Antenna and portable device having the same

An antenna apparatus and a portable device having the same are provided. The antenna apparatus includes a main antenna having a first radiator pattern, and an auxiliary antenna separated from the main antenna by a metal surface adjacent to the main antenna. The auxiliary antenna is resonant at a resonant frequency which is a function of at least one capacitor provided in a cut-out area of a printed circuit board (PCB) adjacent to the metal surface.

CLAIM OF PRIORITY

This application claims the benefit under 35 U.S.C. §119(a) of a Korean patent application filed on Jan. 23, 2013 in the Korean Intellectual Property Office and assigned Serial No. 10-2013-0007232, the entire disclosure of which is hereby incorporated by reference.

BACKGROUND

Technical Field

The present disclosure relates generally to an antenna and a portable device having the same, and more particularly, to a multi-band antenna configured for disposition in a limited space structure of the portable device.

Description of the Related Art

In general, a portable device is an electronic device in which a user can perform wireless communication with another party while hand-held. Recent portable devices have advanced to configurations which are small, thin, and lightweight in consideration of portability, along with advances in multimedia that can perform various functions.

Particularly, there is a need to provision capability for multi-band communication in today's portable devices, to transmit/receive RF signals of various types and protocols, e.g., various multimedia environments and Internet environments, while maintaining a small size and light weight. Multi-band capability is needed for communication of high speed data signals in addition to a traditional telephony function.

A typical portable device includes a data input and output device, a speaker, a microphone, and an antenna, among other electronics. Recent designs employ an internal antenna rather than an external antenna, for convenience and reliability. Conventionally, because a telephony dedicated communication antenna and a data communication antenna were shared, even if one antenna radiator was used, the packaging problem was not a severe one. However, as multimedia related data communication increases, it is difficult to provide a multiple service with one telephony dedicated communication antenna, and thus a data communication exclusive antenna is needed. Further, as a communication method develops from a presently widely used 3G communication method to a 4G Long Term Evolution (LTE) communication method, a 4G communication antenna is separately added and thus the number of antennas mounted in the portable device increases. Thereby, antenna allocation space for each antenna in the portable device is reduced. As such, it is difficult to package multiple antennas in the constrained space within the portable device.

Accordingly, due to the ongoing desire for small, lightweight and thin portable devices with high functionality, there is a need for an antenna meeting requisite performance in as small of an internal space within the portable device as possible.

SUMMARY

The present disclosure provides embodiments of an antenna apparatus and a portable device having the same, which have multiple antennas within the portable device operable at different bands and are capable of preventing a distortion phenomenon of an antenna characteristic due to interference between antennas.

In an embodiment, an antenna apparatus in a portable device includes a main antenna having a first radiator pattern, and an auxiliary antenna separated from the main antenna by a metal surface adjacent to the main antenna. The auxiliary antenna is resonant at a resonant frequency which is a function of at least one capacitor provided in a cut-out area of a printed circuit board (PCB) adjacent to the metal surface.

In an embodiment, a portable device with an antenna apparatus includes a PCB having first and second cut-out areas formed adjacent to an uppermost level metal layer, and at least one lower metal layer separated from the uppermost layer by a dielectric layer. A main antenna is disposed at the first cut-out area, and has a first radiator configured for operation at a first resonant frequency. An auxiliary antenna includes at least one capacitor, the auxiliary antenna is disposed at the second cut-out area, and is configured to resonate at a second resonant frequency which is a function of the at least one capacitor. The auxiliary antenna radiates through a ground surface at a periphery of the second cut-out area.

In an embodiment, an antenna apparatus provided in a portable device includes a main antenna that radiates an RF (radio frequency) signal supplied from a PCB, the RF signal being transferred between the PCB and a metal pattern radiator of the main antenna disposed on a first side of the PCB. At least one capacitor is connected on one side thereof to a ground surface that at least partially encloses a second cut-out area formed in a partial area of the PCB on an opposite side of the PCB. An auxiliary antenna is supplied an RF signal from the PCB through an RF feed point, transfers the signal to the capacitor, and transmits and receives an RF wave through a path returning to a ground surface of the PCB via the at least one capacitor. The auxiliary antenna transmits and receives an RF wave of a resonant frequency band which is a function of the capacitor.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The same reference numbers are used throughout the drawings to refer to the same or like parts. The views in the drawings are schematic views only, and are not intended to be to scale or correctly proportioned. Detailed descriptions of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present disclosure.

