JPS63167502A - Circularly polarized wave micro strip type antenna equipment - Google Patents

Abstract

PURPOSE:To obtain an antenna equipment of high arrangement efficiency by using a ring type hybrid circuit as the hybrid circuit which supplies a high-frequency current to a circularly polarized wave micro strip type antenna equipment. CONSTITUTION:A high-frequency signal outputted from a transmitter 10 is equally divided into four by a power divider PD and is sent to hybrid circuits 20-23 as feeding circuits of circularly polarized wave micro strip type antennas (MSA) 7-10. Circuits 20-23 are arranged on about axes of MSAs on the rear face of a substrate 18. Since circuits 22-23 are formed as ring type, MSAs 7-10 are arranged in order while successively being rotated at 45 deg., and distances between output terminal of circuits 20-23 and feeding points 3 and 4 of MSAs are equalized and they are connected with straight lines.

Description

[Detailed Description of the Invention] This invention provides a circularly polarized microstrip antenna device,
The present invention relates to a circularly polarized microstrip antenna device that is installed on a mobile station during communication between a mobile station such as an aircraft and a ground station via an artificial satellite, for example.

[Prior art]

The polarization methods of electromagnetic waves (hereinafter referred to as radio waves) can be roughly divided into linear polarization and circular polarization, but in various communications via artificial satellites, low attenuation in obstacles such as raindrops is required. The circular polarization method has been adopted due to its advantages such as not requiring polarization tracking, and in recent years attempts have been made to conduct public communications between aircraft and ground stations via this artificial satellite. The radio waves used in this case require two frequencies for transmission and reception because it is necessary to connect to a telephone line that transmits and receives at the same time, and in order to avoid mutual interference between transmitters and receivers, the two frequencies are separated for a certain period of time. There must be. Therefore, the antenna used for this requires an antenna that can adapt to the image frequencies for transmission and reception.

On the other hand, it is desirable for aircraft antennas to be small and light, and furthermore, to be as thin as possible, and due to this requirement, a circularly polarized microstrip antenna device (hereinafter referred to as MSA) is considered to be a promising antenna for use in this purpose. ing. The MSA includes a microstrip antenna MSAI having a radiation pattern such as a disc-shaped radiator 1 with a notch 2 formed in a part of its circumference, as shown in FIG. This MSA
Although it has circular polarization characteristics, it has a single-point feed, and has the excellent advantage of not requiring a hybrid circuit as a feed circuit, but it has an extremely narrow band, so it cannot be used as an antenna for both transmission and reception. Can not.

FIG. 10 and FIG. 11 show a perspective view and a sectional view of an example of the MSA 2 of the two-point power feeding system. This integrates the radiator pattern 5 and the branch line type hybrid circuit 9 facing each other on the surfaces of the dielectric substrates 6 and 8 with the ground plate 7 in between, and also connects the feed points 3 and 4 of the radiator pattern 5 to each other. and the output end of the hybrid circuit 9 are arranged at the same position, and the two are connected by a pin passing through the dielectric substrate 6.8 and the ground plate 7. At this time, the line impedance of the hybrid circuit 9 is set such that the high frequency currents supplied to each feed point 3.4 of the radiator pattern 5 have a phase difference of 90'' from each other, and the impedance of the feed point is matched with a signal source (not shown). By determining the value of and the length of the line in each section, this MSA2 emits circularly polarized radio waves,
It can also be received. The branch line type hybrid circuit 9 used at this time is generally a microstrip line having the shape shown in FIG. 2 like this
Although the point feeding system MSA2 has a wider frequency characteristic than the single point feeding MSAI, it is still insufficient for practical use, and cannot be used as is as an antenna for public communication on the aircraft, etc. Therefore,
Conventionally, as a means to make this antenna have wideband characteristics, it has been proposed, for example, in Japanese Patent Laid-Open No. 59-178002, to arrange two-point feeding system MSA2 on the same plane under predetermined conditions to form a sequential array. Conceivable. However, in this case, the above-mentioned branch line type hybrid circuit is required for each of the radiator patterns arranged as detailed below, and when a large number of antennas are arranged in an array, the area of the entire antenna increases, making it unsuitable for mounting on an aircraft. There is.

In order to facilitate understanding of the present invention, the principle of the sequential array SA proposed in the above-mentioned Japanese Patent Application Laid-Open No. 178002/1982 and the drawbacks when using a branch line type hybrid circuit will be explained below using drawings. do. It goes without saying that the characteristic in this case is that an array of antennas has a wider band than a single antenna.

