Microstrip patch antenna in cavity-backed structure including via-hole

A microstrip patch antenna includes a via-hole pad including via-holes, a patch disposed on the via-hole pad, a feeding via-hole disposed at a side of the patch through the patch and the via-hole pad, and a shorting via-hole disposed at a side of the patch, and configured to connect the patch and a ground unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 USC 119(a) of Korean Patent Application No. 10-2013-0141459, filed on Nov. 20, 2013, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes.

BACKGROUND

The following description relates to a microstrip patch antenna in a cavity-backed structure including a via-hole.

2. Description of Related Art

A microstrip patch antenna is used for configuring an antenna on a common plane. Since the microstrip patch antenna has a half-wavelength, for example, a length of λ/2, reducing a size of the microstrip patch antenna may be difficult. When a ground unit of the microstrip patch antenna has a size similar to a size of a patch, an operational frequency transition may occur.

SUMMARY

In one general aspect, there is provided a microstrip patch antenna including a via-hole pad including via-holes, a patch disposed on the via-hole pad, a feeding via-hole disposed at a side of the patch through the patch and the via-hole pad, and a shorting via-hole disposed at a side of the patch, and configured to connect the patch and a ground unit.

The ground unit may be disposed at a distance from the patch that is less than or equal to a thickness of a substrate.

The via-hole pad may be disposed on a layer identical to that of the patch.

The microstrip patch antenna may further include a feed line connected to the patch via the feeding via-hole.

The patch may have a length less than a quarter of a wavelength in an operational frequency of the microstrip patch antenna.

In another general aspect, there is provided a microstrip patch antenna including a via-hole pad including via-holes, a patch disposed on the via-hole pad, and a ground unit disposed below the via-hole pad at a distance from the patch that is less than or equal to a thickness of a substrate on which the microstrip patch antenna is disposed.

The microstrip patch antenna may further include a shorting via-hole disposed at a side of the patch through the patch and the via-hole pad to the ground unit, and configured to connect the patch and the ground unit.

The microstrip patch antenna may further include a feeding via-hole disposed at a side of the patch through the patch and the via-hole pad to a feed line, and configured to feed from the feed line to the patch.

The via-holes may be disposed at a boundary of the microstrip patch antenna.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the systems, apparatuses and/or methods described herein will be apparent to one of ordinary skill in the art. Also, descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted for increased clarity and conciseness.

Unless indicated otherwise, a statement that a first layer is “on” a second layer or a substrate is to be interpreted as covering both a case where the first layer is directly contacts the second layer or the substrate, and a case where one or more other layers are disposed between the first layer and the second layer or the substrate.

The spatially-relative expressions such as “below”, “beneath”, “lower”, “above”, “upper”, and the like may be used to conveniently describe relationships of one device or elements with other devices or among elements. The spatially-relative expressions should be understood as encompassing the direction illustrated in the drawings, added with other directions of the device in use or operation. Further, the device may be oriented to other directions and accordingly, the interpretation of the spatially-relative expressions is based on the orientation.

FIG. 1is a diagram illustrating an example of a microstrip patch antenna including a cavity-backed structure. Referring toFIG. 1, the microstrip patch antenna includes a via-hole pad110, a patch120, a shorting via-hole121, a feeding via-hole123, a ground unit130, and a feed unit140.

The via-hole pad110corresponds to the cavity-backed structure, and includes a plurality of via-holes including a via-hole115at a boundary of the microstrip patch antenna.

The patch120is disposed on the via-hole pad110. A length of the patch120may be less than a quarter of a wavelength, for example, λ/4, in an operational frequency of the microstrip patch antenna.

Three types of via-holes are used in the microstrip patch antenna. The three types of the via-holes include the via-hole115of the cavity-backed structure at the boundary of the microstrip patch antenna, the shorting via-hole121to be used to connect the patch120disposed on an upper plane of the microstrip patch antenna and the ground unit130disposed on a lower plane of the microstrip patch antenna, and the feeding via-hole123to be used to feed from the feed unit140to the patch120.

The shorting via-hole121is disposed at a side of the patch120, and penetrates through the patch120and the via-hole pad110to the ground unit130. The shorting via-hole121may be filled with metal to connect the patch120disposed on the upper plane of the microstrip patch antenna and the ground unit130disposed on the lower plane of the microstrip patch antenna. The shorting via-hole121may be provided in a single form or a plural form. The shorting via-hole121may be disposed at an upper portion of the patch120such that the length of the patch120is less than λ/4 in the operational frequency of the microstrip patch antenna.

The feeding via-hole123is disposed at a side of the patch120, and penetrates through the patch120and the via-hole pad110to the feed unit140. The feeding via-hole123may be filled with metal to feed from the feed unit140to the patch120. The feeding via-hole123may be provided in a single form or a plural form.