In an exemplary embodiment of the present disclosure, a portable device can be any of a variety of information, communication devices and multimedia devices such as a smart phone, a tablet personal computer (PC), a mobile communication terminal, mobile phone, a personal digital assistant (PDA), an international mobile telecommunication 2000 (IMT-2000) terminal, a code division multiple access (CDMA) terminal, a wideband code division multiple access (WCDMA) terminal, a global system for mobile communication (GSM) terminal, a general packet radio service (GPRS) terminal, an enhanced data GSM environment (EDGE) terminal, a universal mobile telecommunication service (UMTS) terminal, a digital broadcasting terminal, and an automated teller machine (ATM).

FIG. 1is a cross-sectional view illustrating a printed circuit board (PCB) for forming or mounting an antenna apparatus according to an exemplary embodiment of the present disclosure, andFIG. 2is a plan view illustrating a structure of an example antenna apparatus according to an exemplary embodiment of the present disclosure.

Referring toFIGS. 1 and 2, a portable device105according to the present exemplary embodiment includes an antenna apparatus1000comprised of a main (first) antenna100and an auxiliary (second) antenna200.

The main antenna100and the auxiliary antenna200have different configuration types and may have different principles of radiation. Antennas100and200may be disposed in a lower end portion of a printed circuit board (PCB) provided within the portable device. For example, the antennas100,200may be laterally offset in a width direction W of the portable device, as shown inFIG. 2.

The PCB10may be a multi-layer board, i.e., a board of a stacked structure in which a dielectric layer13and a metal plating layer15are alternately stacked in a repetitive fashion, as shown inFIG. 1. Dielectric layer16is directly below uppermost plating layer17. An area in which a portion of an uppermost level metal plating layer17of the PCB10is removed is referred to as a cut-out area. Areas111and210inFIG. 2are example cut-out areas.

The main antenna100is formed in the vicinity of such a cut-out area111to prevent radiating gain efficiency from deteriorating by a peripheral metal body. The cut-out spaces of the cut-out area provide separation between the conductive material of the antenna and neighboring metal of other components. As the metal plating layer, a metal material such as gold, silver, copper, nickel, and aluminum may be used, but from a cost viewpoint, copper is preferable.

The auxiliary antenna200is adjacent to the main antenna100in a lateral direction and is disposed in the cut-out area210formed on a portion of the uppermost level metal plating layer. In this example, main antenna100and the auxiliary antenna200are separated by a metal surface130.

The metal surface130is an uppermost level metal plating layer of the PCB, and is referred to as an area other than the cut-out area111of the main antenna100and the cut-out area210of the auxiliary antenna200. Metal surface130functions as a ground surface of the main antenna100and the auxiliary antenna200. In the example, a right-most portion97of antenna100is electrically connected to a side of surface130so as to provide a shunt reactance for tuning to achieve a desired resonance. (Although a solid line is shown separating the portion97of antenna100and the side of surface130, the surface130may be continuous with the portion97.)

The main antenna100transmits and receives radio frequency (RF) waves (e.g., UHF or microwave) through a metal pattern in which power is supplied. Hereinafter, the metal pattern is referred to as a radiator pattern or just “radiator”.

An RF signal is transferred from an RF circuit (not shown) of PCB10to radiator120through a power supply connection110, and is transmitted as an electromagnetic wave from device105as a result of the resonance properties of antenna100. A resonant frequency of the main antenna100is a function of an entire length of the radiator pattern120, a horizontal length and a vertical length of the radiator pattern120, and a dielectric constant of the PCB.

For example, as a length of the radiator pattern120is shortened, a resonant frequency of an antenna may be changed to a higher frequency, and as a length of the radiator pattern120is extended, a resonant frequency of an antenna may be changed to a lower frequency.

For example, the main antenna100may be formed as a planar inverted-F antenna (PIFA). The PIFA antenna is an antenna having a planar radiator element, as in a thin metal plate, and also having a radiator portion which is returned to PCB through a grounded portion, for the purpose of matching, thereby forming a structure resembling an inverted letter “F” (as seen at the right side portion95).

The main antenna100may be alternatively or additionally be an antenna formed by etching an antenna circuit to the PCB10, an antenna radiating through a radiator formed in a Z-axis direction of the PCB10(up-down direction inFIG. 1and direction through the paper inFIG. 2) by a connection of the PCB layer of a stacked structure and a via hole91, an antenna formed in a carrier by metal pattern plating, an antenna generated by rear fusion-bonding, an antenna formed using a flexible PCB (FPCB), laser direct structuring (LDS) antenna, and/or an antenna generated by an injection process of some other type. In the example ofFIG. 2, a via hole connection91connects top layer metal (composed of by uppermost layer17metal) with a lower layer metal15, thereby extending a radiator length of radiator pattern120.

