Abstract: A multi-band antenna used in a portable electrical device can operate in WWAN. The multi-band antenna includes a PCB, a first antenna body, and a second antenna body. The PCB has a first surface and an opposite second surface and defines a through hole extending from the first surface to the second surface. The first antenna body is formed on the first surface of the PCB comprising a first radiating element and a first grounding element. The second antenna body is formed on the second surface of the PCB. The second antenna body comprises a second radiating element, a second grounding element, and a connecting element connecting the second radiating element and the second grounding element. The first radiating element and the second radiating element electrically connect with each other via the through hole of the PCB. A feeding line has an inner conductor electrically connecting to the first radiating element and an outer conductor electrically connecting to the first grounding element.

Abstract: A folding dipole antenna having remarkably multi-band characteristics as compared with prior art. Element width at the short portions (12d, 11d) of any one of an upper element (12) or a lower element (11) is set wider than that of the other element, and the element width at the long part of the upper element (12) or the lower element (11) on the feed side is set wider than that of the element on the non-feed side.

Abstract: An antenna having a number of operating frequencies includes a feed element, a ground element, and a number of conductive antenna tracks. The conductive antenna tracks extend outward from the feed element and return back to the ground element. When the conductive antenna tracks are located in a same plane, areas defined by the conductive antenna tracks are not overlapped with one another. When parts of the conductive antenna tracks are located in different planes, multiple frequency bands are formed respectively by multiple resonant frequencies corresponding to the conductive antenna tracks.

Abstract: The invention relates in part to a folded dipole having a dipole axis and a pair of arms which together have a profile which is concave on one side and convex on the other when viewed along the dipole axis. The dipoles may be arranged as a dipole box around a central region, typically in a generally circular or square configuration. Further elements may be placed in the dipole box or in the gaps between dipole boxes. The antenna may be a single-band antenna, or a multi-band antenna with the further elements operating in a different frequency band to the dipole boxes. The further elements may be concentric dipole boxes. The invention is particularly suited for use in a cellular base station panel antenna. A novel coaxial to microstrip transition is also described.

Abstract: An antenna structure (106) comprising a first electrically conductive element (102) having a first end and a second end, a second electrically conductive element (103) having a first end and a second end, and a coupling structure (104) short-circuiting the first electrically conductive element (102) with the second electrically conductive element (103) by means of electrically connecting the electrically conductive elements (102, 103) at positions between the first and the second ends, wherein an integrated circuit (105) is connectable between the first end of the first electrically conductive element (102) and the first end of the second electrically conductive element (103).

Abstract: A broadband dipole antenna includes a dielectric substrate, a first radiating portion, a second radiating portion, a substantially U-shaped or V-shaped feed gap, and two feed points. The feed gap is located in-between the first radiating portion and the second radiating portion. The two feed points are located in the first radiating portion and the second radiating portion, respectively, and separated by the feed gap.

Abstract: An RFID device including: electronic circuitry suitable for an RFID device comprising a radio frequency section; an antenna; a battery which provides the device with power; and at least one quarter wavelength transmission line coupled between the battery and one or both of the electronic circuitry and the antenna.

Abstract: According to one embodiment of the present invention, a dipole antenna capable of supporting multi-band communications, includes a first portion of the antenna in a folded structure, a second portion of the antenna that includes a first coupling pad and a second coupling pad physically separated by a distance, and a current path along the first portion of the antenna and the second portion of the antenna, wherein a first portion of the current path that includes the first coupling pad and the second coupling pad is configured to introduce a slow wave effect if electric current flows through the first portion of the current path.

Abstract: Methods and systems of attaching a radio transceiver to an antenna. At least some of the illustrative embodiments are systems comprising an antenna and an integrated circuit configured to operate as a radio transceiver. The antenna comprises a ground plane having a first edge surface, and an active element having a second edge surface. The ground plane and the active element are retained together such that the first and second edge surfaces are substantially coplanar and form an antenna edge. The integrated circuit is configured to operate as a radio transceiver, and the integrated circuit is mechanically coupled to the edge of the antenna and electrically coupled to the active element.

