JPH03227103A - Microstrip array antenna - Google Patents

Abstract

PURPOSE:To realize a microstrip array antenna without any spurious radiation, with simple structure of a feeding circuit and enough space margin by connecting a radiation element to a radiation element excited through a coupling opening such as a slot. CONSTITUTION:An antenna board 5, a metallic foil 6 and a feeder board 8 are laminated so as to be in close contact with each other and a slot 3 excited by a slot exciting feeder 7 excites further a radiating element 1. Thus, an electromagnetic wave of a linearly polarized wave having a y-direction electric field component radiates from the element 1 by selecting the size of the slot 3 and the element 1 so that the resonance is caused at the desired frequency. Moreover, a radiation element feeder 2 is connected with the edge of the element 1 in the polarized wave direction, and further a linearly polarized wave radiation element 4 with the same polarized wave and same resonance frequency is also connected. Through the constitution above, other radiation element connected to a microstrip array antenna is excited by directly exciting one radiation element of the microstrip array antenna.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a planar antenna used as a microwave band antenna, and in particular to an electromagnetic coupling type microstrip in which a feed line board and a radiating element board can be separated. This relates to array antennas.

(Summary of the Invention) This invention relates to a microstrip array antenna used as a transmitting and receiving antenna in the microwave band. Coupling between antennas of mutually adjacent units is achieved through a feeding line for a radiating element, a single coupling opening located at an edge of the radiating element, and a feeding line for excitation of the coupling opening. has been done.

In this way, the configuration of the feed line connecting the radiating elements is simplified, the length of the feed line is shortened, unnecessary radiation is reduced, and deterioration of the radiation directivity characteristics of the antenna and decrease in antenna efficiency are also suppressed.

(Prior Art) Many microstrip antennas have been reported so far, in which a feed line board and a radiating element board are separated and the radiating element is excited by electromagnetic coupling. In particular, for excitation of a radiating element by a feed line for slot excitation created on a feed line board via a slot, for example, Document ID, M, Pozar & D, H, 5c.
haubert: llComparisonof
Architectures for Monoli
thic Phased Array Antennas
”, MICROWAVE JOIJRNAL, p.
p, 93-1093-1O41986.

For example, arrays created using this method include:
Literature 2. J, F, ZIJRCHER: ”The
5SFIP:A Global Concept
for old gh-performance Broadb
and Planar Antennas, EL
ECTRONIC5LETTER510th, Nov
ember 1988, Vol, 24. No, 2
There are 3.

On the other hand, there is a type that connects a large number of radiating elements with feed lines on the same board to form an array antenna, and then excites a part of the feed line with a slot, for example, as described in Reference 3. Masayuki Nishiyama,
Yoshihiko Ito: “Broadband expansion of waveguide-fed planar array element antennas,” Institute of Electronics, Information and Communication Engineers, Microwave Research Group Materials, MW 87-33゜pp, 23-28.1987
Alternatively, an example in which one of the radiating elements is removed and a coupling probe is provided in that part as a feeding point, for example, see Document 4. JP-A-62220003' has a planar array antenna.

(Problem B to be solved by the invention) In 20 examples of literature in which array antennas are configured by electromagnetic coupling through slots, all the radiating elements are directly fed power through the slots, and the feed line is connected to the bottom of each radiating element. Wired to excite the slot. As a result, the power supply line becomes complicated, and there is no space available for incorporating and activating an amplifier or a phase shifter. On the other hand, in the method of Reference 31 and Reference 4, the blocked microstrip array is excited by a single slot or probe, so the feeder line for exciting the slot is not complicated, and the space required to incorporate the active element is reduced. I can also afford it.

Therefore, it can be said that this is the optimal configuration method for active microstrip array antennas. However, the method of Reference 3
Since the radiating element is coupled to the strip line on the substrate through the slot, direct radiation from the slot into space is unavoidable, and not all of the power excited in the slot is transmitted to the radiating element. Therefore, the efficiency of the antenna decreases. Further, the method of Document 4 has the problems of Document 3 as well as requires space for the probe on the radiating element substrate. Furthermore, the end of the feed line connected to the removed radiating element must be terminated with a resistor having the same characteristic impedance as the feed line, which makes manufacturing complicated.

Therefore, an object of the present invention is to provide a microstrip antenna in which a radiating element board and a feeder board are separated and the excitation of the radiating element is performed by electromagnetic field coupling via a slot, which eliminates unnecessary radiation from the coupling part, and which It is an object of the present invention to provide a microstrip array antenna suitable for an active antenna, which has a simple feeding circuit for exciting an aperture and has ample space.