The main antenna100may be at least one of an antenna having a frequency band of 1.56 GHz or more for Bluetooth (BT), a global positioning system (GPS), and WiFi and an antenna that performs communication of global system for mobile communication (GSM), code division multiple access (CDMA), and wideband code division multiple access (WCDMA).

The auxiliary antenna200employs at least one physical capacitor in a loop back structure, and thereby has a different structure and radiation principle than those of main antenna100. In particular, auxiliary antenna200is formed within the cut-out area210of the uppermost level metal plating layer17of the PCB10, and has a portion which connects to a ground surface133at a periphery of the cut-out area210. In the cut-out area210, at least one capacitor220, e.g., a chip capacitor, is provided.

The auxiliary antenna200transmits an RF signal provided from an RF transmitter (not shown) through a transmission line of PCB10, and when receiving an external signal, provides the receive signal to an RF receiver of PCB10. Antenna200is fed from PCB10at a feed connector230(interchangeably called “RF feed point” or “power supply connector” or the like). On transmit, an RF signal supplied from the PCB10is transferred to a capacitor220through the feed connector230, where the capacitor220is connected on another side (terminal or plate) thereof to the ground surface133, thereby being part of a return path to achieve resonance at a desired frequency. (Note that capacitor220is exemplified inFIG. 2as comprising three capacitors connected in series.) Auxiliary antenna200thereby has a driving characteristic that transmits and receives an electromagnetic wave at a resonant frequency band determined by the capacitance and physical structure of capacitor220.

Particularly, the auxiliary antenna200of the present exemplary embodiment is disposed at a location separated by a predetermined distance from the main antenna100by the metal surface130. Because radiation principles of the two antennas100and200are different, mutual interference between the two antennas100and200can be minimized.

That is, the main antenna100transmits and receives an electromagnetic wave through the radiator pattern120and has a resonant frequency determined by a length of the radiator pattern120. On the other hand, auxiliary antenna200transmits and receives an electromagnetic wave through the ground surface133that encloses the cut-out area210, and has a resonant frequency which is a function of the capacitance of at least one capacitor220provided in the cut-out area210.

“Capacitor220may receive power from the power supply connector230of the PCB at one side117(via current flow through ground surface133), and the other side115thereof is connected to the ground surface130as illustrated. In an alternative embodiment the other side117may be selectively connected to the ground surface133. That is, an optional switching circuit (not shown) may be included to selectively make a connection between the other side117of capacitor220and the ground surface133, e.g., in between the conductive line119(connected to ground surface133) and the capacitor side117.

When a shunt element240is connected to the power supply unit230, impedance of the capacitor220may be matched through the shunt element240, to achieve resonance at a desired frequency. Thus, the other side115may not be connected to the ground surface130. (That is, although the side115is shown connected to ground surface130inFIG. 2, this connection may be broken in an alternative embodiment for matching purposes.) For example, as the shunt element240, an inductor element may be used.”

In the example antenna apparatus ofFIG. 2, feed connector230is of a type having a triangular shape. A transmission line (not shown) of the PCB10has a signal line and a ground point. The base of the connector230triangle is electrically connected to the signal line through a via or the like (not shown), and the tip of the triangle is connected to the ground point of the same potential as surface133, as shown inFIG. 2. Auxiliary antenna200includes a radiating element113, which can be in the form of a wire or conductive line, having a first end connected to the base of the triangle and an opposite end connected to the first side115of capacitor220. The radiating element113may extend in approximately the lengthwise direction L of the portable device105, so as to make a connection to the capacitor220at a lower location of the PCB10. Shunt element240is shunted across the base of the triangle and the ground surface133. Another conductive line119has a first end connected to the opposite side117of capacitor220, and an opposite end118connected to the ground surface133. The first side115of capacitor220is connected through a shorter conductive line to the ground surface130at a point114.

Additional components93,94and95of device105, shown mounted on the top layer17of PCB10, may be unrelated to the antenna apparatus, and may or may not affect the performance characteristics of the exemplary antenna apparatus.

FIG. 3illustrates network analyzer data of the auxiliary antenna200in which resonant impedance in a band represents a changed state by the shunt element240connected to the power supply unit230.