The ground unit130may be disposed below the via-hole pad110at a distance from the patch120that is less than or equal to a thickness of a substrate on which the microstrip patch antenna is installed or disposed. That is, a gap between the patch120and the ground unit130may be less than or equal to the thickness of the substrate including the microstrip patch antenna, and thus, an energy field may be concentrated between the patch120and the ground unit130at an edge of the microstrip patch antenna. Various dielectric substances, for example, FR-4, Teflon, and/or a ceramic may be used as a material forming the substrate on which the microstrip patch antenna is installed or disposed.

The feed unit140feeds to the microstrip patch antenna, and includes a feed line145to be used to feed to the microstrip patch antenna. The feed line145may be, for example, a coplanar waveguide with ground plane (CPWG).

In this example, a size of the microstrip patch antenna is reduced using the via-holes, and adopts the cavity-backed structure around the microstrip patch antenna. Accordingly, a change in the operational frequency of the microstrip patch antenna that results from changes in a size of the ground unit130and a surrounding environment may be reduced, and degradation in emission efficiency of the microstrip patch antenna when compared to a conventional antenna may be reduced.

FIG. 2is a diagram illustrating an example of a pattern for each layer of the microstrip patch antenna ofFIG. 1. Referring toFIG. 2, the microstrip patch antenna includes a first layer210, a second layer230, and a third layer250. The microstrip patch antenna may include three layers or two layers.

The first layer210may correspond to a top plane, and includes a patch (e.g.,120ofFIG. 1) configuring the microstrip patch antenna.

The second layer230may correspond to an intermediate plane, and may include a metal pattern disposed at a boundary of the second layer230. The metal pattern may be disposed at a distance less than a substrate height (thickness) h, from a surface of the patch and to a boundary of a substrate.

The second layer230may include a via-hole pad (e.g.,110ofFIG. 1) including a plurality of via-holes (e.g., the via-hole115ofFIG. 1) disposed at the boundary of the second layer230. The via-hole pad may be configured without the second layer230, and may be disposed on the first layer210when the second layer230is absent.

The third layer250includes a feed line (e.g.,145ofFIG. 1), for example, a CPWG line, and a ground unit (e.g.,130ofFIG. 1). The third layer250may correspond to a bottom plane.

The feed line is extended from a boundary of the microstrip patch antenna to a vicinity of a feeding via-hole (e.g.,123ofFIG. 1) so as to be connected to the patch of the first layer210and to feed to the microstrip patch antenna. In an example, the microstrip patch antenna may be directly fed using a connector, and the feed line145may be unnecessary in this example.

FIG. 3is a diagram illustrating an example of electric field distribution in a microstrip patch antenna including a non-cavity-backed structure. Referring toFIG. 3, in the conventional microstrip patch antenna including the non-cavity-backed structure, an electric field may be distributed among a patch320in an upper portion of the microstrip patch antenna, a ground unit330on an antenna substrate, and a test board310disposed below the ground unit330. A fringing field occurs between the patch320and the ground unit330.

In detail, when a patch antenna is designed, a desired frequency may be emitted using a patch having a length less than λ/2 due to a length increment caused by a leakage electric field. In the example ofFIG. 3, an electric field of the patch320is uniform widthwise. Lengthwise, a frequency may fluctuate when the strongest electric field is satisfied on ends of both sides of the microstrip patch antenna. Thus, a fringing effect may be considered with respect to a lengthwise boundary. The fringing field may indicate an electric field distributed in a boundary of an antenna element, and may contribute to radiation of energy. In an operational frequency of the microstrip patch antenna, each phase of fields on the ends of both sides of the microstrip patch antenna may become identical, and the fringing field may be merged, thereby radiating an electromagnetic wave.

FIG. 4is a diagram illustrating an example of electric field distribution in a microstrip patch antenna including a cavity-backed structure. Referring toFIG. 4, in the microstrip patch antenna, a ground unit430is disposed at a distance less than a substrate height (thickness), for example, h, from a surface of a patch420.

In this example, it may be difficult for a fringing field to occur with a main substrate including a test board410disposed below a ground unit430, and formed with the ground unit430disposed below and connected to the patch420, using a shorting via-hole440, as discussed above. Thus, dielectric loss caused by a dielectric occurring on a back side of the antenna may be reduced.

In general, characteristics of an antenna may vary based on a size and a shape of a ground. In this example, the antenna may not be significantly influenced by conditions of the ground since the antenna is designed to prevent the ground unit430from an influence of the electric field. Also, in an example, a shorted patch antenna may be configured using a shorting pin, thereby reducing a length of a patch by λ/7.