Stacked patch antenna

Abstract

A stacked patch antenna (1) comprising at least an upper patch antenna (2) having a radiating element and a lower patch antenna (3) having a radiating element, wherein the upper patch antenna (2) is a cavity-backed patch antenna having a wall (4) that laterally surrounds the radiating element, the lower patch antenna (3) is a cavity-backed patch antenna having a wall (4') that laterally surrounds both the radiating element of the lower patch antenna (3) and the radiating element of the upper patch antenna, and the upper patch antenna (2) comprises a 1 / 4 wavelength shunt stub (5) as a parasitic element.

Description

Technical Field

[0001] The present invention belongs to the field of patch antennas which are arranged in a stacked manner and can be used, for example, in satellite communication. This stack includes at least an upper patch antenna and a lower patch antenna.

Background Art

[0002] There are several patent documents related to the technology of arranging patch antennas in a stacked manner. For example, Patent Document 1 discloses a stacked patch antenna including a plurality of patch antennas each having an operating frequency band arranged in a stacked manner, and each antenna includes a radiating conductive patch and a cable having a plurality of coaxial conductors separated from each other by a dielectric. The first conductor of this cable transmits the feeding signal of the uppermost antenna, conductively couples to the null point of its radiating conductive patch, and passes through the opening of the null point of the radiating conductive patch of the other antennas among the stacked antennas. Each of the antennas at successively lower positions in the stack is coupled to another one of the plurality of conductors of the cable, and that conductor connects the other patch to the ground. With this arrangement, a high degree of separation between the frequency operating bands is maintained. Although another antenna can be added between successive sets of the above-described antennas, in these antennas, due to parasitic coupling with the antenna above, they are fed by the same feeding conductor as the antenna above.

[0003] Patent Document 2 ("Stacked self-diplexed dual-band patch antenna") discloses an antenna having a conductive base. In some embodiments, the first radiating element may be located on the conductive base and may be operable in a first frequency band. The second radiating element may be located on the first radiating element and may have a smaller mounting area than the first radiating element. The second radiating element may operate in a second frequency band. The second radiating element may be located on the first radiating element at a distance such that the separation between the feed lines of the first and second radiating elements is 15 dB or more in the first and second frequency bands.

[0004] Patent Document 3 ("Self-multiplexing antennas") discloses a self-multiplexing antenna comprising a substrate, a first antenna element supported by the substrate, the first antenna element comprising a first antenna patch and a first antenna reflector, a first signal feed connected to the first antenna patch, and a second antenna element supported by the substrate, wherein the second antenna element is aligned at least partially perpendicular to the first antenna element, and the second antenna element comprises a second antenna patch and a second antenna reflector, a second signal feed connected to the second antenna patch, and a first isolation resonator between the second antenna reflector and the first antenna patch.

[0005] A diplexer is a device typically used to separate a signal into two frequency bands. Typically, in a stacked patch antenna, the electric field radiated by the lower antenna induces a surface current in the upper antenna, and the electric field radiated by the upper antenna induces a surface current in the lower antenna.

[0006] Therefore, there is a need to provide a stacked patch antenna with multi-frequency performance that enhances the degree of separation between frequency bands. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] European Patent No. 1341259 [Patent Document 2] U.S. Patent No. 20180358701 [Patent Document 3] U.S. Patent Application Publication No. 2019252800 [Overview of the Initiative]

[0008] The object of the present invention is to provide a stacked patch antenna that overcomes the aforementioned drawbacks. The present invention provides a stacked patch antenna comprising an upper patch antenna having at least a radiating element and a lower patch antenna having a radiating element, wherein the upper patch antenna is a cavity back patch antenna having a wall that laterally surrounds the radiating element, and the lower patch antenna is a cavity back patch antenna having a wall that laterally surrounds both the radiating element of the lower patch antenna and the radiating element of the upper patch antenna, and the upper patch antenna comprises a quarter-wavelength shunt stub as a parasitic element.