The auxiliary antenna200can tune a resonant frequency of the auxiliary antenna200to a desired frequency range by adjusting capacitance of a plurality of capacitors220.

In other words, a resonant frequency of a corresponding antenna can be changed according to a quantity of capacitance. For example, when a quantity of capacitance increases, a low level band resonant frequency of the auxiliary antenna200moves to a high end of the band. Thus, by adjusting a connection structure of a capacitor and a value of capacitance, a resonant frequency of a low level band may be adjusted.

Particularly, the auxiliary antenna200is disposed at an area adjacent to the main antenna100of the present exemplary embodiment and can embody a multi resonant antenna of a different frequency band.

FIG. 4is a plan view diagram illustrating another exemplary embodiment of an antenna apparatus,1000′, in which an auxiliary antenna is embodied as a multi-resonant antenna. Antenna apparatus1000′ includes main antenna100and an auxiliary antenna400. Auxiliary antenna400according to the present exemplary embodiment may be formed with a plurality of auxiliary antennas300aand300bdisposed at a plurality of cut-out areas210and310, respectively.

Specifically, the first auxiliary antenna300adisposed at the first cut-out area210and the second auxiliary antenna300bdisposed at the second cut-out area310are described.

The first auxiliary antenna300adesigned to resonate at a relatively low frequency band is disposed at the interior of the portable device105′, and a second auxiliary antenna300bwhich resonates at a relatively high frequency band is disposed at the circumferential edge side of the portable device.

Because an antenna designed for a low frequency band should be allocated to an area wider than that of a higher frequency band antenna, it is preferable that the second auxiliary antenna300bof a high frequency band is disposed at the circumferential edge side of the portable device, and the first auxiliary antenna300aof a low frequency band is disposed toward the interior of the portable device.

A range of capacitors constituting the first auxiliary antenna300aand the second auxiliary antenna300bmay be formed to approximately 0.7 p-30 p, and in this case, a frequency band may be in a range of a low frequency band of 400 MHz to a high frequency band of 2G or more.

In the exemplary embodiment ofFIG. 4, the second auxiliary antenna300bis the same or similar in structure to the auxiliary antenna200ofFIG. 2, thus redundant discussion thereof is omitted. Auxiliary antenna300bincludes an RF feed connector330, shunt element340and radiator element130bwith the same or similar functions as in antenna200. The first auxiliary antenna300amay similarly include an RF feed connector and shunt element as shown, a radiator413connected between the feed connector and a first side415of at least one capacitor (three capacitors in series are exemplified). An opposite side419of the capacitor bank is connected to a ground surface130b. Note that the antenna apparatus1000′ includes a ground surface130′ which differs from the ground surface130ofFIG. 2by omitting a central section by virtue of the cut-out210. The ground surface130′ is considered to include three sections130a,130band130c, where section130cis an additional section providing a ground connection for the right side portion of antenna100. Section130bseparates the auxiliary antennas300a,300b. The first side315of the capacitor of antenna300bis connected to the right hand side of ground section130b. The second side419of the capacitor of antenna300ais connected to the left hand side of section130b. The first side415of the capacitor of antenna300ais connected to ground section130athrough at least one short conductive line that also connects to the opposite end of radiator413.

In the first auxiliary antenna300aand the second auxiliary antenna300b, because radiation is performed through the ground surface130bor133enclosing each cut-out area, even if the first auxiliary antenna300aand the second auxiliary antenna300bare adjacently positioned, radiation interference between these two antennas can be minimized. In this case, isolation of the first auxiliary antenna300aand the second auxiliary antenna300bmay be about −13 to −15 dB.

In this way, when embodying a multi resonant antenna using a capacitor as in the auxiliary antenna according to the present exemplary embodiment, a spatial restriction is not large and an auxiliary antenna can be additionally disposed at a periphery of the main antenna100, which is a PCB type antenna, whereby space can be effectively used.

FIGS. 5 to 8are plan views illustrating example structures of a multi resonant antenna according additional exemplary embodiments of the present disclosure.

FIG. 5illustrates an auxiliary antenna500in which a resonant frequency is determined by a plurality of capacitors510connected in a rail structure.

The capacitor510of a rail structure is disposed at a cut-out area formed in a portion of an uppermost level metal plating layer of the PCB. Capacitor510receives RF signal power from a power supply connector530which may be the same or similar as RF feed connector130described above; and a shunt element540may be connected in parallel across the signal line of connector530and ground surface133. A first end of a radiating element513is connected to the signal line of connector530. A pair of first ends515a,515bof the capacitor510is connected to the opposite end of radiating element513. A pair of second ends517a,517bof the capacitor510may be connected to a ground surface133.

