KR20020015694A - Flat-plate monopole antennae - Google Patents

Abstract

A monopole antenna includes a conductive ground plane, a conductive radiating plate, an antennae interface terminal, and a resonant network for defining operating characteristics of the antennae. The conductive radiating plate is spaced apart from the ground plane and, together with the ground plane, defines a cavity therebetween. The antennae interface terminal is in communication with the cavity and is electrically isolated from the ground plane and the radiating plate. The resonant network includes an inductive element electrically coupled between the interface terminal and the radiating plate. Preferably, the inductive element is disposed within the cavity and comprises a first air-core coiled wire inductor electrically coupled between the radiating plate and the interface terminal, and a second air-core coiled wire inductor electrically coupled between the interface terminal and the ground plane. Also, preferably each inductor has a number of wire turns, and the resonant network provides the antenna with a resonant frequency determined in accordance with the number of wire turns.

Description

Flat Monopole Antenna {FLAT-PLATE MONOPOLE ANTENNAE}

Conventional wireless communication devices, such as cellular phones, typically use a monopole antenna to send and receive electronic information. Conventional cellular monopole antennas comprise a tubular antenna element grounded in the case of a cellular phone and a metal rod disposed within the grounded tubular antenna element. In order to achieve the large gain and bandwidth characteristics required for cellular communication, a monopole antenna generally must be much longer than the cellular phone case length. Because long monopole antennas can limit the cellular phone's portability, monopole antennas are typically made of a telescoping series of monopole antenna sections that allow the monopole antenna to be inserted into the case when the cellular phone is not in use. However, monopole antennas must still be extended to achieve the gain and bandwidth characteristics required for cellular communication. Thus, attempts have been made to reduce the size of the monopole antenna without compromising antenna gain and bandwidth.

For example, Yokoyama (US 4,791,423) discloses a microstrip antenna suitable for use in mobile phones. The microstrip antenna comprises a first grounded rectangular conductive sheet, a radial rectangular conductive sheet parallel to the ground rectangular conductive sheet, and a feed pin disposed in a substrate between the first ground conductive sheet and the radiation conductive sheet. a feed pin) and second and second electrodes disposed at opposite ends of the first ground conductive thin plate and perpendicular to the first ground conductive thin plate and the radiation conductive thin plate sleeve to improve beam tilt characteristics of the antenna; And a third ground conductive thin plate. The second ground conductive thin plate functions as a connection conductive thin plate which connects the first ground conductive thin plate to the radiation conductive thin plate. In one variation, the patch antenna shown in FIG. 4A of the patent specification includes a planar passive element disposed in close proximity to the radiation conductive sheet to facilitate impedance matching of the antenna.

Nakase (US 5,061,939) discloses a flat panel antenna suitable for use in mobile phones. The planar antenna includes a rectangular conductive ground plate, a radial-shaped conductive top plate parallel to the ground plate, the ground plate and the substrate for electrically connecting the top plate to the ground plate. A plurality of elongated connecting members disposed between the top plate and a stripline resonator disposed between the ground plate and the top plate. The stripline resonator includes a feeder line and a capacitor electrode centered below the top plate to adjust the resonant frequency of the antenna.

Yokoyama (US 5,148, 181) discloses a mobile wireless communication device having an antenna that can prevent the gain of the antenna from being reduced by the user's head and / or hand while operating the communication device. The antenna is mounted on the upper surface of the case of the communication device, the rectangular first conductive plate, the rectangular second conductive plate disposed below and extending in parallel with the first conductive plate, the first and the And a third conductive plate extending perpendicular to the second conductive plate. The first conductive plate is spaced from the top surface of the communication device case. The antenna also includes a short circuit plate extending perpendicular to the first conductive plate and connected to an upper surface of the case close to the position of the handset and the user station of the user.