Figure 13 shows four microstrip antennas MSA3.
It is a configuration diagram of an MSA array antenna when MSAs 6 are arranged in one row, as seen from the feeder circuit side. In the same figure, 10
is a transmitter, and the high frequency current output from it is divided into four equal parts by a power divider PD, and then the output is connected to one input terminal of the branch type hybrid circuits 11 to 14 attached to each radiator pattern. be done. At this time, the other input end of the hybrid circuit is connected at the line impedance value. The hybrid circuits 11 to 14 ultimately divide the supplied high-frequency current into two halves and output the two pairs of output terminals with the phases shifted by 90 degrees, which are then supplied to the power feeding point 3.4 of the MSA. Ru. In this case, as shown in FIG. 13, one of the conditions for forming an array is to set the power feeding positions to the four MSAs at points rotated by 45 degrees around the center of the circle.

M of sequential array SA configured as above
By supplying a high frequency current whose phase is shifted by π/4 (rad) in the order from SA3 to MSA6, an antenna with a good axial ratio can be provided. Regarding the voltage standing wave ratio (VSWR), the phase of the reflected wave from each MSA is shifted by twice that of each supply line (round trip) when viewed from the input end of the power divider PD, so the reflection coefficient of each MSA is If all are equal, then M
If SA3 is used as a reference, =1-j-1+j=0, and the total sum of reflected waves becomes zero. That is, the reflected energy from each MSA is canceled within the pub-divider PD and does not appear at the transmitter. Therefore, the VSWR seen from the transmitter is 1, and ideal characteristics can be obtained.

[Problem that the invention seeks to solve]

However, in order to configure the above-mentioned high-performance sequential array SA, the high-frequency current supplied to the two feed points 3 and 4 of each MSA must maintain a phase difference of 90'' from MSA3 to MSA
6, the phases of the high-frequency currents are shifted by π/4 from each other,
And the total sum of the reflected waves of each MSA is the power divider - PD
This becomes possible only if it becomes zero when viewed from the input end of .

In order to satisfy this condition, it is necessary to strictly set the length of the transmission path from the power divider PD to the feeding point of each MSA. That is, the hybrid circuit work 1 shown in FIG.
Even if a 90° phase difference is maintained at the output end of the MSA 3, if the lengths of the lines 15 and 16 from there to the feed point 3°4 of MSA3 are equal, a 90' phase difference will occur at the feed points 3 and 4. cannot be maintained. In addition, the high frequency current supplied to each MSA3 etc. is π/4 (
rad) As mentioned above, it is necessary to shift the phase, but this depends on the length of the lines L1 to L4 from the power divider PD to each hybrid circuit and the lengths of lines i5 to 112 from each hybrid circuit to each MSA. This is done by adjusting the line length, but for this purpose, the length of each line during this period must be set precisely. By doing so, the effect of reducing the total sum of reflected waves at the input end of the power divider PD to zero can be obtained as described above. 13th
The output end and feed point 3 of the hybrid circuit 11 etc. shown in the figure.
The wiring lines 15 to f12 that connect 4 are bent at right angles at various places, but this is because when L1 to L4 have the same line length, a sequential array SA is constructed in a limited space. This is not a desirable measure in terms of the transmission characteristics of each hybrid circuit, and there is considerable concern that the antenna characteristics may deteriorate due to this. That is,
In order to prevent characteristic deterioration, it is desirable that the shape of the input/output line of each branch-line type hybrid circuit be a straight line as shown in FIG. In addition, each branch line type hybrid circuit itself also needs to be sequentially rotated, and it is easy to understand that if this is done, the required area of the power supply circuit will be significantly increased. Normally, the interval between MSA is MS
It is determined from the viewpoint of mutual connections between A and cannot be arbitrarily selected. Therefore, it is difficult to actually widen the distance between MSA.

[Purpose of the invention]

The present invention was made in order to solve the problems of the conventional sequential array SA as explained above, and it is easy to determine the line from the power divider to the feeding point of each radiator pattern, and it is extremely It is an object of the present invention to provide a circularly polarized microstrip type antenna device that can reduce the required area by efficiently arranging a feeding circuit pattern.