The capacitor510has different capacitances and is formed with a plurality of capacitors C1-C6connected in parallel.

For example, the capacitor510is formed with a first capacitor group C1, C2, and C3and a second capacitor group C4, C5, and C6connected in parallel. It is preferable that capacitances of the first capacitor group C1, C2, and C3and the second capacitor group C4, C5, and C6are different.

A plurality of capacitors C1, C2, and C3constituting the first capacitor group are connected in series, and capacitances of each of the capacitors C1, C2, and C3may be the same or different.

A plurality of capacitors C4, C5, and C6constituting the second capacitor group are connected in series, and capacitances of each of the capacitors C4, C5, and C6may be the same or different.

For example, the first capacitor group C1, C2, and C3may be provided to embody a resonant frequency of a low frequency band of the auxiliary antenna500, and the second capacitor group C4, C5, and C6may be provided to embody a resonant frequency of a high frequency band of the auxiliary antenna500.

In this way, by a capacitor of a rail structure, i.e., a connection of a parallel structure of the first capacitor group and the second capacitor group having different capacitance, the auxiliary antenna500may become a multi resonant antenna having different resonant frequencies.

FIG. 6illustrates an auxiliary antenna600in which a resonant frequency is determined by a plurality of capacitors610connected in parallel by a radiator element613of a T structure.

The plurality of capacitors610are disposed at a cut-out area formed in a portion of an uppermost level metal plating layer of the PCB. The plurality of capacitors610receive the supply of power from an RF feed connector630which may be connected in parallel with a shunt element640. One end615of the plurality of capacitors610may be connected to the ground surface130, while the other end617is connected to the ground surface133.

The plurality of capacitors610have different capacitances and are formed with capacitors C7-C12connected in parallel. For example, the plurality of capacitors610may be formed with a third capacitor group C7, C8, and C9and a fourth capacitor group C10, C11, and C12disposed at the metal pattern613of a T structure.

Because a current is divided by the radiator element613of a T structure connected between the third capacitor group C7, C8, and C9and the fourth capacitor group C10, C11, and C12from the RF feed630, the third capacitor group C7, C8, and C9and the fourth capacitor group C10, C11, and C12become a structure connected in parallel.

It is preferable that capacitances of the third capacitor group and the fourth capacitor group are differently formed.

A plurality of capacitors C7, C8, and C9constituting the third capacitor group may be connected in series, and capacitances of each of the capacitors C7, C8, and C9may be the same or different.

A plurality of capacitors C10, C11, and C12constituting the fourth capacitor group may be connected in series, and capacitances of each of the capacitors C10, C11, and C12may be the same or different.

For example, the third capacitor group may be provided to embody a resonant frequency of a low frequency band of the auxiliary antenna600, and the fourth capacitor group may be provided to embody a resonant frequency of a high frequency band of the auxiliary antenna600.

In this way, by the third capacitor group and the fourth capacitor group connected in parallel by a metal pattern of a T structure and having different capacitances, the auxiliary antenna600may become a multi resonant antenna having different resonant frequencies.

FIG. 7illustrates an auxiliary antenna700in which a resonant frequency is determined by a plurality of capacitors710connected in parallel by a metal pattern713of a first modified T structure.

The plurality of capacitors710are disposed at a cut-out area formed in a portion of a uppermost level metal plating layer of the PCB and include a fifth capacitor group C13, C14, and C15and a sixth capacitor group C16, C17, and C18connected in parallel by the metal pattern713of a first modified T structure.

The fifth capacitor group and the sixth capacitor group supply power by different RF feeds733and735by the radiator element713of the first modified T structure, but are connected in parallel by sharing a ground line725.

That is, the fifth capacitor group and the sixth capacitor group are connected in parallel by a connection of a ground line shared by the commonly connected metal pattern of a first modified T structure and another power supply line.

The fifth capacitor group and the sixth capacitor group may supply power with different signal power levels by the separated power supply units533and535or may supply power with the same signal power level.

It is preferable that capacitances of the fifth capacitor group and the sixth capacitor group are differently formed.

A plurality of capacitors C13, C14, and C15constituting the fifth capacitor group may be connected in series, and capacitance of each of the capacitors C13, C14, and C15may be the same or different.

A plurality of capacitors C16, C17, and C18constituting the sixth capacitor group may be connected in series, and capacitances of each of the capacitors C16, C17, and C18may be the same or different.