Both Yokoyama and Nakase's invention can provide antennas that are much smaller in size than conventional embedded monopole antennas. However, in each embodiment, the bandwidth, resonant frequency, and input impedance characteristics of the antenna are defined by fixed parameters such as the dimensions of the conductive plate and the distance between the conductive plates. As a result, more careful attention must be paid to manufacturing tolerances in order to obtain the proper operating characteristics of the monopole antenna. Thus, there is still a need for monopole antennas, which are much smaller than conventional monopole embedded antennas, whose operating characteristics are not compromised by changes from manufacturing tolerances.

<Start of invention>

According to the present invention, there is provided a radio communication apparatus and a monopole antenna capable of dealing with a defect of a monopole antenna in the prior art.

The monopole antenna according to the invention comprises a conductive ground plane, a conductive radiating plate, an antenna interface terminal, and a resonant network defining the operating characteristics of the antenna. The conductive radiating plate is spaced from the ground plate to define the cavity therebetween with the ground plate. An antenna interface terminal is in communication with the cavity and is electrically isolated from the ground plane and the radiating plate. The resonant network includes an inductive element electrically coupled between the interface terminal and the radiating plate.

A wireless communication apparatus according to the present invention includes a conductive case for receiving wireless communication hardware, a conductive radiation plate defining an antenna with a ground plane spaced apart from the case therein, and a resonant network defining an operating characteristic of the antenna. It includes. The conductive case includes an antenna communication unit for interfacing with the communication hardware. The resonant network includes an inductive element electrically coupled between the communication unit and the radiation plate.

In a preferred embodiment of the present invention, the inductive element is disposed in the cavity, the first air-core coil wire inductor electrically coupled between the radiating plate and the interface terminal, the interface terminal and the ground plane; And a second air-core coil wire inductor electrically coupled therebetween. Each inductor is wound with a plurality of wires, and the resonant network provides an antenna having a resonant frequency determined by the number of turns of the wire.

TECHNICAL FIELD The present invention relates to a planar antenna, and more particularly to a planar monopole antenna suitable for use in mobile wireless communications devices.

Preferred embodiments of the invention will now be described by way of example only with reference to the drawings.

1 is a perspective view of a wireless communication device in accordance with the present invention showing a conductive case (antenna ground plane), a radiation plate, and a resonant network.

FIG. 2 is an enlarged view of the top of the wireless communication device shown in FIG. 1, pointing to an air-core coil wire inductor of a resonant network.

3 is a longitudinal cross-sectional view as one variation of a wireless communication device including an arcuately-shaped radiation plate.

4 is a side view of another variation of a wireless communication device that includes a radiating plate angled with respect to the conductive case.

5A is a schematic diagram of a wireless communication device including dimension symbols used in the present invention.

5B is an enlarged schematic view of the top of a wireless communication device including additional dimension symbols used in the present invention.

Referring now to FIG. 1, a cavity defined between the conductive case 102, the conductive radiating plate 104 spaced from the case 102, and the case 102 and the radiating plate 104. A wireless communication device, shown generally at 100, is shown, including 106. Preferably, case 102 generally has a rectangular parallelepiped form configured to receive a wireless communication circuit therein, and includes a pair of opposing surfaces 108a, 108b, a pair of opposing sides 110a, 110b. And a pair of opposing ends 112a, 112b. In addition, the case 102 is preferably in the shape of a wireless telephone handset, and the wireless communication circuitry incorporated in the case 102 operates as a wireless telephone. However, as the applicant claims, the case 102 may be applied in other forms, and it will be appreciated that the wireless communication circuitry may function other than a wireless telephone.

As shown more clearly in FIG. 2, the case 102 includes an antenna communication unit 114 and an antenna interface terminal 116 extending through the communication unit 114. The interface terminal 116 extends into the cavity 106 and is electrically separated from the case 102 and the radiation plate 104. In addition, the interface terminal 116 interfaces with communication hardware disposed in the case 102, and enables the communication hardware to transmit and receive data as electromagnetic waves.

