation of 1/2<1/2> each by two-distributors S1, S2, but an output of the two- distributor S2 is synthesized again, therefore, an output of -j/2 is obtained in the x+ terminal. Accordingly, when feed is executed from the x+ terminal, outputs of the element I, O and III become 1:j2:-1 from a reciprocal theorem of an antenna, and their composition becomes a single directivity. Also, when the 3dB coupler is made to have a wide band characteristic, a wide band is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] ' The present invention relates to a directional antenna, and in particular to a directional antenna consisting of a central element, an array antenna with four elements arranged in a circle, and a feeding circuit, and having four feeding points. This invention relates to a four-beam antenna for radio wave direction detection, which can radiate radio waves in directions different by 90 degrees in the horizontal plane when power is supplied from each of the four beams.

[Conventional technology]

Various methods can be considered for the purpose of realizing a 4-beam antenna that can radiate radio waves in 90° different directions in the horizontal plane, but the simplest method is to use 4 types of small directional antennas. They are arranged in different directions by 90".

However, in order to use a 4-beam antenna for radio wave direction finding on aircraft, etc., it is required to be small and lightweight, and the combination of 4 types of small directional antennas is difficult to meet. Because of this, it is usually not practical.

Therefore, as shown in FIG. 3, the radiating element 0 is placed at the center 0, and the radiating element 2 is placed in the X direction on the circumference of the 17th plane with radius R centered at 0.

(1), and radiating elements ff and IV in the y direction, and appropriately excite these five elements to generate radiation in four directions: the positive and negative directions of X and the positive and negative directions of y. It is possible to do so. In this case, several types of power feeding excitation methods for the five elements are conceivable, but for radio wave direction detection, at least the following three conditions must be satisfied.

(11 directivity is a small directivity and must not have high level side lobes. (Normally, side lobes are 12
It is required that it be 0 dB or less. ) (2) It has four feeding points, and when feeding from each, radiation directivity in four directions differing by 90° (in the horizontal plane) can be obtained.

(3) Item (1) (21) above shall hold true over as wide a frequency range as possible. (The frequency range is expressed as a multiple of the ratio between the upper limit frequency and the lower limit frequency at which good characteristics can be obtained. Figure 4 shows an example of such a feeding excitation method, in which the radio waves emitted from each radiating element are in the same phase in the direction in which the radiation beam is aimed. A case is shown in which an additive synthesis method is used in which power is supplied in an additive manner, where ■ is a power supply and 2 is a three-way divider.

In the case of FIG. 4, radiating elements I and III are arranged on the X-axis, and radiating element 0 is located at the origin. The power from the power source 1 is divided into three parts by the three-way divider 2, each having a length It
The elements I, 0 . I [Guided by I. At this time, the ratio of the excitation amplitude of each element is 1=21
It is assumed that the three-way divider 2 is made so that

Now, if the origin is the phase reference point, the excitation phase of each element is -β(j'l-j!o), o, β(io-
j! 2) is given. However, β-21-Ke is a propagation constant of radio waves in the feed line, and λ=free space wavelength, ε2-equivalent relative dielectric constant in the feed line. Here, as the feeder line, one that propagates in T8M mode and does not have frequency dispersion characteristics is considered.

The radiation field in the xy plane in this case is given by the following equation.

E(φ, = , j(kRuatl-J(L-1-))
・2...-1"'°"p-p<1"-"' -(1
)However, in order to consider that the waves from each wave source are added in phase in the positive direction of the large X-axis (the direction of φ-0), the wave in the direction of φ=0= Let's examine the phase relationship. Now, if we set φ−0 in equation (1),
Element 1. The phases of the waves radiated from O and III are kR-β(11-1o)=斐(R-凰(' r
-' o) ) , 0 , (k R-β(10J 2>
>-27 [-(Rq Otsu(l.

Enter 1! It can be seen that z)). It can be seen that if the length of the feeder line is determined to satisfy the following, the waves of each element are added in the same phase in the φ-0 direction. The radiation directivity at this time is (11, (from equation 21, E(φ) = cos2 (
kRsin2-') - (3). Just 3)
The formula is normalized so that the maximum value is 1.

FIG. 5 shows the results of calculating the radiation directivity using equation (3) using kR as a parameter.