For example, the fifth capacitor group may be provided to embody a resonant frequency of a low frequency band of the auxiliary antenna600, and the sixth capacitor group may be provided to embody a resonant frequency of a high frequency band of the auxiliary antenna600.

In this way, the auxiliary antenna700may become a multi resonant antenna having different resonant frequencies by the fifth capacitor group and the sixth capacitor group that supply power by the radiator element713of a first modified T structure and that share a ground line.

The separated power supply connectors733and735may be replaced with a single connector that divides and applies a signal power supplied from a power supply source (not shown) of the PCB to the fifth capacitor group and the sixth capacitor group.

FIG. 8illustrates an auxiliary antenna800in which a resonant frequency is determined by a plurality of capacitors810connected in parallel by radiator elements813and814of a second modified T structure.

The plurality of capacitors810are disposed in a cut-out area formed in a portion of a uppermost level metal plating layer of the PCB and include a seventh capacitor group C19, C20, and C21and an eighth capacitor group C22, C23, and C24connected by the radiators813and814of a second modified T structure.

The seventh capacitor group and the eighth capacitor group supply power by different power supply feeds833and835by the radiators813and814, respectively, of the second modified T structure, and are connected to a ground surfaces130and133, respectively.

That is, first ends of the seventh capacitor group and the eighth capacitor group are each connected to different power supply lines, and the opposite (second) ends thereof are each connected to the ground surface130or133.

The seventh capacitor group and the eighth capacitor group may supply power with different signal power levels or may supply power with the same power levels.

It is preferable that capacitances of the seventh capacitor group and the eighth capacitor group are differently formed.

A plurality of capacitors C19, C20, and C21constituting the seventh capacitor group may be connected in series, and capacitances of each of the capacitors C19, C20, and C21may be the same or different.

A plurality of capacitors constituting the eighth capacitor group may be connected in series, and capacitances of each of capacitors C22, C23, and C24may be the same or different.

For example, the seventh capacitor group may be provided to embody a resonant frequency of a low frequency band of an auxiliary antenna800, and the eighth capacitor group may be provided to embody a resonant frequency of a high frequency band of the auxiliary antenna800.

In this way, the auxiliary antenna800may become a multi resonant antenna having different resonant frequencies by means of the seventh capacitor group and the eighth capacitor group, which supply power by radiator elements813and814of a second modified T structure.

The separated power supply connectors733and735may be replaced with a combined connector that divides and applies signal power supplied from a power supply source (not shown) of the PCB to the seventh and eighth capacitor groups.

FIG. 9illustrates a measurement result of return (reflection) loss dB using a network analyzer for the auxiliary antenna200that embodies a multi resonant frequency via the at least one capacitor220ofFIG. 2. As can be seen from a measured result, the auxiliary antenna200according to the present exemplary embodiment may achieve a bandwidth of −5 dB (bandwidth in which return loss is at least 5 dB) embodies a wideband characteristic in dual bands over about 0.9 GHz-2 GHz.

FIG. 10illustrates a result that measures return loss dB using a network analyzer in the auxiliary antenna500that embodies a multi resonant frequency by the plurality of capacitors510connected in the rail structure ofFIG. 5. As can be seen from a measured result, the auxiliary antenna500according to the present exemplary embodiment may achieve a bandwidth of −5 dB over a wideband characteristic from about 0.9 GHz-2.1 GHz.

An auxiliary antenna of the present exemplary embodiment can obtain a resonant frequency desired by a user/portable device designer by adjusting capacitance via tuning a connection structure of the at least one capacitor using the above-described principles.

When disposing a multi antenna within a portable device having a small and narrow area, a configuration and disposition technology for a multi resonance of an auxiliary antenna adjacent to a main antenna of the present disclosure can enhance efficiency and allow for an antenna operating in various frequency bands.

As described above, in an antenna and a portable device having the same according to the present disclosure, by adjacently disposing an antenna in which a radiation principle and a structure are different, while preventing a distortion phenomenon of an antenna characteristic due to interference between antennas, mounting space of a multiple band antenna can be secured.

Further, according to the present disclosure, by adjusting capacitance of at least one capacitor, a resonant frequency of an antenna can be tuned to a desired frequency band.

Although exemplary embodiments of the present disclosure have been described in detail hereinabove, it should be clearly understood that many variations and modifications of the basic inventive concepts herein described, which may appear to those skilled in the art, will still fall within the spirit and scope of the exemplary embodiments of the present disclosure as defined in the appended claims.