Abstract: A broadband antenna is capable of generating an upper resonant mode (at about 700 MHz) from a first radiating arm and a lower resonant mode (at about 500 MHz) from a second radiating arm. The first and second radiating arms are bent at least one time. An open end of the second radiating arm is extended toward an open end of the first radiating arm with a predefined distance there between. The predefined distance can be adjusted to improve the impedance matching of lower resonant mode, which can be further combined with the upper resonant mode to achieve a broad bandwidth covering the complete spectrum of digital TV channels (470-862 MHz).

Abstract: Disclosed is a folded dipole antenna device which is of an unbalanced feed type and includes an antenna element of approximately plate-like loop structure, connected to an antenna feed point and an antenna ground provided on a base plate. In the folded dipole antenna device, the antenna element of loop structure includes a pair of first element sections which extend approximately parallel to the base plate, a second element section formed by merging element sections that are folded back from both ends of the first element sections and extend approximately parallel to the first element sections, and a third element section which extends from a folded top part of the second element section toward the first element sections and an end part thereof is close to the first element sections.

Abstract: A folded dipole loop antenna has a matching circuit integrally formed therein. The antenna includes a radiating unit formed in the shape of a loop, and the matching circuit has an extended part projected and extended toward a central area of the radiating unit from an inner side surface of the radiating unit, thereby eliminating the need for a separate space for the matching circuit. The antenna can change a resonant frequency thereof by adjusting input reactance through the matching circuit.

Abstract: A device 20 includes a substrate 22 having an integrated circuit (IC) die 24 coupled thereto. A bond wire 28 interconnects a die bond pad 32 on the IC die 24 with an insulated bond pad 36. Another bond wire 38 interconnects a die bond pad 42 on the IC die 24 with another insulated bond pad 46. The bond wires 28 and 38 serve as radiating elements of a dipole antenna structure 64. A reflector 72 and director 74 can be located on the substrate 22 and/or the IC die 24 to reflect and/or direct a radiation pattern 66 emitted by or received by the antenna structure 64. A trace 82 can be interconnected between the insulated bond pads 36, 46 to form a folded dipole antenna structure 84.

Abstract: In a folded dipole antenna, both ends of a first dipole portion with a feeding portion are connected to both ends of a second dipole portion so that a slot portion may be formed, and the first and the second dipole portion have a width for generating a linearly-polarized wave in a slot mode (in a longitudinal direction) when an RFID chip is mounted on the feeding portion. A terminal of a chip is actually connected to an antenna terminal of the feeding portion of the folded dipole antenna to realize a tag.

Abstract: The present invention relates to a dual polarization broadband antenna having a single pattern, which is provide with a radiation device having a square structure, in which a plurality of folded dipole elements are formed in a single continuously-connected pattern, and a feeding portion for feeding signals to the plurality of folded dipole elements is formed on the radiation device. Accordingly, the plurality of folded dipole elements formed on the radiation device are connected in a single square and rectangular pattern, so that the structure thereof is simplified, with the result that the cost can be reduced. Furthermore, the feeding portion, that dually feeds signals, and the plurality of folded dipole elements, connected in a single pattern, are coupled, so that the dual polarization characteristic can be easily acquired.

Abstract: Aspects of a method and system for configurable antenna in an integrated circuit package are provided. In this regard, a phased array antenna embedded in a multi-layer integrated circuit (IC) package may be utilized for transmitting and/or receiving signals. An IC enabled to transmit and/or receive signals may be bonded to the multi-layer IC package and may communicate a reference signal and/or one or more phase shifted versions of said reference signal to the antenna. One or more phase shifters (fabricated, for example, in planar transmission line) may be embedded in the multi-layer IC package and may be controlled via an IC bonded to the multi-layer IC package. The phased array antenna may comprise a plurality of antenna elements which may each comprise an interconnection for communicatively coupling to an associated transmitter and/or receiver, a feeder line, a quarter wavelength transformer, and a radiating portion (e.g., a folded dipole).