From this, it can be seen that a small directivity is obtained near kR=90°, and as the frequency becomes lower (kR becomes smaller), the beam width becomes larger and the level of backward radiation becomes higher. Also, when kR becomes larger than 90°,
It is observed that as the beam width becomes smaller, the backward radiation becomes a side lobe. Now backward (φ=180°
Assuming that the radiation level in the direction of
It can be seen that 71.57=1.52 times is obtained. A frequency range of 1.52 times is an unsatisfactory value for the above-mentioned wideband requirement, and therefore an antenna with desired characteristics cannot be realized by the additive synthesis method.

FIG. 6 shows another example of the feeding excitation method, in which a canceling combination method is used to cancel and suppress backward radiation, and 3 is a two-way divider.

In FIG. 6, a two-element model is shown, and it is assumed that the two-element divider 3 is an equal divider, and elements (2) and (2) are excited with equal amplitude. In this case, radiation β(1-fan) = 2 cos (k Rcos φ--) (4)
is required.

In order for the backward radiation to be zero, in equation (4), kR + Muhi ω = ± ball - (5) Z
2 should hold true. Since equation (5) cannot be established for all frequencies, if it is established for the wavelength λ0, then 1<l z-1+) = 2RT-λL −・(
6) Get or. In other words, I! satisfies equation (7). ,,1
If 2 is selected, it is possible to achieve upward movement of the vehicle at the wavelength λO.

ωo = (61 or the angular frequency at which equation (7) holds true. Equation (8) is normalized to be 1 at φ-〇°. The numerator of equation (8) is = ko (ω-ωo)
, it can be seen that when φ=0°, the condition is 2R large for a simple change. The results of calculating the radiation directivity at this time are shown. It can be seen from this that when using the cancellation synthesis method, the frequency range is approximately 95/85=1.12 times, which is a very narrow band. Also, contrary to the additive synthesis method, the beam width becomes wider as the frequency is higher (kR is larger), whereas the beam width becomes narrower on the lower frequency side and side lobes also occur.

FIG. 8 shows still another example of the power feeding excitation method, and shows a case using a two-directivity superimposition method in which two directivities are superimposed to form an upward direction toward the vehicle.

As shown in FIG. 8, radiating elements 1. O
, III, and excite elements (2) and (2) with the same amplitude of 1 and opposite phases, a figure-eight radiation directivity is obtained in which maximum radiation is radiated in the positive and negative directions of the X-axis. Combining this with the directivity (omnidirectionality) of element O excited with an amplitude of 2 and a 90° phase advance, we get
Since radiation in the positive direction of the axis is strengthened and radiation in the negative direction is weakened, an antenna that can be directed upwards of the vehicle is obtained. This method of obtaining vehicle upward direction has been known for a long time as an antenna for radio wave direction finding in a relatively low frequency band, which combines the figure-8 directivity of a loop antenna and the omnidirectionality of a unipole antenna. ing. The well-known Atcock antenna is also one of this type.

Here, we will consider what the frequency characteristics of the radiation directivity will be, assuming that the excitation conditions shown in FIG. 8 are satisfied regardless of the frequency.

The directivity due to elements ■ and ■ is j0 ftFtcm fe −e = j 2 sin (kRcosφ”)
−(10) is given. The directivity of element 0 is j2
Therefore, the overall directivity is E(φ) = 32 (1+ sin (kRcos
φ)) (11) is given. This is normalized so that it becomes 1 when φ=0.

Figure 9 shows the calculation result of directivity using equation (12), from which the band is approximately kR = 54.9° to 100°,
It can be seen that a multiple of about 100154.9=1.82 can be obtained. This value has a wider band than 1.52 times the additive synthesis method, and has the advantage that the directional beam width is also almost constant. Note that all of the above calculations assume that the excitation conditions shown in FIG. 8 hold regardless of the frequency.

[Problem that the invention seeks to solve]

In order to realize a four-beam antenna in this way, the most desirable result can be obtained by using the two-directivity superimposition method. However, in this case, it is necessary that the excitation amplitude phase relationship as shown in Fig. 8 be established regardless of the frequency, and in order to switch the beam direction, the complex excitation amplitudes of elements It needs to be replaced. Furthermore, element row II on the y-axis, 0. Similar excitation needs to be performed for N (see FIG. 3), but no power supply circuit has hitherto been known that satisfies this requirement.

The present invention aims to solve these problems of the prior art.

[Means for solving problems]

The antenna of the present invention has an antenna system consisting of five elements, elements I to ■ arranged on the circumference and element O arranged in the center, and when an input of amplitude 1 is applied from the first terminal, the second A 3dB coupler that generates a 1/, l output at the terminal and a -jl/α output at the third terminal, and
．． A 2-way divider that divides the input into two and outputs it to the third terminal.
The antenna elements I, I[[.

