JPS58182305A - Antenna for circularly polarized wave - Google Patents

Abstract

PURPOSE:To generate a circularly polarized wave with high accuracy, without any limination of the selection of feeding point and the exciting method, by correcting a cross angle electrically with a prescribed phase difference of feeding voltages (or currents) for two straight polarization wave exciting antennas. CONSTITUTION:Two dipole elements DP1, DP2 are provided at an angle theta not being 90 deg. so as to be crossed in two-dimension, and electric fields E1, E2 radiated from the dipole elements DP1, DP2 are crossed at the angle theta in two-dimension. Thus, through the method exciting the antennas, a dextrorotatory or a levorotatory polarization wave is obtained. The dextrorotatory polarized wave is generated by giving a delay of (theta+ or -x) to the phase of a voltage (or current) fed to feeding points f1, f1' of the DP1 from that fed to feeding points f2, f2' of the DP2, and the levorotatory polarized wave is generated by giving a lead of (theta+ or - x) inversely, allowing to obtain a desired circularly polarized wave.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a circularly polarized antenna that generates circularly polarized waves using two linearly polarized (including elliptically polarized) excitation antennas.

[Technical background of the invention and its problems] Conventionally, in this type of circularly polarized antenna, the directions of electric field vectors excited by two linearly polarized wave excitation antennas are orthogonal to each other, as shown in Fig. 1. There was a membership fee. That is, circularly polarized waves were obtained by exciting two linearly polarized wave excitation antennas so as to satisfy the condition of E y = Eze th' T (2) under the excitation condition of .

However, in the above equations (1) and C), El and EsFi are the vector quantities of the electric fields radiated from the Guiball elements DPI and DP2, respectively, Ex and Ey are the radiated electric fields in the X direction and y direction, respectively, and X, △ and y are They are unit vectors in the X direction and the y direction, respectively. In this case, the combined radiated electric field is 7=f+1''Ex(Q+ethj29), and it can be seen that circularly polarized waves are certainly excited.

In the table and Figure 1, points fl, fl' and point f
2. f2' are dipole elements DPI and DP, respectively
This is the second power feeding point.

By the way, in such conventional circularly polarized antennas, as mentioned above, it is essential that the directions of the excitation polarized waves are orthogonal to each other, so there is freedom in how to choose the feed point and the excitation method. This sometimes caused major inconveniences in terms of design.

[Purpose of the invention]

- This invention was made in view of the above circumstances, and it is an object of the present invention to provide a circularly polarized antenna that can generate highly accurate circularly polarized waves without imposing any physical restrictions on the method of selecting a feeding point or the excitation method. purpose.

[Invention 11! In other words, in this invention, the direction of the electric field radiated by two linearly polarized wave excitation antennas is not limited to 90 degrees, that is, two-dimensional and three-dimensional intersect at any suitable angle convenient for the design. This crossing angle is electrically corrected by a predetermined phase difference between the voltages (t or currents) respectively fed to the two linearly polarized wave excitation antennas to obtain circularly polarized waves. , Specifically, when the intersection angle of the above electric fields viewed from the direction perpendicular to the circularly polarized wave to be obtained is θ, the phase difference between the powers to be supplied to each of the above is (θ±π).
shall be.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a circularly polarized antenna according to the present invention will be described in detail according to embodiments shown in the accompanying drawings.

#! FIG. 2 shows an embodiment of the arrangement of elements of a circularly polarized antenna according to the present invention, and for convenience of explanation,
Similar to the antenna shown in Figure 1, two dipole elements DP
This arrangement is shown for the case where I and DP2 are used. In addition, point fl.

fl' and point f2. As mentioned above, f2' is the feeding point of dipole elements DPI and DP2, respectively.

In this embodiment, as shown in FIG. 2, two dipole elements DPI and DP2 are arranged to intersect two-dimensionally at an angle of 0 that is not 90 degrees, and these dipole elements DPI and DP2 emit radiation. The electric fields E1 and E2 also intersect two-dimensionally at an angle θ. Therefore, if the dipole element DPI (the radiation electric field Es) is taken on the X axis, the radiation electric field E of this dipole element DPI is expressed as El = E, ・X (4) , the radiation electric field E of one dipole element DP2
gH=g2amθ・x 1E 2 sinθ・y
It is expressed as (5). However, El and E are dipole elements DPI and DP2, respectively, as described above.
represents the vector quantity of one electric field radiated from ]Thl
and E represent the complex quantities of these electric fields.

