JPS6181003A - Array antenna - Google Patents

Abstract

PURPOSE:To obtain an array antenna of good electric characteristics without degrading the antenna efficiency by setting the excitation phase distribution of element antennas to a polygonal line and making the radiation pattern asymmetrical. CONSTITUTION:Phase adjusters 3a-3n connected to element antennas 1a-1n are used to adjust a phase phiX of input signals of element antennas 1a-1n on a basis of the center of the array antenna. If a position P of a maximum phase quantity is smaller than 0.3, the value which a maximum phase quantity phiM can take is <=15 deg., and the improvement factor of the side lobe level is about maximum 4dB, and therefore, the array antenna is not suitable for practical use experimentally. If the position P of the maximum phase quantity is larger than 0.7, the improvement factor of the side lobe level is degraded and the gain is reduced according as the position P of the maximum phase quantity is made larger, and therefore, the array antenna is not suitable for practical use experimentally. Thus, the range of the position P of the maximum phase quantity is limited to 0.4<=P<=0.7.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a six-array antenna having a plurality of element antennas. [Prior Art] Fig. 1 is a diagram showing a conventional array antenna.

In FIG. 1, (1a) to (1n) are element antennas.

(2) is handled by a power divider.

Conventionally, in this type of antenna, the amplitudes of the element antennas (1a) to (1n) are set by the power divider (2) and the phases are made equal in the shape of the radiation pattern. For this reason, the influence of reflections from the ground, sea surface, etc. is small (in order to reduce the side lobe level of the array antenna described above), setting the amplitude of the element antennas (1a) to (1n) will reduce the effect of the antenna. (For example, the effect of a sidelobe level of -30 dB is approximately 85 cm, which is -4 D dB.
However, there is a drawback that the effectiveness of this method is approximately 70%.

[Summary of the invention]

This invention was developed to improve these conventional problems, and improves antenna efficiency by setting a phase in the element antenna that makes the radiation pattern asymmetric and reduces the side lobe level on one side. The present invention provides an array antenna with good electrical characteristics without deteriorating the electrical characteristics.

[Embodiments of the invention]

FIG. 2 is a diagram showing an embodiment of the present invention.

In FIG. 2, + (1a) to (1n) are element antennas.

(2) is a power divider, and (3a) to (3n) are phase adjusters.

FIG. 3(A) shows the element antennas (1a) to (In
) in FIG. 3 is the excitation phase.

However, the position of the element antenna with respect to the array antenna is normalized by the array antenna length.

As shown in Figure 3 (J3), element antennas (1a) to
The phase adjuster (5a) to which the phase φ(x) of the input signal of (1n) is connected to the element antennas (1a) to (1n)
(3n), with the center of the array antenna as the base bubble, tune = hE as shown in equation (1)〇However, (6Ml- is the maximum phase amount, P is the maximum phase amount φM) Positions W and X are the positions on the array antenna.

Radiation of array antenna/kuturn E (u)
is expressed by equation 12).

+ However, A(x) is the excitation and removal width of the element antenna, u = 2π
The ground is θ/λ (λ is the wavelength used).

FIG. 4 shows an embodiment according to the present invention.

Excitation amplitude A (x) of element antennas (1a) to (1n)
The maximum phase amount φM of the excitation phase φ(x) and the maximum phase amount of which the sidelobe level when given by It shows the relationship between the position P and the position P of the maximum phase amount.
(In the case of 0, 3, the calculation result of Equation 21 shows that the possible value of the maximum phase amount φ base is 15 degrees or less, and the sidelobe level improvement is at most 4 dB 8 degrees. From experience, it is not suitable for practical use.Also, if the range of the maximum phase amount [P is P>07, increase the maximum phase amount cp (as the degree of improvement in the sidelobe level decreases and the gain also decreases). Therefore, it is a theory suitable for practical use based on experience.For the above reason, the possible range of the maximum phase amount ET'P in equation (3) is limited to 0.3≦P≦07.

In FIG. 5, the maximum phase amount φM is 35' based on equation (3).

This is a discussion to compare the radiation patterns of the case where the position P of the maximum phase amount is given an excitation phase φ(x) of 0.575 and fc and the conventional case where an equal phase distribution is given and fC. Radiation pattern b is a conventional radiation pattern.

If the above method Vcz fl is used, as shown in Fig. 5, the sidelobe level on the side affected by reflection from the ground, sea surface, etc. can be greatly improved without reducing the effectiveness of the antenna. Performance can be obtained.In the above explanation, we have focused on the linearly arranged array antenna shown in Fig. 2, but when the array antenna is arranged in one plane,
The same implementation is possible for case c.

In addition, in the embodiment, the element antenna (1) and the power divider 12
), but this can also be implemented by changing the length of the line between the element antenna and the power divider.

[Effects of the Invention] - As explained above, according to the present invention, by setting the excitation phase distribution of the element antenna in a polygonal manner and making the radiation turn asymmetrical, antenna efficiency can be prevented from decreasing (electrical This has the effect of realizing an array antenna with good characteristics.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional array antenna, Fig. 2 is a block diagram of an embodiment of a 7-ray antenna according to the present invention, and Fig. 3 (A) shows the excitation amplitude in the array antenna according to the present invention. Figure 3, Part 1 (B) is a diagram showing the oscillation phase of 1 or more in the array antenna of the present invention, and Figure 4 is a diagram showing the maximum phase amount of the excitation phase and the position r of the maximum phase amount in the array antenna of the present invention. Diagram showing relationships. FIG. 5 compares the directivity characteristics of the array antenna according to the present invention and the conventional array antenna. In the figure, (Ia) to Nn) are h-element antennas, (2) is a power divider, and (3a) to (3n) are phase=X devices. Note that in FIG. 1, the same or corresponding parts are designated by the same reference numerals.

Claims (2)

[Claims] (1) In an array antenna equipped with a plurality of element antennas and a power divider that distributes power to each element antenna,
An excitation phase φ_M (x+1)/(1-p)(
−1≦x≦−p), −φ_M/p(−p≦x≦p), φ
_M(x-1)/(1-p) (p≦x≦1) [where x is the distance on the antenna normalized by the array antenna length, φ_M is the maximum phase amount, and p is the position of the maximum phase amount. ] An array antenna characterized by being provided with phase adjustment means for setting. (2) In the above excitation phase, the range of the maximum phase amount φM is 35P-5≦φ_M≦210P-50 (0.3≦P≦0
．． 7) The array antenna according to claim (1), characterized in that: