EP1650830A1

EP1650830A1 - Circularly polarized patch antenna using metal patch and transceiving array antenna using the same

Info

Publication number: EP1650830A1
Application number: EP04258202A
Authority: EP
Inventors: Donghan Lee; Cheol-Sig Pyo; Jong-Suk Chae; Jong-Moon Lee
Original assignee: Electronics and Telecommunications Research Institute ETRI
Current assignee: Electronics and Telecommunications Research Institute ETRI
Priority date: 2004-10-21
Filing date: 2004-12-31
Publication date: 2006-04-26
Also published as: KR20060035942A

Abstract

Provided is a circularly polarized patch antenna using a metal patch and a transmitting/receiving array antenna.
The antenna can induce impedance matching and improve axial ratio by using a simple metal radiating patch and a reflection plate and improving the electromagnetic connection characteristics between the reflection plate and the radiating patch. It has a simple structure and it can be produced at a low cost. The circularly polarized patch antenna includes: a radiating unit which is positioned in the upper part of the antenna and has a metal patch for transmitting/receiving circularly polarized signals; a reflecting unit which is positioned in the lower part of the radiating unit with an air layer of a predetermined space from the radiating unit and eliminates rear radiation of the radiating unit; and a power feeding unit for supplying power to the radiating unit.

Description

Field of the Invention

The present invention relates to a circularly polarized patch antenna using a metal patch and a transceiving array antenna using the same; and, more particularly, to a probe feeding-type circularly polarized patch antenna using a metal patch of a simple structure, and a transceiving array antenna using the circularly polarized patch antenna.

Description of Related Art

Figs. 1A and 1B present a cross-section and a perspective view of a conventional circularly polarized patch antenna having a dielectric layer. As shown, the conventional circularly polarized patch antenna having a dielectric layer includes a conductive patch 11 formed on the upper surface of the dielectric layer 12 which uses a printed circuit board (PCB), a conductive ground layer 14 formed in the lower surface of the dielectric layer 12. Power is fed to the circularly polarized patch antenna by forming a via hole in the ground layer 14, the dielectric layer 12 and the patch 11 and inserting a connector 13 into the via hole.
In the conventional circularly polarized patch antenna which uses the dielectric layer, the flange part of the connector should be connected with the ground layer 14 of the array antennal through soldering. Therefore, the process and structure are complicated and the production cost is high. Therefore, the conventional circularly polarized patch antenna is not suitable for mass production.

Summary of the Invention

It is, therefore, an object of the present invention to provide a circularly polarized patch antenna which can induce impedance matching and improve axial ratio by using a simple metal radiating patch and a reflection plate and improving the electromagnetic connection characteristics between the reflection plate and the radiating patch. The circularly polarized patch antenna has a simple structure and it can be produced at a low cost.
It is another object of the present invention to provided a transceiving array antenna that can maintain impedance matching and axial ratio as much as a single patch antenna by arraying the circularly polarized patch antenna by using partitions, separating circular polarization into a left hand circular polarization and a right hand circular polarization, and using them as single patch antenna signals, individually.
In accordance with an aspect of the present invention, there is provided a circularly polarized patch antenna, which includes: a radiating unit which is positioned in the upper part of the antenna and has a metal patch for transmitting/receiving circularly polarized signals; a reflecting unit which is positioned in the lower part of the radiating unit with an air layer of a predetermined space from the radiating unit and eliminates rear radiation of the radiating unit; and a power feeding unit for supplying power to the radiating unit.
In accordance with another aspect of the present invention, there is provided an array antenna using circularly polarized single patch antennas, which includes: a plurality of circularly polarized single patch antennas including a radiating unit which is positioned in the upper part of the antenna and has a metal patch for transmitting/receiving circularly polarized signals; a reflecting unit which is positioned in the lower part of the radiating unit with an air layer of a predetermined space from the radiating unit and eliminates rear radiation of the radiating unit; and a power feeding unit for supplying power to the radiating unit in a probe feeding method; and an isolating unit which is positioned between the circularly polarized single patch antennas and prevents the circularly polarized single patch antennas from being coupled.

Brief Description of the Drawings

The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which:

Figs. 1A and 1B present a cross-section and a perspective view of a conventional circularly polarized patch antenna having a dielectric layer;
Figs. 2A and 2B present a cross-section and a perspective view of a conventional circularly polarized patch antenna having a metal patch in accordance with an embodiment of the present invention;
Figs. 3A and 3B present a cross-section and a perspective view of a transceiving array antenna using the circularly polarized patch antenna having a metal patch in accordance with an embodiment of the present invention;
Fig. 4 is a diagram describing a metal patch in accordance with the embodiment of the present invention;
Figs. 5A and 5B are graphs showing return loss of the circularly polarized patch antenna in accordance with the embodiment of the present invention;
Figs. 6A and 6B are graphs showing a return loss of the circularly polarized patch antenna in accordance with the embodiment of the present invention; and
Figs. 7A and 7B are graphs illustrating an axial ratio of the circularly polarized patch antenna in accordance with the embodiment of the present invention.

Detailed Description of the Invention

Other objects and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, which is set forth hereinafter.
Figs. 2A and 2B present a cross-section and a perspective view of a conventional circularly polarized patch antenna having a metal patch in accordance with an embodiment of the present invention.
As shown in Figs. 2A and 2B, the circularly polarized antenna using a metal patch, which is suggested in the present invention, includes a metal patch 21, a connector 23, and a refection plate 22. The metal patch 21 is set up in the upper surface of the antenna and radiates ultra-high frequency signals into free space. The connector 23 transmits power in the probe feeding method for circular polarization. The metallic refection plate 22 is set up in the lower surface of the antenna, suppresses rear radiation, and fixes the connector 23.
To convey the power by using the connector 23, a circular groove is formed in the reflection plat 22 as deep as the thickness of a dielectric substance surrounding a connector pin. The reflection plate 22 is put apart by a predetermined space 24 toward an air layer and then connected with the metal patch 21. The metal patch 21 also has a groove formed as deep as the thickness of a pin of the connector 23 and then it is connected with the reflection plate 22.
Impedance matching and the axial ratio can be improved by adjusting the space 24 between the reflection plate 22 and the metal patch 21. Also, radiation efficiency can be improved by removing the rear reflection that occurs in the metal patch 21 with the reflection plate 22.
Figs. 3A and 3B present a cross-section and a perspective view of a transceiving array antenna using the circularly polarized patch antenna having a metal patch in accordance with an embodiment of the present invention.
The circularly polarized patch antenna using a metal patch separates transmission from reception. In order to increase the transmission/reception separation, the single circularly polarized antennas using a metal patch of the present invention are arrayed in two-dimensional on a unit basis. The antenna includes a partition 25 which is located between the metal patches 21, prevents signal coupling during antenna radiation, and maintains the impedance matching and axial ratio the same as the single patch antenna.
Also, as illustrated in Fig. 3, when the antennas are arrayed, the power feeding location is made different in adjacent metal patches 21 to thereby generate left hand circular polarization and right hand circular polarization and suppress coupling between array unit antennas. Also, the separation between transmission and reception can be increased by using the left hand circular polarization and right hand circular polarization differently for a transmitting antenna and a receiving antenna.
In short, the left one of Fig. 3B is an antenna having the left hand circular polarization characteristic and the right one of Fig. 3B is an antenna having the right hand circular polarization characteristic. The partition 25 between the two antennas eliminates the coupling of the two antennas.
Fig. 4 is a diagram describing a metal patch in accordance with the embodiment of the present invention. As shown, the metal patch 21 is formed in the shape of a square with two diagonally facing corners being cut out, and the length of one side is 1/2 λ ₀. Herein, the characteristics of the metal patch 21 are different based on the length 25 of the cut-out edge and the location of the connector 23.
To be specific, the length 25 of the cut-out corner affects the impedance matching of a desired frequency and the axial ratio, and the location of the connector 23 affects the impedance matching.
Also, since the space 24 of the air layer between the reflection plate 22 and the metal patch 21 is related to the impedance matching and the axial ratio, the space 24 should be maintained properly. Herein, if the left hand circular polarization is needed, it is realized as shown in Fig. 4. If the right hand circular polarization is needed, the cut-out edge 25 is positioned in opposite or, as illustrated in the metal patch 21 on the right part of Fig. 3B, the cut-out edge 25 is maintained, and the location of the connector 23 is moved to the right.
Figs. 5A and 5B are graphs showing return loss of the circularly polarized patch antenna in accordance with the embodiment of the present invention. They show the return loss characteristics of the left hand circular polarization and the right hand circular polarization. Figs. 6A and 6B are graphs showing a return loss of the circularly polarized patch antenna in accordance with the embodiment of the present invention. They show radiation patterns of the left hand circular polarization and the right hand circular polarization. Figs. 7A and 7B are graphs illustrating an axial ratio of the circularly polarized patch antenna in accordance with the embodiment of the present invention. They show axial ratios of the left hand circular polarization and the right hand circular polarization.
As illustrated in the drawings, the circularly polarized patch antenna of the present invention has a 10dB return loss bandwidth characteristics of 3.5% (center frequency of 911MHz), a 3dB beamwidth characteristic of ±65°, and an antenna gain of 10dBi.
As described above, the present invention can realize a circularly polarized antenna having a simple structure by using a metal patch for radiation, a reflection plate, and a connector. The simple structure cuts down on the production cost, and simplifies the antenna assembly process. Therefore, the technology of the present invention is suitable for mass production.
The present application contains subject matter related to Korean patent application No. 2004-0084343, filed in the Korean Intellectual Property Office on October 21, 2004, the entire contents of which is incorporated herein by reference.
While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.