Abstract: An antenna and a wireless mobile communication device incorporating the antenna are provided The antenna includes a first conductor section electrically coupled to a first feeding point, a second conductor section electrically coupled to a second feeding point and a near-field radiation control structure adapted to control characteristics of near-field radiation generated by the antenna. Near-field radiation control structures include a parasitic element positioned adjacent the first conductor section and configured to control characteristics of near-field radiation generated by the first conductor section, and a diffuser in the second conductor section configured to diffuse near-field radiation generated by the second conductor section into a plurality of directions.

Abstract: A collapsible interior antenna has a main antenna, two wing antenna assemblies and a secondary antenna. The main antenna is rectangular and has two opposite connecting edges. The wing antenna assemblies are pivotally mounted respectively on the connecting edges and connected transmittably to the main antenna. The secondary antenna is a telescopic antenna, receives signals having a different frequency band to the main antenna and is electrically mounted on the main antenna. A person can minimize a footprint of the collapsible interior antenna by retracting the secondary antenna and folding the wing antenna assemblies toward the main antenna. When in use, the wing antenna assemblies can be unfolded to receive signals from different directions.

Abstract: The present invention relates to a tag-use antenna allowing a miniaturization while maintaining a constant minimal change of a communication distance. The tag-use antenna has a feed part of a folded dipole antenna of a size of 53 mm long and 7 mm wide being connected to, and equipped with, an LSI chip of Rc=500 ohms and Cc=1.4 pF and is covered with plastic resin 13 of the dielectric constant ?r=3 and thickness of t=0.75 mm on both sides of the antenna. The dipole part of 1 mm wire path width of the tag-use antenna is formed in a rectangular spiral by being bent inward from both ends at bending parts at four places. The entire length of the dipole antenna when extending the four bending parts straight is featured so as to be shorter than one half of a resonance wavelength of the antenna. An inductance part is featured in the intermediate part of the both dipole parts in the neighborhood of the center of the antenna.

Abstract: A transmitting and receiving system including an antenna element having first and second current paths, and a meander feed line connected to said first and second current paths, the meander feed line including a radiating portion parallel to the first current path, wherein a current in the radiating portion is in a direction opposite of a current in the first current path, and wherein a current in the second current path is in a direction the same as the current in said radiating portion.

Abstract: The present invention relates to a tag-use antenna allowing a miniaturization while maintaining a constant minimal change of a communication distance. The tag-use antenna has a feed part of a folded dipole antenna of a size of 53 mm long and 7 mm wide being connected to, and equipped with, an LSI chip of Rc=500 ohms and Cc=1.4 pF and is covered with plastic resin 13 of the dielectric constant ?r=3 and thickness of t=0.75 mm on both sides of the antenna. The dipole part of 1 mm wire path width of the tag-use antenna is formed in a rectangular spiral by being bent inward from both ends at bending parts at four places. The entire length of the dipole antenna when extending the four bending parts straight is featured so as to be shorter than one half of a resonance wavelength of the antenna.

Abstract: A folded dipole antenna that transmits and receives radio frequency waves (RF) waves has two radiating strips that form a dipole. A metallic radiating element is located between the two radiating strips, facilitating an increase in the gain of the antenna. The folded dipole antenna may be used in a wireless communication device.

Abstract: The present invention aims at providing an antenna apparatus which enables switching directivity suitable for a plurality of usage patterns of a wireless terminal, such as that achieved during voice conversation and that achieved during data communication, and is easily slimmed down, as well as providing a wireless terminal using the antenna apparatus.