△ Also, X and y are the nine ways described above, respectively
Represents a unit vector in the direction.

Therefore, in this case, the X component ix and the y component iy of the combined radiated electric field are shown in Figure 2 so as to satisfy, for example, -j (θ±1c) E1=E2e (7). If the antenna is excited, the above equation (6) becomes as follows, so a right-handed circularly polarized wave can be obtained, and the antenna must be excited so that it satisfies the following: (#±x) 1, = EEl (9) Since the above equation (6) becomes as follows, it follows that a left-handed circularly polarized wave is obtained.

As is clear from equations (6) to (10) above, the second
Each feeding point f1. of the 92 dipole elements DPI and DP2 shown in the figure. f1' and f2. If voltages (or voltages R) having a phase difference (θ±π) with respect to f2' are supplied from a power supply device (not shown), a desired circularly polarized wave can be obtained, and the power supply point fl of the dipole element DPI, fl
' The phase of the voltage (t or current) fed to the dipole element DP2's feeding point f2. If the phase of the voltage (or electric power fi) supplied to f2' is delayed by (θ±π), a right-handed circularly polarized wave will be generated, and if it is delayed by the reverse K (a±π), a left-handed circularly polarized wave will be generated. do.

In addition, in the circularly polarized antenna according to the present invention, the electric field crossing angle 0 described above can be set arbitrarily, and can be set as desired depending on the surrounding environment of the antenna or according to design convenience. You can set it to a value.

Furthermore, it goes without saying that the circularly polarized antenna according to the present invention is not limited to antennas having the same phase center as shown in FIG. It can also be effectively applied to different paired elements.

In other words, in the case of the antenna shown in Fig. 3, two dipole elements DPI and DP2 are arranged three-dimensionally with their phase centers different from each other.
When looking at this antenna from the axis direction, it is three-dimensional and Fi
However, the electric fields E and E2 radiated by these dipole elements DPI and DP2 also intersect at an angle θ, and if circularly polarized waves are to be generated in the direction parallel to the z-axis, then the All formulas (4) to (10) shown in (4) to (10) are applied.

Therefore, the feeding points fl, fl' and f2 of the two dipole elements DPI and DP2 shown in FIG.
．． A desired circularly polarized wave is generated in a direction parallel to the z-axis by supplying voltage (or current) having a phase difference (θ±π) to f2′ from a power supply device (not shown). In this case, the above electric field crossing angle 0Fi is the angle of the radiated electric field by the two dipole elements DPI and DP2 when viewed from the direction perpendicular to the circularly polarized wave to be obtained.
If the above-mentioned crossing angle θ when viewed from any direction is determined and the above-mentioned power feeding is performed, it is possible to generate a desired circularly polarized wave in any direction not limited to the direction parallel to the direction i.

Furthermore, it goes without saying that the circularly polarized antenna according to the present invention is not limited to the above-mentioned antenna composed of nine dipole elements, but is of a type that obtains circularly polarized waves using two linearly polarized wave excitation antennas. It can be applied to all antennas.

Friend, the linearly polarized waves in the above explanation include elliptically polarized waves in a strict sense. Therefore, it goes without saying that the present invention may use an elliptically polarized wave excitation antenna.

〔Effect of the invention〕

As explained above, according to the circularly polarized wave antenna according to the present invention, the directions of the electric field vectors excited by the first and second linear or elliptically polarized wave excitation antennas do not need to be orthogonal to each other. Since circularly polarized waves can be obtained, the degree of freedom in selecting the feeding point and the excitation method is greatly improved, and flexibility can be provided in the design.

In particular, it is of great significance to employ the circularly polarized antenna according to the present invention in areas where space for installing antenna elements is limited.

[Brief explanation of drawings]

Fig. 1 #i is a plan view showing the arrangement of elements in a conventional circularly polarized antenna using two dipole elements, and Fig. 2 shows a circularly polarized antenna according to the present invention using two dipole elements having the same phase center. Figure 3 is a plan view showing an example of the arrangement of elements when applied to an antenna using the present invention. FIG. 7 is an elevational view showing an example of the arrangement of elements in the case of the present invention. DPI, DP2...dipole element, fl, f1'. f2. f2'-Feed point Figure 1 V? Figure 3

Claims (1)

[Claims] A circularly polarized wave is generated in the predetermined direction by feeding power with a phase difference (θ±π) to the first and second linearly or second linearly polarized wave excitation antennas arranged so as to have a phase difference (θ±π). Circularly polarized antenna.