Claims

A circularly polarized patch antenna, comprising:
a radiating means which is positioned in the upper part of the antenna and has a metal patch for transmitting/receiving circularly polarized signals;

a reflecting means which is positioned in the lower part of the radiating means with an air layer of a predetermined space from the radiating means and eliminates rear radiation of the radiating means; and

a power feeding means for supplying power to the radiating means.
The circularly polarized patch antenna as recited in claim 1, wherein the power feeding means is of probe feeding.
The circularly polarized patch antenna as recited in claim 1, wherein the radiating means has a shape of a square metal plate with two diagonally facing corners being cut out by a predetermined length.
The circularly polarized patch antenna as recited in claim 1, wherein signals characteristics are realized into left hand circular polarization and right hand circular polarization by using the position of the cut-out corners of the radiating means or the coupling position of the radiating means and the power feeding means.
An array antenna using circularly polarized single patch antennas, comprising:
a plurality of circularly polarized single patch antennas including a radiating means which is positioned in the upper part of the antenna and has a metal patch for transmitting/receiving circularly polarized signals; a reflecting means which is positioned in the lower part of the radiating means with an air layer of a predetermined space from the radiating means and eliminates rear radiation of the radiating means; and a power feeding means for supplying power to the radiating means in a probe feeding method; and

an isolating means which is positioned between the circularly polarized single patch antennas and prevents the circularly polarized single patch antennas from being coupled.
The array antenna as recited in claim 5, wherein the isolating means is a partition.
The array antenna as recited in claim 5, wherein the radiating means has a shape of a square metal plate with two diagonally facing corners being cut out by a predetermined length in order to realize left hand circular polarization and right hand circular polarization.
The array antenna as recited in claim 7, wherein wherein different circular polarizations are used as a transmitting/receiving signal by using the radiating means or the coupling position of the radiating means and the power feeding means.