The radiation plate 104 may work with the case 102 to define a monopole antenna when the case 102 functions as a conductive ground plane for the antenna. Preferably, spinning plate 104 comprises a rectangular planar conductive plate made from copper or aluminum. However, radiating plate 104 may be applied to any other form suitable for proper antenna operation. For example, in one variation, the spinning plate shown in FIG. 3 is made arcuate. In addition, the spinning plate 104 may have the same or different dimensions as the case 102.

As shown in FIG. 1, the radiation plate 104 is preferably oriented substantially parallel to the case end 112 and inclined to the right with respect to the case face 108. However, the radiating plate 104 may also be arranged at different angles with respect to the case face 108, thus changing the antenna pattern of the monopole antenna. For example, in FIG. 4, the wireless communication device 100 ′ is shown with the end 112a ′ and the radiation plate 104 angled with respect to the case face 108. Alternatively, the spinning plate 104 may be slightly inclined with respect to the case end 112a.

As shown in FIGS. 1 and 2, the wireless communication device 100 also includes a resonant network 118 that defines the operating characteristics of the monopole antenna with respect to the dimensions of the radiating plate 104 and the cavity 106. Include. The resonant network 118 is disposed within the cavity 106 and includes an induction antenna element electrically coupled with the interface terminal 116, the radiating plate 104, and the case 102. However, the resonant network 118 is not limited to including only a single induction antenna element. For example, as one change (not shown), in order to increase the bandwidth of the antenna, the resonant networks 118 are each electrically connected to the interface terminals 1160 and each on the radiating plate and the case 102. It comprises a plurality of distinctive induction antenna elements positioned at.

The induction antenna element includes a first inductor 120 electrically connected between the radiating plate 104 and the interface terminal 116, and a second inductor electrically connected between the interface terminal 116 and the case 102. 122). Preferably, the first inductor 120 and the second inductor 122 are coupled together in a common core.

The resonant network 118 also includes a capacitive antenna element defined by the dimensions of the case 102, the radiating plate 104, and the cavity 106. The induction antenna element is disposed in parallel with the capacitive antenna element when the capacitive antenna element and the induction antenna element are collected to form a parallel resonance circuit. As can be seen clearly, the resonant frequency of the monopole antenna is determined by the capacitance of the capacitive antenna element and the inductance of the inductive antenna element.

Preferably, cavity 106 comprises an air cavity and inductors 120 and 122 include air-core coil wire inductors each having a respective number of wire turns, so that the resonant frequency of the monopole antenna is 120, 122) may be defined by the number of turns of the wire. Alternatively, the cavity 106 can include a dielectric or support structure that supports the radiation plate 104. In addition, the wires preferably used in the wire inductors 120 and 122 may include flexible wires such that the distance between the radiating plate 104 and the end 112a (and hence the capacitance of the capacitive antenna element) can be adjusted. Can be. In this way, the resonant frequency of the monopole antenna can adjust for problems due to variations in manufacturing tolerances.

As will be appreciated, the input impedance of a monopole antenna is defined by the number of wire turns (ie, inductance) of the wire inductors 120 and 122. On the other hand, the capacitance of the capacitive antenna element is defined by the size and shape of the radiation plate 104 and the case 102. Thus, the present invention allows the input impedance of the monopole antenna to match the impedance of the wireless communication circuit by adjusting the number of turns of the wire, while also changing the dimensions of the radiating plate 104 and / or case 102 of the antenna. It provides a significant advantage of allowing the resonant frequency and bandwidth to be adjusted as desired. In each case, however, the length and width of the radiation plate 104 and the end 112a are preferably kept at 10% or less of the operating wavelength of the antenna at the resonant frequency.