II and IV are each passed through a 6dB attenuator to the third
, 4th. 7th. connected to the second terminal of the eighth 3dB coupler; 4th. 7th. The first terminals of the eighth 3dB couplers are respectively connected to the second terminals of the eighth 3dB couplers. 1st. 6. Connect the antenna element O to the second terminal of the fifth 3 dB coupler, connect the antenna element O to the first terminal of the first two-way divider, and connect the second terminal of the first two-way divider to the second terminal of the first two-way divider. the third terminal of the first two-way divider is connected to the first terminal of the third two-way divider; 2. a third terminal and a second terminal of a third two-way divider; the third terminal respectively.
4th. 7th. and the third terminal of the eighth 3dB coupler. 4th. The fourth terminals of the 7th and 8th 3dB couplers are respectively connected to the 1st and 2nd terminals. Fifth. 6th 3dB
the third terminal of the coupler and the first. Second. Fifth. 6th
Power is supplied from the first terminals of the 3 dB couplers.

[For production]

According to the antenna of the present invention, the element (2) on the X axis.

Regarding ■, the excitation amplitude phase relationship shown in Fig. 8 based on the °ζ2 directivity superposition method can be established regardless of the frequency, and in order to switch the beam direction, in Fig. 8, the relationship between element Since the complex excitation amplitude can be exchanged and the same excitation can be performed for the element rows n, O, ■ (see FIG. 3) on the y-axis, the antenna element I.

■Positive direction and negative direction in the direction connecting the antenna element IV
, ff can be obtained in the positive and negative directions.

〔Example〕

FIG. 1 shows the configuration of a system consisting of an antenna and a feeder circuit in one embodiment of the present invention.

In the same figure, H1 to H8 are 3dB couplers, S1 to S3
is a 2 divider, A1-A4 is a 6 (IB attenuator, and O
~■ are the same antenna elements as shown in FIG.

Furthermore, FIG. 2 shows an example of the configuration of each element in the feeder circuit shown in FIG. It is coupler H.

The 3dB coupler H has an input/output relationship as shown in Fig. 2 (C), and has four terminals ■ to ■.For example, when an input having a magnitude of 1 is applied to terminal ■, terminals ■ and ■ The output from the terminal (2) is delayed in phase by 90 degrees with respect to the output from the terminal (2). Therefore, the output to terminal ■ is n
・If it is (the electric power is expressed as 〇, so if it is expressed as a voltage or current wave, it becomes yu), the output to terminal ■ becomes -'' 　.

The 3dB coupler H is a symmetrical circuit, and if an input of 1 is added to the terminal ■, an output of U will be generated at the terminal ■, and -JV will be generated at the terminal ■.
produces an output of T. Similarly, if an input of 1 is applied to the terminal (2), an output of n= will be generated at the terminal (2), and an output of -jJT will be generated at the terminal (2). Furthermore, if an input of 1 is applied to the terminal (2), an output of 1 is generated at the terminal (2), and an output of -'' is generated at the terminal (2).

Furthermore, as shown in Figure 2(b), the two-way divider S produces outputs that are equally distributed between the second and third terminals when an input of magnitude 1 is applied to the first terminal. , so the voltage or current outputs of the second and third terminals are both drained. The 6 dB attenuator A has an input with a magnitude of 1 at the first terminal.

Now considering the case of reception in the system shown in Figure 1, a signal with an amplitude of 1 received by antenna element
It passes through to produce an output on amplitude, and is input to the terminal (2) of the 3 dB coupler H3, producing an output multiplied by -35 at the terminal (2). This output is input to the terminal ■ of the 3dB coupler H1,
Terminal ■ becomes the first king.

Also, the signal with amplitude 1 received by element ■ is applied to terminal ■ of 3dB coupler H4 via 6dB attenuator A3, and is applied to terminal ■ of 3dB coupler H4.
The output of the terminal ■ of the B coupler H4 is applied to the terminal ■ of the 3 dB coupler H1, producing an output at the terminal ■ of the 3 dB coupler H1. Therefore, the output at terminal ■ is ・ (−)・
(L)=upper Tα σ+.