(Means for Solving the Problems) In order to achieve this object, the microstrip array antenna according to the present invention includes a radiating element substrate on which a plurality of radiating elements are arranged in an array, and a radiating element substrate on which a plurality of radiating elements are arranged in an array. In an electromagnetically coupled microstrip array antenna comprising a feed line substrate having a coupling opening and an excitation feed line, and a metal foil inserted between the substrates and having a coupling opening, two antennas are arranged adjacent to each other. Coupling between unit antennas each including one radiating element is a coupling between a feeding line for the radiating element on the radiating element substrate connected to the radiating element and a coupling provided on the metal foil to excite only one radiating element. The present invention is characterized in that it is configured to be achieved through the opening for coupling and the feeder line for excitation through the coupling opening on the feeder line board.

(Function) According to the present invention, when configuring an electromagnetic field coupling type microstriab array antenna, there is no need to excite part of the feed line in the microstrip array antenna by electromagnetic coupling, etc. By exciting one radiating element of a strip array antenna, other radiating elements connected to it can also be excited. Therefore, the configuration of the feeder line connecting the radiating elements is simplified, and the length of the feeder line is also shortened. Furthermore, since the radiating element is directly excited, there is no unnecessary radiation from the coupling part, which occurs when part of the feeder line is excited, and there is no deterioration of the radiation directivity characteristics of the antenna or decrease in antenna efficiency.

(Examples) The present invention will be described in detail below by way of examples with reference to the accompanying drawings.

An embodiment in which the present invention is applied to a linearly polarized microstrip antenna will be described with reference to FIG.

The configuration of the first illustrated embodiment includes a radiating element 1, a radiating element feed line 2, a slot 3, and a linearly polarized radiating element (another radiating element) 4.

A radiating element feed line 2 is connected to the element edge portion in the excitation direction of the radiating element 1 excited by the slot 3, and further,
Linearly polarized wave radiating elements 4 having the same polarization and the same resonance frequency are connected. This constitutes the basic connection of the series-parallel feeding type array unit antenna. In order to equalize the phase of each radiating element at the resonant frequency, the length of the radiating element feed line 2 is λg/2 (λg = c / (f -7iTT
), where C is the speed of light and f is the resonant frequency of the radiating element.

The configuration of the first embodiment will be described in more detail with reference to FIG. 2 (partial configuration diagram) and FIG. 3 (diagram showing the positional relationship of each part). In FIG. 2, an antenna board (radiating element board) 5, a metal foil 6, and a feed line board 8 are laminated so as to be in close contact with each other, and a slot excitation feed line 7
The slot 3 excited by the radiating element 1 further excites the radiating element 1.

Therefore, if the sizes of the slot 3 and the radiating element 1 are selected so that they resonate at the desired frequency f, the radiating element 1 will radiate a linearly polarized electromagnetic wave with an electric field component in the y direction. . Furthermore, if the radiating element feed line 2 is connected to the edge portion of the radiating element 1 in the polarization direction, and then the linearly polarized radiating element 4 that resonates at the same frequency is connected so that the polarization planes match, the micro The basic connection of the strip array antenna unit antenna can be configured.

In the first embodiment shown in the first drawing, the shape of the radiating element 1 is a rectangular patch, but a circular patch or the like may also be used. The slot 3 may be a coupling opening, such as a circular shape. In addition to the illustrated microstrip line, a shielded planar circuit such as a strip line or a waveguide can be used as the slot excitation feeder line 7.

FIG. 3 is a plan view (a) and a cross-sectional view (b) showing the positional relationship when each part of the first embodiment is laminated. The radiating element 1 is formed by etching or the like on an antenna substrate (radiating element substrate) 5 having a relatively low dielectric constant (εr+). The length of the radiating element 1 is selected to be approximately λg / 2 (λg = c / (f - F -), where C is the speed of light and f is the desired resonant frequency) in the case of a boat-mounted microstrip antenna. However, when excited by the slot 3 provided at the bottom of the radiating element,
It is necessary to make the radiating element size slightly smaller than λg/2. Since the band characteristics of the radiating element depend on the substrate thickness d1, the substrate thickness is selected depending on the application. Further, in the case of a linearly polarized wave element, the width W9 can be arbitrarily selected. In this embodiment, the metal foil 6 serves as a common ground for the radiating element 1, the radiating element feed line 2, and the slot excitation feed line 7. A portion of this metal foil 6 corresponding to the radiating element 1 has a width Wa and a length L.
Form slot 3 of a. It is necessary to select the width Wa and the length La so that the slot 3 also resonates at the frequency f. The metal foil 6 may be made of copper foil or aluminum foil, or the antenna substrate 5 may be coated with copper on both sides and etched on both sides.

