JPH04234206A - Compound plane antenna - Google Patents

Abstract

PURPOSE:To obtain a compound plane antenna displaying broad band characteristics in plural available frequency bands, respectively. CONSTITUTION:Plural parasitic conductors 13, 15 with almost the same shape as that of plural plane radiant conductors 33, 41 excited by different frequencies, respectively are arranged at the front of the radiant conductors.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite planar antenna that exhibits broadband characteristics in a plurality of frequency bands. [0002] Hitherto, a wireless communication system is known that is constructed between a base station on the ground and a mobile station using a geostationary artificial satellite as a relay. In such a wireless communication system, downlinks are configured from a base station to a large number of mobile stations via satellites, and uplinks are configured from each mobile station to the base station. The frequency used in the uplink is, for example, 1.6 GHz, and the frequency used in the downlink is, for example, 2.5 GHz. The antenna on the mobile station side needs to have a simple configuration, a small shape, and a low profile like a microstrip antenna. [0003] As a low profile antenna as described above, the present applicant has proposed
In No. 686, a circular antenna is combined with a microstrip antenna having a circular radiating element (hereinafter referred to as a disk antenna), and the diameter of the circular radiating element is set smaller than the inner diameter of the circular radiating element of the circular antenna. , by placing the circular radiating element concentrically with the annular radiating element,
A composite antenna has already been proposed that has a small and simple configuration and allows the polarization characteristics and radiation characteristics of each unit antenna to be arbitrarily set even in a plurality of relatively close frequency bands. First, a previously proposed composite antenna will be explained with reference to FIGS. 7 and 8. 7 and 8, 30 is a circular antenna, in which a circular conductor (radiating element) 33 is placed on a circular ground conductor 31 via a low-loss dielectric layer 32 such as fluororesin. are coaxially stacked, and the inner circumferential portion 33i of the annular conductor 33 is connected to the ground conductor 31 via through holes 34 at many locations. The circular conductor 33 is provided with two feeding points 35 and 36 equally offset from its center, and coaxial feeding lines 37 and 38 are connected to both feeding points 35 and 36, respectively. In this case, the outer conductors of both feeder lines 37 and 38 are connected to the ground conductor 31. A circular conductor (radiating element) 41 is arranged concentrically inside the circular conductor 33 on the dielectric layer 32 of the circular antenna 30, forming a circular plate antenna that shares the ground conductor 31. Ru. This disc conductor 41 is also provided with feeding points 42 and 43 at two locations equally offset from its center, and both feeding points 42 and 43 are provided independently of the circular antenna 30.
Coaxial feed lines 44 and 45 are connected to 3, respectively. As will be described later, the radiating element 41 is excited in the TM21 mode, but in modes other than the TM01 mode, as is well known, the impedance at the midpoint of the radiating element 41 is basically 0Ω, so the through hole 46 The central portion of the disc conductor 41 is connected to the ground conductor 31 via the ground conductor 31 to stabilize the operation. Note that the disc conductor 41 and the circular conductor 33 are
It can be easily formed by etching the same copper-clad laminate. Further, it is not necessary to align the feeding points of each radiating element 33, 41 in the radial direction. [0008] The previously proposed composite antenna is, for example, 1.6G
When used in the Hz band and 2.5 GHz band, respectively,
The radius of the radiation conductors 33 and 41 and the radius, thickness, and dielectric constant of the dielectric layer 32 are set, for example, as follows. ro33=71.0mm,
ri33=42.0mm, r41=3
5.5mm r32 = 100mm,
t32 =1.6mm, ε
r = 2.6 [0009] Also, each feeding point 35, 3
6; The offset distance and angular interval of 42 and 43 are set as follows, for example. rf3 =53.0mm,
rf4 = 17.0mm, θ = 135
The operation of the previously proposed example described above is as follows. For example, in the 1.6 GHz band and the 2.5 GHz band, the radiating element 33 of the circular antenna and the radiating element 41 of the circular antenna are both excited in the TM21 mode with a phase difference of 90°, The radiating element 41 emits right-handed circularly polarized waves, and the radiating element 33 emits left-handed circularly polarized waves. Then, the desired vertical directivity, each approximately conical, is obtained. [0011] In this proposed example, by combining a circular antenna and a circular plate antenna, even though they share a ground conductor, the isolation between the two is large and the feeding system is independent. Therefore, each resonance frequency, polarization characteristic, and radiation characteristic can be set arbitrarily. However, in the previously proposed composite antenna as described above, each of the annular antenna and the disc antenna is
For example, it exhibits impedance characteristics as shown in Figures 9 and 11, and voltage standing wave ratio (VSW) as shown in Figures 10 and 12.
Since the frequency bands in which R) is within 2 are extremely narrow, for example less than 1% each, especially when two frequencies are shared,
There was a problem in that dimensional accuracy had to be strictly controlled during manufacturing, which increased costs. However, in the field of microstrip antennas, parasitic elements of the same shape are loaded in front of the radiating element of a circular plate antenna, and each element is excited at a different frequency.
There are some that have a wide band or share two frequencies. However, conventional parasitic element-loaded microstrip antennas have only been able to satisfy either dual frequency sharing or broadbandization, and none have been able to achieve both at the same time. [0014] In view of the above, an object of the present invention is to provide a composite planar antenna that exhibits broadband characteristics in each of a plurality of usable frequency bands. [Means for Solving the Problems] The present invention provides a dielectric layer 3
