JPH02174304A - Planer antenna - Google Patents

Abstract

PURPOSE:To expand the band width operated by a circularly polarized wave by arranging a subarray around a synthesis point of an array at an interval of 90 deg., rotating the physical attitude by pi/2 each sequentially and connecting lines whose length differs from lambdag/4 (lambdag is a wavelength of line) to a signal input output terminal of the array sequentially. CONSTITUTION:When an incident radio wave of subarrays 7A-7D is an elliptic polarized wave, the received radio wave of the subarrays 7A-7D is synthesized via lines 12-17 whose attitude differs sequentially from pi/2 each and whose length of line differs from lambdag/4, the attitude of the elliptic polarized wave of the radio wave coming from each subarray at the synthesis point differs from pi/2 each. Thus, the elliptic polarized waves whose attitude differs are synthesized, resulting that a completely circularly polarized wave is formed. Since the difference in the length of line from adjacent subarrays 7A-7D to the synthesis point is lambdag/4, the reflected wave coming from the synthesis point, inverted at the input and output point of each subarray and returned to the synthesis point has a different phase by 2pi each and the phase is inverted, then they are cancelled together. Thus, the frequency band width obtained at the circularly polarized wave characteristic is spread.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a directional planar antenna for microwaves, and in particular to a circularly polarized microstrip batch antenna for satellite broadcast reception.

<Prior Art> A planar antenna in which a large number of single-point-fed circularly polarized batch antenna elements of various shapes as shown in FIG. 3 are arranged on a planar dielectric substrate is known as a microstrip batch antenna.

As shown in FIG. 4, these batch antenna elements l,
2.3.4 are coupled to the input/output lines 5 in groups of four by appropriate coupling lines 6 to form a subarray 7. Arrows 8 indicate the physical orientation of the subarrays.As shown in FIG. 5, four such subarrays 7A, 7B, 7C17D are further connected to input/output lines 9 to form an array.

In FIG. 5(a), subarrays 7B, 7G, 7
D is in the same attitude as subarray 7A. The input/output line 9 is
It is connected to input/output point A of sub-array 7A via point P, point R, and 8 points, and to output point A of sub-array 7D via point P, point R, and point T, but is it a line? Since S+SA, RT+TD have the same length, subarrays 7A and 7D are excited in the same phase. Further, the input/output line 9 is connected to the input/output point B of the tour array 7B via the P point, the Q point, and the 0 point, and to the input/output point C of the subarray 7C via the P point, the Q point, and the 7 point, respectively. connected, line Q
U+UB and qv+vc are both lines R3+SA, RT
+TD and the same length. Therefore, subarrays 7B and 7C are excited in the same phase as subarrays 78 and 7D. As a result, the radio waves of each subarray 7A, 7B, 7G, and 7D are all combined in the same phase at point P.

In addition, in FIG. 5(b), subarrays 7B and 7
C is rotated 180 degrees with respect to subarray 7A, subarray 7D is in the same attitude as subarray 7A, and in input/output line 9, lines PQ and PR are of equal length, or lines QA and RD are line Both are longer by λg/2 than QB and RC. Therefore, subarrays 7A and 7D are excited with a phase different by π from subarrays 7B and 7C. As a result, each subarray 7A, 7B, 7C17D
The radio waves are all synthesized in the same phase at point P.

<Problems to be Solved by the Invention> Each sub-array is configured to have a phase difference of 90'' between the elliptically polarized waves appearing in batch antenna elements 1 and 4 and the elliptically polarized waves appearing in batch antenna elements 2 and 3. It is configured to generate circularly polarized waves on the output line 5.

However, this condition is only satisfied in the case of a specific center frequency fo, and as the operating frequency moves away from the center frequency fo, circularly polarized waves are no longer synthesized on the input/output line 5, resulting in poor axial ratio characteristics. Become.

In the conventional array shown in FIG. 5, when the operating frequency deviates from the center frequency fo, the elliptically polarized waves generated in the input/output lines 5 of each subarray 7A, 7B, and 7C17D are synthesized in phase as shown in FIG. As a result, an elliptically polarized wave 10 also appears on the input/output line 9. That is, even if the radio waves of each subarray are combined, the axial ratio characteristic will not be improved at all.

In Fig. 5(a), a reflected wave exits from point P, passes through point R, passes through point 3 or point T, is reflected at point A or point 0, and returns to point P, and a reflected wave exits from point P. The reflected wave passes through point Q, passes through point U or 7, is reflected at point B or point 0, and returns to point P. In Fig. 5(b), the reflected wave
The reflected waves that leave the point, reflect at points A and B, and return to point Q are combined in phase, and similarly, the reflected waves that leave point R, reflect at points 0 and 0, and return to point R. Since they are combined in the same phase, the standing wave ratio of the antenna deteriorates.

Therefore, in both of FIGS. 5(a) and 5(b), the frequency band in which good circular polarization characteristics can be obtained is narrow, and the standing wave ratio is also poor.

<Means for Solving the Problems> The present invention further forms an array by further combining four subarrays formed by collectively forming four single-point-fed circularly polarized pouch antenna elements arranged on a planar dielectric substrate. To do this, within each array, four subarrays are arranged at equal angles around the composite point of the array, and the physical posture of each subarray is sequentially rotated by π/2. It is connected to the signal input/output terminal of the array by lines having different line lengths by λg/4 (λt is the wavelength), and the human outputs of each subarray are combined at the signal input/output terminal.