The feeder line 7 for slot excitation has a feeder board 8 (relative dielectric constant ε
, 2, thickness dz) by etching or the like. Since the length Ls portion of the slot excitation feeder line 7 operates as an open stub, it needs to be adjusted to an appropriate length to ensure matching.

FIG. 4 is a diagram showing the configuration of a second embodiment according to the present invention,
A radiating element 1, a radiating element feed line 2, a slot 3,
It includes a circularly polarized wave radiating element 9. In this example, a circularly polarized wave radiating element 9 is connected to a radiating element 1 which is circularly polarized excited by two slots 3 to form a circularly polarized wave array. The length of the radiating element feed line 2 is selected so that each radiating element is in phase at the desired frequency. In this case, as the radiating element, in addition to the illustrated rectangular patch, a circular patch or the like can also be used.

FIG. 5 is a partial configuration diagram of the second embodiment.

In order to excite the radiation element 1 in the X and Y directions, two slots 3 are formed in the metal foil 6. A circularly polarized antenna can be constructed by making the shape of the radiating element 1 square and exciting the two slots so as to give the same amplitude and a phase difference of 90 degrees.

Furthermore, by connecting the circularly polarized antenna 9 to the radiating element 1, a circularly polarized microstrip array antenna can be constructed.

(Effects of the Invention) A feature of the present invention is that a series-parallel microstrip array is constructed by further connecting a radiating element to a radiating element excited by a coupling opening such as a slot. The number of radiating elements as an array antenna can be adjusted by the number of radiating elements to be connected. In addition, since an array antenna can be configured around the radiating elements excited by the slot, the feeder line for exciting the slot does not become complicated, freeing up space on the feeder board, and making it easy to incorporate active elements. Become.

Therefore, it is considered to be an effective structure for active antennas and phased array antennas that incorporate elements such as amplifiers and phase shifters in the feed line.

In the present invention, power is fed to the array antenna directly by electromagnetic coupling to the radiating element, so the power due to the coupling is not radiated directly into space from the slot, but is transmitted to the radiating element and further connected to it. transmitted to the radiating element. As a result, the antenna efficiency is improved, and the radiation directivity characteristics of the antenna are not disturbed by unnecessary radiation. Furthermore, since the feed line board and the radiating element board are separated, the feed line and the radiating element can be designed and manufactured independently, increasing the degree of freedom in design. Furthermore, there is no need to connect both substrates with a through hole or the like, and manufacturing is easy.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of a first embodiment of the present invention, FIG. 2 is a partial configuration diagram of an embodiment of a tube 1 of the present invention, and FIG. 3 is a diagram of each part of an embodiment of the tube 1 of the present invention. A plan view showing the positional relationship of (
a), a sectional view (b), and FIG. 4 are basic configuration diagrams of the second embodiment of the present invention. FIG. It is a figure showing one example. ■...Radiating element 2...Feeding line for radiating element 3...Slot 4...Linear polarization radiating element 5...Radiating element substrate 6...Metal foil 7...
...Feeder line for slot excitation...Feeder board 9...Circularly polarized wave radiating element. Figure 1: Reiho Chin Bottom Figure 2: Oq Somei No. 1 - Igu 11's Anatomy of the 11th Traumatization (β)
Figure 3 Figure 4: 1 wealth 1 of Shishiki Tsunekin'l heir, y series oily face Figure 4 1 toshito sail 1; 1 piece figure 5

Claims (1)

[Claims] 1. A radiating element substrate on which a plurality of radiating elements are arranged in an array, a feed line substrate having a coupling opening excitation feed line on the substrate, and these substrates. In an electromagnetically coupled microstrip array antenna equipped with a metal foil interposed between the antennas and a metal foil having a coupling opening, coupling between two adjacent unit antennas each including one radiating element is achieved by coupling between two adjacent unit antennas each including one radiating element. A feeding line for the radiating element on the radiating element board connected to the radiating element, a coupling opening provided in the metal foil for exciting only one radiating element, and a coupling opening on the feeding line board for exciting the feeding line. A microstrip array antenna characterized in that it is configured to be achieved through. 2. The microstrip array antenna according to claim 1, wherein the coupling opening is slot-shaped.