On the other hand, the signal received by element 0 is divided into two equal parts by a 2-way divider S1, and added to each 2-way divider S2 and 33 to further divide the signal into two parts.
Equally divided into 3dB couplers H3, H4, H7,
It reaches terminal ■ of H8. 2 divided into 2 by 2 divider S2
One of the paths is 2 distributors S1, 2 distributors S2, 3d
B coupler H3 terminal ■ and terminal 0 question and 3dB coupler H
It passes between terminal ■ of terminal 1 and terminal 0, and its transmission coefficient is < -L > ・(1)・(author)・(
-jIT J': , /T)=-jI. The other route passes through the 29 splitter S1, the 2 splitter S2, the terminal ■ of the 3 dB coupler H4 and the terminal 0, and the one between the terminal ■ of the 3 dB coupler H1 and the terminal 0, and its transmission coefficient is (-L )・(2)・(
-j-L)・(axe)7,'6=-J-, so the transmission coefficients of both paths are + equal. Therefore, the signals on the two paths from element 0 to terminal ■ of 3 dB coupler H1 are added in phase, so -
jI +”li 1=-j-4- is the element
This is the signal output to terminal X+ when a signal with amplitude 1 at 1 + 0 is received.

Conversely, if we consider the case where power is fed from terminal X+, the reciprocity theorem shows that antenna element I, 0. The complex excitation amplitude distribution (relative value) at I[[ is −, −j±・middle
2.

1' = 1 : j 2 : -1, and it is possible to realize the excitation in the case of obtaining unidirectional radiation in the positive direction of the X-axis as explained in FIG.

By making similar considerations, by feeding power from the X-terminal, y-terminal, and y-terminal in Figure 1, it is possible to supply power in the negative direction of the X-axis, the positive direction of the y-axis, and the negative direction of the y-axis, respectively. Excitation when obtaining directional radiation can be realized.

In the above explanation, 3dB coupler H, 2 minutes
.

Although phase changes due to the lines connecting circuit elements such as the device S are ignored, in reality, the line length must be selected so that the phase changes due to the lines passing through are the same no matter which route is taken. There's no need to say that.

From a practical standpoint, instead of 6dB attenuator A, use a 6dB coupler with output coupling degrees of 6dB and 1.25dB (connect the 6dB coupling terminal side to the antenna side).
, 1.25 dB It is preferable to use the output to the coupling terminal side for various purposes.

Next, to explain the feasibility of wideband circuit components, the phase difference between the outputs to the two output terminals is .

It is known that a 3 dB coupler of 90' regardless of frequency can be realized by a symmetric distributed coupling type 3 dB coupler. As for the degree of coupling, it is known that a substantially constant value can be obtained over a range of frequency ratios of 10:1 or more. In this way, a desired 3 dB coupler with practically sufficient performance can be realized.

The broadband property of the distributor results in the broadband property of the impedance transformer. For example, considering a 2-divider, 10
If you make a wideband impedance transformer from 0Ω to 50Ω and connect the 100Ω side in parallel, both the input and output will be 50Ω.
A broadband two-way divider of Ω is obtained. There are many reports on broadband impedance transformers, and they are possible.

Furthermore, with regard to attenuators, means for realizing an attenuator that can be practically considered to have no frequency characteristics are well known.

As explained above, the embodiment shown in FIG. 1 is constructed by a combination of components whose broadband properties have been confirmed, and its feasibility is guaranteed.

1) L, Young+” The analysis
cal equivalence of TEM-mod
Directional Couplers an
d transmission-1ine step
ed-impedance filters”, Pr
oceedingsof 1. E,E,,Vol,1
10. No. 2.1) I) 275-281. Feb, 1
963゜2) For example, W. Kammler, "T
he Design of DiscreteN-Se
ction and Continuously Ta
pered Symmetrical Microwav
eTf! M Directional Couple
ers” +IEEETransaction on
Microwave Theory and Tec
hniques.