Therefore, since the number of subarrays is four, each subarray is arranged every 90'' around the center of the array, and the physical orientation rotates by 90° in turn.

Then, each subarray is sequentially connected to λg/4 at the signal input/output terminal.
They are connected by lines with different line lengths.

<Function> When receiving radio waves, even if the incoming radio wave of each subarray becomes an elliptically polarized wave due to the center frequency deviating from 0, each subarray sequentially changes its attitude by π/2, and the received radio wave Since the radio waves are synthesized sequentially through lines having different line lengths by λg/4, the radio waves coming from each subarray at the synthesis point have their elliptically polarized waves sequentially different by π/2.

Therefore, as a result of combining these elliptically polarized waves with different orientations, a complete circularly polarized wave is obtained.

Also, since the difference in line length from adjacent subarrays to the synthesis point is λg/now, the reflected waves that leave the synthesis point, are inverted at the input/output points of each subarray, and return to the synthesis point have their phases shifted from each other. Reverse phase by 2π (180' to 0'')
They cancel each other out because they are L/.

As a result, the frequency bandwidth in which circularly polarized wave characteristics can be obtained is greatly expanded, and the standing wave ratio is also improved.

Note that when transmitting using this antenna, the same excellent broadband characteristics can be obtained because the operation is reversible.

Examples In FIG. 1, 7A, 78.7G, and 7D each indicate a subarray. Each subarray is made by connecting four arbitrarily selected single-point-fed circularly polarized batch antenna elements as shown in FIG. 3 in the form shown in FIG. Similar to arrow 8 in the figure, it indicates the physical orientation of each subarray. As is clear from the figure, each subarray is arranged near the four corners of a square, and its physical posture is sequentially rotated by 90 degrees.

The common input/output line 11 connects lines 12 and 13 at point P.
It branches into Line 12 further becomes line 1!8 at point Q.
111 and 15, the line 14 reaches the input point A of the subarray 7B, and the line 15 reaches the input/output point B of the subarray 7B. Further, line 13 further branches into lines 16 and 17 at point R, line 16 reaching input/output point C of sub-array 7C, and line 17 reaching input/output point of sub-array 7D.

Here, when the length PQ of the line 12 is an intersection and the length QA of the line 14 is an intersection 2, the lengths of each line are determined to have the following relationship.

Line 12 PQ=cross.

Track 14 QA=See 2 Track 16 RC=See.

Therefore, the line lengths from point P to the input/output points of each subarray differ by λg/4 in turn.

As described in L, each subarray has a different attitude by 90 degrees, and the line length from the common input/output point P is input in order.
As a result, as shown in FIG. 2, as shown in FIG. 2, at point P, the circularly polarized waves 18 are synthesized by combining the elliptical polarizations that differ by 90'' from each other.

Also, the reflected waves that go out from point Q, reflect at points A and 8, and return to point Q cancel each other because their phases differ by 180 degrees, and similarly go out from point R and reflect at points 0 and 0. The reflected waves that returned to point R also cancel each other because they differ by one phase or 180@. Therefore, it is possible to maintain a good standing wave ratio.

FIG. 7 shows the axial ratio-frequency characteristics of the above embodiment (solid line) and the conventional example (dotted line) shown in FIG.
Comparing the B level, the conventional example can only obtain a bandwidth of less than ±1%, whereas the above embodiment can actually obtain a bandwidth of ±3% or more.

FIG. 8 shows the cross-polarization protection ratio-frequency characteristics of the above embodiment (solid line) and the conventional example (dotted line) shown in FIG. 9
While only 8% of the bandwidth can be obtained, in the above embodiment, a bandwidth of 6.55% can be obtained.

<Effects of the Invention> As is clear from the above embodiments, according to the present invention, the bandwidth in which the microstrip batch antenna operates with circularly polarized waves is greatly expanded, and the standing wave ratio on the line is greatly increased. It can be improved.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an array embodying the present invention, Fig. 2 is an explanatory diagram of the operation of the array, Fig. 3 is a plan view of various conventional batch antenna elements, and Fig. 4 is an example of a conventional sub-array. A plan view, FIG. 5 is a configuration diagram of a conventional array, FIG. 6 is an explanatory diagram of the operation of the array shown in FIG. 5, FIG. 7 is an axial ratio-frequency characteristic diagram of the above embodiment and the conventional example, and FIG. is a cross-polarization protection ratio-frequency characteristic diagram of the above embodiment and the conventional example. 7A to 7D... Sub-arrays 12 to 17... Lines, signal input/output terminals of the array.

Claims (1)

[Claims] (1) In a circularly polarized planar antenna in which a fixed number of batch antenna elements arranged on a planar dielectric substrate are grouped together to form a subarray, and these subarrays are further grouped into four subarrays to form an array. The sub-arrays are arranged at 90° intervals around the composite point of the array, and their physical postures are sequentially rotated by π/2,
Furthermore, the planar antenna is characterized in that these sub-arrays are respectively connected to the signal input/output ends of the array by lines having different line lengths by λg/4 (λg is the line wavelength).