[Means for solving problems]

In order to achieve the above object, the present invention employs a ring-type hybrid circuit that can be used freely as a hybrid circuit that supplies high-frequency current to the MSA.

[Effect]

By adopting the above-mentioned means, the present invention has a wide degree of freedom in designing, and can easily achieve high performance, a wide band, extremely efficient arrangement of each feeder circuit, and a small overall area required for a circularly polarized microstrip type antenna device. It becomes possible to manufacture

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, this invention will be described in detail based on illustrated embodiments.

FIG. 1 is a configuration diagram of a sequential array SAI constructed by arranging four microstrip antennas MSA7 to MSAIO in a line according to the present invention, as viewed from the power supply circuit side. In the figure, 10 is a transmitter, and the high frequency signal outputted from it is transmitted through a power divider - PD.
As in the conventional case, the power is divided into equal parts and sent to hybrid circuits 20 to 23, which are the power supply circuits of each MSA. The hybrid circuit used in this sequential array SAI has a ring shape as shown in Figure 2, and by using this, extremely effective power supply circuit pattern arrangement is possible as explained in detail below. .

The input impedance of each MSA is 1 at the frequency factor ◎
00Ω, and the input and output of each hybrid circuit.
The characteristic impedance of the output line is 100Ω. The configuration of the branch line type hybrid circuit 9 and ring type hybrid circuit 19 having the above characteristics is that the characteristic impedance of R1-R6 is 100Ω, the characteristic impedance of R7 and R8 is 70.7λ g · (7ρ, 7) Ω, and 11 The length of is □.

λg' (The length of 1e x 12 is □. Here, λg-(7o, t) indicates the substrate wavelength of the 70.7Ω line, and λg·(166) indicates the substrate wavelength of the 100Ω line.

Therefore, the circumference of the ring hybrid circuit 19 is L=
(λg・(qo, q) / 4+λg−C+oo)
/4) X 2, and the radius a is L/2π.

The conventional branch line type hybrid circuit 9 is the 12th
It is generally used in the state shown in the figure, R1, R
2, R4, and R5 to fit within the framework of the hybrid circuit 9 is not common, but it is not impossible, and is considered within the scope of the present invention.

However, the ring-type hybrid circuit 19 shown in FIG.
This is probably more advantageous because there is no deterioration in transmission characteristics, phase difference characteristics, and other initial characteristics even when used in the conditions shown in Figure 3 (al~(0)).The ring type hybrid shown in Figure 2 Figures 4 to 7 show the characteristics of the circuit 19 manufactured using a microstrip line and measured.The thickness of the substrate at this time was 0.7 mm, the relative dielectric constant E, = 2.5, and the dielectric loss tan (F = 1.8 x 10-' Teflon material is used, and the thickness of the copper thin layer is 0.035 mm. Figure 4 shows the reflection characteristics, Figure 5 shows the phase difference characteristics between the output terminals, and Figure 6 shows the power. , and FIG. 7 shows the isolation characteristic.From these characteristics, even if the ring-type hybrid circuit 19 shown in FIG. 2 is used as shown in FIG. It is clear that there is no deterioration.

FIG. 1 shows a case in which a sequential array is constructed using a ring-type hybrid circuit 19 having the above characteristics. FIG. 1 is a configuration diagram of a sequential array SAI in which four MSAs are arranged in a line, as seen from the power supply circuit side.
The MSA is located on the back of the MSA approximately at the central axis of each MSA. It is clear from FIG. 13 that the hybrid circuit can be placed in the position described above only by making it into a ring type, which is impossible with the conventional branch line type hybrid circuit 9. be. This makes it possible to reduce the area occupied by each MSA including the hybrid circuit, and it becomes possible to downsize the sequential array SA1 constituted by a plurality of MSAs.

More importantly, the hybrid circuit has a ring shape, so it can be arranged in a 45° rotation from MSA7 to MSAIO, and the output end of the hybrid circuit 20 etc. and the feeding points 3 and 4 of each MSA can be arranged in a 45° rotation. This makes it possible to make the distances between all the lines equal and to connect them in a straight line. If the distances between the output end of the hybrid circuit and the feed points 3 and 4 of each MSA are made equal, the absolute value of the reflected waves of each MSA will be the same and only the phase will differ. The total sum of reflected waves is zero, and ideal characteristics with a voltage standing wave of 1 can be obtained. Since the output end of the hybrid circuit 20 etc. and the feed point 3.4 of each MSA can be connected in a straight line, there is no deterioration of the transmission characteristics (
, Therefore, a high-performance antenna can be constructed.