Vol, MTT-17, No. 8. pp577-590
．． Aug, 19693) For example, R, W, 1 opfen
stein, ”A TransmissionLi
ne Taper of Improved Desi
gn,” IRE, Vol, 44゜pp539-5
48. April 1965 [Effects of the Invention] As explained above, according to the antenna of the present invention, in an antenna system consisting of five elements, elements I to IV arranged on the circumference and element 0 arranged at the center, the antenna Element T
It is possible to obtain unidirectional radiation directivity in which side lobes are sufficiently suppressed in the positive and negative directions in the direction connecting antenna elements ■ and ■, and in the positive and negative directions in the direction connecting antenna elements Good characteristics can be obtained over a frequency range.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an embodiment of the present invention, Fig. 2 is a diagram showing an example of the configuration of each element in the feeder circuit shown in Fig. 1, and Fig. 3 is a diagram showing the arrangement of elements in a 4-beam antenna. Figure 4 is a diagram showing a power supply excitation method using the additive synthesis method.
Figure 5 is a diagram showing the radiation directivity by the additive combination method, Figure 6 is a diagram showing the feeding excitation method by the cancellation combination method, Figure 7 is a diagram showing the radiation directivity by the cancellation combination method, and Figure 8 is a diagram showing the radiation directivity by the cancellation combination method. FIG. 9 is a diagram showing the excitation amplitude phase in the bidirectional superimposition method, and FIG. 9 is a diagram showing the radiation directivity in the bidirectional superimposition method. A, At~A 4-6 d B attenuator, S, 31~53
-2 distributor, H, H1 to H8 to 3dB Cabrad - power supply, 2-3 distributor, 3-2 distributor Patent applicant Sumitomo Electric Industries Co., Ltd. agent Patent attorney Tamamushi Kugobe xi Figures H1 to H8- -----JO Mikado 77 Figure 2 (a) (b)
(c) Fig. 3 Fig. 0 to IV-A/Tenna element Fig. 4 Fig. 6 ■ Fig. 5 φ (deg) Fig. 7 g Fig. 7 Procedural amendment (method) (l. 1985 April/Z-day Mr. Manabu Shiga, Commissioner of the Patent Office
2. Name antenna of the invention 3. Relationship with the person making the amendment Patent applicant address 5-15 Kitahama, Higashi-ku, Osaka Name (21)
3) Sumitomo Electric Industries, Ltd. Representative: Tetsubu Yojo 4, Agent A., Shiba γ Date of dispatch: March 26, 1985 6. Subject of amendment: Detailed description of the invention in the specification. ) Page 20 of the specification, lines 2 to 13, “1)・-1
Delete 965J and correct it as follows °1)
Young, L., 'Analytical equi-individuality of TEM mode directional couplers and transmission line multistage impedance filters', Bros. Deindus on I. I., Vol. 110, No. 2, pp. 275-281, February 1963. (L, Young+“The analytical
Equivalence of TEM-mode
irectional Couplers and t
transmission-1ine stepped-
impedance filters'', Procee
dingsof 1. E, E,, Vol, 110. No
, 2. pp275-281. Feb, 1963)2)
For example, D., W., Kamura, “Design of N-stage and continuous Taber-type symmetrical microwave TEM directional couplers” 1. Iiii Transactions on Microwave Theory and Techniques. MTT-Vol. 17, No. 8, pp. 577-590, 196
August 9th (D, W, Kammlor, “The D
esign of Discrete N-5ecti
On and Continuously Taper
ed Symmetrical Microwave T
EM Directional Couplers'',
rEEETransaction on Micro
twave Theory and Technique
es. Vol, MTT-17, No. 8. pp577-59
0. Aug, 1969) 3) For example, R, W, Cloppenstein, “Improved Design of Transmission Line Taper Transformers,” IR, Vol. 44, 539.
-548 pages, April 1965

Claims (1)

[Claims] An antenna system consists of 5 elements, elements I to IV placed on the circumference and element 0 placed in the center, and when an input of amplitude 1 is applied from the first terminal, 1/√ is applied to the second terminal. 3 which generates an output of 2 and an output of -j1/√2 at the third terminal.
Connect the input of the dB coupler and the first terminal to the second and third terminals.
It consists of a feeder circuit equipped with a plurality of two-way dividers that divide the input into two parts and a plurality of 6dB attenuators that attenuate the input by half and output it, and antenna elements I, III, II, and IV each have 6 dB attenuators.
3rd, 4th, 7th, and 8th 3rd, respectively, through dB attenuators.
Connect to the second terminal of the dB coupler, and the third, fourth, and seventh
, connecting the first terminals of the eighth 3dB coupler to the second terminals of the second, first, sixth, and fifth 3dB couplers, respectively;
Antenna element 0 is connected to the first terminal of the first two-way divider, and the second terminal of the first two-way divider is connected to the first terminal of the second two-way divider.
the third terminal of the first two-way divider is connected to the first terminal of the third two-way divider, and the third terminal of the first two-way divider is connected to the first terminal of the third two-way divider;
the second and third terminals of the distributor and the second terminal of the third two-way distributor
, the third terminal is connected to the third, fourth, seventh, and eighth 3d terminals, respectively.
Connects to the third terminal of the B coupler, and also connects the third and fourth terminals of the B coupler.
, the fourth terminals of the seventh and eighth 3dB couplers are connected to the third terminals of the first, second, fifth and sixth 3dB couplers, respectively. By feeding power from the first terminal of either of the 3 dB couplers of An antenna characterized by obtaining directional radiation directivity.