The following table describes the resonant frequency samples obtained by varying the dimensional change of the present invention in various ways. For reference, the symbols W, L, H, D, N1, and N2 are shown in FIGS. 5A, 5B as used below. Given that the antenna length of a conventional cellular phone is approximately 77 mm (operating in the GSM band), the following table demonstrates the significant size reduction that can be achieved with the present invention.

frequency W * L * H * D * N1 N2 type 850 MHz 47 23 9.5 4.2 0.6times 1.4times Cellular 1800 MHz 23 8 4.5 2.3 0.6times 1.4times PCS 850 MHz 37 20 10 5.2 0.5times 1.5times Cellular 1800 MHz 23 8 4.5 2.3 0.6times 1.4times PCS

* = All dimensions are in millimeters

The invention is defined by the claims appended hereto, and the foregoing description merely illustrates preferred embodiments of the invention. Those skilled in the art will be able to see certain additions, deletions, and / or modifications to the above-described description within the spirit and scope of the present invention, as not defined in the present invention but defined by the appended claims. have.

Claims (17)

In a flat-plate monopole antenna, Conductive ground plane, A conductive radiating plate spaced apart from the ground plane and defining a cavity therebetween with the ground plane; An antenna interface terminal in communication with the cavity and electrically separated from the ground plane and the radiation plate; A resonant network including an inductive element electrically connected with said interface terminal and said radiating plate, defining an operating characteristic of said antenna Flat monopole antenna comprising a. The planar monopole antenna of claim 1, wherein the ground plane, the radiating plate, and the cavity define a capacitive element, and the inductive element is disposed in parallel with the capacitive element. 3. A flat panel monopole antenna according to claim 1 or 2, wherein the inductive element is disposed in the cavity. 4. The inductive element according to any one of claims 1 to 3, wherein the inductive element is electrically connected between the radiating plate and the interface terminal and between the interface terminal and the ground plane. A flat monopole antenna comprising a second inductor coupled to the antenna. 5. A wireless communication device according to claim 4, wherein at least one of the inductors is an air-core inductor. In the wireless communication device according to claim 4, wherein the inductor includes a coil wire inductor wound around a plurality of times, and the resonant network provides the antenna with a resonance frequency determined according to the number of turns of the coil wire inductor. Wireless communication device. The wireless communication device according to any one of claims 1 to 6, wherein the resonant network comprises a plurality of separate inductive elements, each of which is electrically coupled to the interface terminal, each of which is positioned at the radiating plate. . 8. A wireless communications device according to any preceding claim wherein the radiation plate comprises an arcuate radiation plate. In a wireless communication device, A conductive case comprising an antenna communication section for receiving wireless communication hardware and interfacing therewith; A conductive radiation plate spaced apart from the case and defining an antenna together with the connection surface; A resonant network including an inductive element electrically coupled between the communication unit and the radiating plate to define an operating characteristic of the antenna Wireless communication device comprising a. 10. The wireless communication device of claim 9, wherein the case and the radiating plate define a capacitive element therebetween, and the inductive element is disposed parallel to the capacitive element. The wireless communication device according to claim 9 or 10, wherein the radiating plate and the ground plane together define a cavity therebetween, and the inductive element is disposed in the cavity. The said inductive element is a 1st inductor electrically coupled between the said radiation plate and the said communication part, and is electrically coupled between the said communication part and the said case. And a second inductor. 13. The wireless communications device of claim 12, wherein at least one of the inductors comprises an air-core inductor. The wireless communication device of claim 12, wherein each of the inductors includes coil wire inductors each of which is wound with a plurality of wires, and the antenna has a resonant frequency that is determined according to the number of times of winding of the coil wire inductor. 15. The wireless communication device according to any one of claims 9 to 14, wherein the resonant network comprises a plurality of unique inductive elements, each of which is electrically coupled to the communication unit, each of which is positioned on the radiating plate. 16. The wireless communication device according to any one of claims 9 to 15, wherein the case includes at least one face and the radiating plate is inclined with respect to the at least one face. 17. The wireless communication device according to any one of claims 9 to 16, wherein the radiation plate comprises an arcuate radiation plate.