To configure a sequential array with the four MSAs shown in Fig. 1, from MSA7 to MSAIO, π/4
(rad) As described above, the phase-shifted high-frequency current is supplied, and as a means to shift the phase, the lines L5 to 1 from the power divider PD to each hybrid circuit are
This can be done by changing either the length of L8 or the length of R1.

The power divider PD of the sequential array SAI shown in FIG. 1 may be mounted on the substrate 18 and integrated, or may be separate. The lines L5 to L8 connecting the power divider PD and the hybrid circuit 20, etc., may all be configured with microstrip lines, or may be connected halfway with coaxial cables.

Although the sequential array SAI in FIG. 1 is configured with four MSAs for ease of explanation, it is not limited to this number. FIG. 8 shows the measured values of the reflection characteristics seen from the input side of the power divider PD when 16 MSAs are arranged in 2 rows and 8 columns to form a sequential array. Looking at this, it can be seen that the characteristics of the MSA alone have been improved over the entire band.

Note that the present invention can be used not only for the above-described MSA but also for a feeding circuit for a normal array antenna.

〔Effect of the invention〕

By adopting the configuration described above, the present invention can provide a circularly polarized microstrip type antenna device that is small in size, has low transmission loss in a feeding circuit, and has a voltage standing wave ratio close to an ideal value.

[Brief explanation of the drawing]

1 to 8 show embodiments of the present invention, in which FIG. 1 is a configuration diagram seen from the power supply circuit side of a sequential array, FIG. 2 is a diagram showing a ring type hybrid circuit, Figure 3 (a), (b), (cl, (d), (e),
(f), (g), (h), (i). (J), (kl, (11, (ml, (n), (
o) is a diagram showing a modification of Figure 2, Figure 4 is a diagram showing the reflection characteristics of the hybrid circuit in Figure 2, and Figure 5 is a diagram showing the phase difference characteristics between the output terminals of the hybrid circuit in Figure 2. Figure 6 is a diagram showing the power distribution characteristics of the hybrid circuit in Figure 2, Figure 7 is a diagram showing the isolation characteristics of the hybrid circuit in Figure 2, Figure 8 is a diagram showing the microstrip antenna. FIG. 2 is a diagram showing the reflection characteristics when configured into a sequential array of 2 rows and 8 columns. 9 to 13 show conventional examples, in which FIG. 9 is a top view of a microstrip antenna with a notch provided on the circumference, FIG. 10 is a perspective view of the microstrip antenna, FIG. 11 is a sectional view of FIG. 10, FIG. 12 is a block diagram of a branch line type hybrid circuit, and FIG. 13 is a schematic diagram of a sequential array using a branch line type hybrid circuit. 3.4・・・・・・−1−−−・Feeding point 5−−−−
-----Radiator pattern 6.8--------1---Dielectric substrate 7------ Earth plate 9.11, 12. 13.14 ...------m---・Branch line type hybrid circuit 19.20.21, 22.23 11---------Ring type hybrid circuit MSA・−・−−−−−1−−−−・Microstrip antenna agent Patent attorney Katsuya Takayama Figure 3 (a) (b) Busy (m)
(n) (o) Figure 9 Figure 11

Claims (4)

[Claims] (1) A circularly polarized microstrip antenna device characterized in that a ring-shaped hybrid circuit with flexible input and output wiring directions is used in the feeding circuit. (2) The ring-shaped hybrid circuit pattern is installed as a power supply circuit on the back surface of a substrate on which an electromagnetic wave radiator pattern is formed, with the center of the ring-shaped hybrid circuit pattern coinciding with substantially the central axis of the radiator pattern. A circularly polarized microstrip antenna device as described in Scope 1. (3) Claim 1, wherein the feeding point of the radiator pattern and the output end of the ring-type hybrid circuit pattern are located at the same position on the front and back surfaces and are connected by an electric path passing through the substrate on the front and back sides. Or a circularly polarized microstrip antenna device according to claim 2. (4) A sequential array antenna was constructed by arranging a plurality of the circularly polarized microstrip antenna devices on the same substrate, sequentially rotating the feed point position of each antenna by a predetermined angle, and shifting the phase of each input/output signal. A circularly polarized microstrip antenna device according to claims 1 to 3.