This is a composite planar antenna that supplies power of different frequencies to a plurality of flat radiation conductors 33 and 41 facing a ground conductor 31 through a ground conductor 31, wherein the plurality of radiation conductors are arranged in front of the plurality of radiation conductors. This is a composite planar antenna in which a plurality of parasitic conductors 13 and 15 each having approximately the same shape are arranged. [0016]According to the present invention, it is possible to obtain a composite planar antenna that exhibits broadband characteristics in each of a plurality of usable frequency bands. [Embodiment] An embodiment of the composite planar antenna according to the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, parts corresponding to those in FIG. 8 described above are given the same reference numerals, and redundant explanation will be omitted. In Figure 1, 10
is a loaded element group, in which a parasitic circular conductor 13 and a disc conductor 15 are arranged concentrically on one surface of a low-loss dielectric layer 12 such as fluororesin. Through holes 14 and 16 are formed at the periphery and at the center of the disc conductor 15, respectively.
is drilled. Although not shown, the annular conductor 13 and the disc conductor 15 of the loading element group 10 are coaxially arranged facing the radiating elements 33 and 41 by an appropriate coupling member and a spacer of a predetermined thickness, so that they correspond to each other. Through holes 14, 34 and 1
6 and 46 are connected by conductive wires 17, respectively. The rest of the configuration is the same as in FIGS. 7 and 8 described above. When the composite planar antenna of the above embodiment is used, for example, in the 1.6 GHz band and the 2.5 GHz band, the loading conductors 13 and 15 and the radiating conductors 33 and 41
The radius, the radius, thickness and dielectric constant of the dielectric layers 12 and 32, and the distance between both dielectric layers are set, for example, as follows. ro13=76.5mm,
ri13=42.0mm, r15=3
8.5mm ro33=71.0mm,
ri33=42.0mm, r
41 = 35.5mm r12 = r32
=100mm, t12 =t32 =1.6mm,
εr=2.6,
d1 = 10mm [0020] Also, each feeding point 35
, 36; 42, 43 are set, for example, as follows. rf3=59.0mm,
rf4 =22.0mm, θ=135°
Comparing these values with the values of the previously proposed example described above, it is found that the outer diameters of the loaded conductors 13 and 15 are slightly larger than the outer diameters of the corresponding radiating conductors 33 and 41, and that each feeding point It can be seen that the offset distance of the example is slightly larger than that of the previously proposed example. In the composite planar antenna of the above embodiment,
Each of the circular antenna and the disc antenna exhibits impedance characteristics as shown in FIGS. 2 and 4 for each frequency used, and as shown in FIGS. 3 and 5, the frequency band where the VSWR is within 2 is For example, the bandwidth is 3.35% and 2.53%, respectively, which is much wider than the previously proposed example, so it is possible to ignore deviations in the resonant frequency due to processing accuracy or changes in the usage environment. This is particularly suitable when two frequencies are shared. Next, another embodiment of the composite planar antenna according to the present invention will be described with reference to FIG. The configuration of another embodiment of the invention is shown in FIG. In FIG. 6, parts corresponding to those in FIGS. 1 and 8 are given the same reference numerals and redundant explanation will be omitted. In Figure 6, 10s
is a loaded element group, in which a parasitic circular conductor 13 and a disc conductor 15 are arranged concentrically on one surface of a low-loss dielectric layer 12s such as fluororesin. Around the periphery
A plurality of relatively large diameter through holes 14b are provided at predetermined angular intervals, and a relatively large diameter through hole 16b is also provided at the center of the disc conductor 15. In this embodiment, the loading element group 10s is coaxially arranged with the annular conductor 13 and the disk conductor 15 facing the radiating elements 33 and 41, respectively. The radiating elements 33 and 41 each have a low-loss dielectric layer 32 such as a fluororesin on a circular ground conductor 31s.
They are coaxially stacked and arranged via s. Further, in this embodiment, the radius of the ground conductor 31s and the dielectric layer 32s is made slightly larger than the outer diameter of the radiating element 33. A large-diameter conductive plate 2 made of aluminum material, for example, is placed in contact with the ground conductor 31s.
1 is provided. This conductive plate 21 has approximately the same diameter as the grounding conductor 31 of the previously proposed example shown in FIGS. will be established. Furthermore, a plurality of relatively large diameter through holes 34b are provided at predetermined angular intervals on the inner peripheral portion 33i of the circular conductor 33, and a relatively large diameter through hole 34b is also provided at the center of the circular conductor 41. A through hole 46b is provided. Radiation conductor 33
, 41 through holes 34b, 46b and loading conductor 13
, 15 are commonly inserted through the corresponding through holes 14b, 16b, and the screws 23 are engaged with the screw holes 22 of the conductive plate 21, so that the loading conductors 13, 15 and the radiation conductors 33, 41 are inserted into the corresponding through holes 14b, 15, respectively. It is coupled to a conductive plate 21. The rest of the configuration is the same as in FIGS. 1 and 8 described above. When the composite planar antenna of the embodiment shown in FIG. 6 is used, for example, in the 1.6 GHz band and the 2.5 GHz band, the radius of the loaded conductors 13 and 15, the conductive plate 21, and each radiation conductor 33 and 41 , the thickness and dielectric constant of the dielectric layers 12 and 32s, and the distance between both dielectric layers are set, for example, as follows. ro13=76.5mm,
ri13=42.0mm, r15=3
8.5mm ro33=71.0mm,
ri33=42.0mm, r
41 = 35.5mm r12 = r32
=77mm, t12 =t32 =1.6mm,
εr=2.6,
d2 =8.5mm, r21 =1
With the above-described configuration, the embodiment shown in FIG. 6 can also achieve the broadband characteristics shown in FIGS. Layers can be saved, and desired frequency characteristics can be achieved stably and economically. Effects of the Invention As detailed above, according to the present invention,
In front of a plurality of flat radiating conductors that are excited at different frequencies, a plurality of parasitic conductors having almost the same shape as the radiating conductors are arranged, so each of them can be used in a wide range of frequency bands. A composite planar antenna exhibiting characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an embodiment of a composite planar antenna according to the present invention;