[0009] The concept of using a cavity back antenna inside another cavity back antenna offers a novel and compact design with high separation across multiple frequency bands and large circular polarization capability. Separation is improved by incorporating a quarter-wavelength shunt stub as a parasitic element into the upper patch antenna. This element reduces the effective cross-section, resulting in even higher separation. A quarter-wavelength shunt stub maximizes circular polarization capability because it achieves purer circular polarization and smoother axial ratio of coverage. While it's true that quarter-wavelength shunt stubs are not as readily available as circular patches, they can reduce leakage. This parasitic element achieves what other dielectric antennas achieve in terms of bandwidth gain. In terms of separation, this can be further improved by incorporating a concentric ring of step impedance on the contact surface of the upper antenna, resulting in extremely excellent separation capabilities.

[0010] Other features and advantages of the present invention will become apparent from the following detailed description of several embodiments illustrating its purpose in relation to the accompanying drawings. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows a perspective view of the stacked patch antenna of the present invention. [Figure 2] This figure shows a plan view of the stacked patch antenna shown in Figure 1. [Figure 3] This figure shows a cross-sectional view of a stacked patch antenna. [Figure 4] This figure shows a cross-sectional view of the stacked patch antenna of the present invention. [Modes for carrying out the invention]

[0012] The present invention discloses a stacked patch antenna 1, shown in different diagrams in Figures 1 to 4. As shown in the embodiments in Figures 1 to 3, the stacked patch antenna 1 comprises an upper patch antenna 2 having a radiating element and a lower patch antenna 3 having a radiating element. The upper patch antenna 2 is a cavity back patch antenna having a wall 4 that surrounds the radiating element laterally. The lower patch antenna 3 is a cavity back patch antenna having a wall 4' that surrounds both the radiating element of the lower patch antenna 3 and the radiating element of the upper patch antenna 2 laterally. The upper patch antenna 2 includes a quarter-wavelength shunt stub 5 as a parasitic element.

[0013] This arrangement of the stacked patch antenna 1 makes it possible to achieve a compact, integrated solution with a separation of over 20 dB.

[0014] By reducing the coaxial size and the size relative to the wavelength, two stacked cavity-back patch antennas are used, resulting in good separation between bands and the ability to operate simultaneously in two bands. This achieves low volume, low mass, and high performance.

[0015] A stacked cavity-back patch antenna can be used for transmitting and receiving telecommunications or for two transmitting signals (telecommunications or navigation). The degree of separation can be adjusted by rotating the quarter-wavelength shunt stub 5 with respect to the vertical axis (Z-axis). Furthermore, this parasitic element is used to provide better axial ratio flatness and significantly improves the purity of circular polarization for a single notched patch.

[0016] In one embodiment, the stacked patch antenna 1 further comprises a step impedance concentric ring (SICR) 6 on the ground surface of the upper patch antenna (as shown in Figure 4). These rings are used to provide better separation performance (fine-tuning). In the stacked patch antenna 1 of the present invention, the current generated by the lower patch antenna 3 does not flow into the upper patch antenna 2, and the current generated by the upper patch antenna 2 does not flow into the lower patch antenna 3. There is no current inflow or outflow, and there is no electromagnetic coupling between the patch antennas. A diplexer section for separating the bandwidths is unnecessary, saving mass. In one embodiment, the stacked patch antenna 1 is a completely metallic antenna that does not have a dielectric substrate.

[0017] This stack may include two or more patch antennas. Although the present invention has been fully described in relation to preferred embodiments, it is clear that it should not be considered limited by these embodiments, but rather limited by the following claims, and modifications may be introduced within that scope.

Claims

1. A stacked patch antenna (1) comprising an upper patch antenna (2) having at least an upper radiating element and a lower patch antenna (3) having a lower radiating element, wherein the lower patch antenna (3) is a cavity back patch antenna having a first wall (4') that laterally surrounds both the lower radiating element of the lower patch antenna (3) and the upper radiating element of the upper patch antenna (2), the upper patch antenna (2) is a cavity back patch antenna having a second wall (4) that laterally surrounds the upper radiating element, and the upper patch antenna (2) is characterized by comprising a cross-shaped stub (5) that is rotatable with respect to a vertical axis as a parasitic element.

2. The stacked patch antenna (1) according to claim 1, wherein the upper patch antenna (2) further comprises a step impedance concentric ring (6) on the ground surface of the upper patch antenna.

3. The stacked patch antenna (1) according to any one of claims 1 to 2, wherein the second wall (4) and the first wall (4') are cylindrical.

4. The stacked patch antenna (1) according to any one of claims 1 to 3, wherein the stacked patch antenna (1) is made entirely of metal.

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