[Fig. 2] A Smith chart showing the characteristics of the main parts of an embodiment of the present invention.

[Fig. 3] Diagram showing characteristics of main parts of an embodiment of the present invention,

FIG. 4 is a Smith chart showing the characteristics of other essential parts of an embodiment of the present invention;

FIG. 5 is a diagram showing the characteristics of other main parts of an embodiment of the present invention;

FIG. 6 is a sectional view showing the configuration of another embodiment of the present invention;

[Fig. 7] A plan view showing an example of the configuration of a composite antenna according to an existing proposal.

[Figure 8] Cross-sectional view showing the configuration of an existing proposed example,

[Figure 9
] Smith chart showing the characteristics of the main parts of the already proposed example,

[Figure 10] Diagram showing the characteristics of the main parts of the existing proposed example,

[Figure 11] Smith chart showing the characteristics of other important parts of the already proposed example,

FIG. 12 is a diagram showing the characteristics of other main parts of the already proposed example.

[Explanation of symbols]

12, 32, 12s, 32s dielectric layer 13, 15
Parasitic element (loaded conductor)

Claims (1)

[Claims] 1. A composite planar antenna that supplies power of different frequencies to a plurality of flat radiation conductors facing a ground conductor via a dielectric layer, the antenna comprising: A composite planar antenna characterized by disposing a plurality of radiating conductors and a plurality of parasitic conductors having substantially the same shape.