Abstract: An antenna particularly suitable for use in radio frequency identification (RFID) transponders. First and second half portions each include nominally straight conductive sections primarily defining a radiating characteristic and nominally spiral conductive sections creating a positive reactive characteristic of the antenna. The straight conductive sections have feed points for connecting the antenna into the RFID transponder, and further connect with the respective spiral conductive sections. The first and said second half portions characterize the antenna as being a dipole type, and adding an optional loop section connecting the straight conductive sections can further characterize it as being of a folded dipole type.

Abstract: An antenna and a wireless mobile communication device incorporating the antenna are provided The antenna includes a first conductor section electrically coupled to a first feeding point, a second conductor section electrically coupled to a second feeding point and a near-field radiation control structure adapted to control characteristics of near-field radiation generated by the antenna. Near-field radiation control structures include a parasitic element positioned adjacent the first conductor section and configured to control characteristics of near-field radiation generated by the first conductor section, and a s in the second conductor section configured to diffuse near-field radiation generated by the second conductor section into a plurality of directions.

Abstract: A device 20 includes a substrate 22 having an integrated circuit (IC) die 24 coupled thereto. A bond wire 28 interconnects a die bond pad 32 on the IC die 24 with an insulated bond pad 36. Another bond wire 38 interconnects a die bond pad 42 on the IC die 24 with another insulated bond pad 46. The bond wires 28 and 38 serve as radiating elements of a dipole antenna structure 64. A reflector 72 and director 74 can be located on the substrate 22 and/or the IC die 24 to reflect and/or direct a radiation pattern 66 emitted by or received by the antenna structure 64. A trace 82 can be interconnected between the insulated bond pads 36, 46 to form a folded dipole antenna structure 84.

Abstract: A circuit array, comprising a substrate (101), and comprising an electrically conducting folded dipole antenna (103) arranged on and/or in the substrate (101), the folded dipole antenna (103) having a first antenna connection (104) and having a second antenna connection (105), and wherein the folded dipole antenna (103) has a disconnected portion (108) dividing the folded dipole antenna (103) in a first antenna portion (109) and in a second antenna portion (110) such that a capacity (111) is formed at the disconnected portion (108) between the first antenna portion (109) and the second antenna portion (110), wherein an integrated circuit (102) can be or is arranged on the substrate (101), the integrated circuit (102) having a first integrated circuit connection (106) connected to the first antenna connection (104) and having a second integrated circuit connection (107) connected to the second antenna connection (105).

Abstract: A wireless communication device coupled to a wave antenna that provides greater increased durability and impedance matching. The wave antenna is a conductor that is bent in alternating sections to form peaks and valleys. The wireless communication device is coupled to the wave antenna to provide wireless communication with other communication devices, such as an interrogation reader. The wireless communication device and wave antenna may be placed on objects, goods, or other articles of manufacture that are subject to forces such that the wave antenna may be stretched or compressed during the manufacture and/or use of such object, good or article of manufacture. The wave antenna, because of its bent structure, is capable of stretching and compressing more easily than other structures, reducing the wireless communication device's susceptibility to damage or breaks that might render the wireless communication device coupled to the wave antenna unable to properly communicate information wirelessly.

Abstract: A multi-band antenna of compact size includes a conductor of uniform cross-section folded to form the antenna with a connection portion, a low-frequency first radiation portion, and a high-frequency second radiation portion. The connection portion has a feeding point for signal feeding. The first and second radiation portions connect to two ends of the connection portion. The first radiation portion is folded along two different planes to form three main sections. The second radiation portion is folded along a plane to form two sections. A terminal section of the first radiation portion and a terminal section of the second radiation portion are parallel, such that radiation of these two sections is coupled to enhance radiation characteristics of the antenna. Also, the folded structure helps to achieve compact size of the antenna.

Abstract: A multiple band electrically small compact planar microstrip antenna at VHF and UHF frequencies is provided that permits both a considerably abbreviated antenna length and significantly high efficiency antenna performance. The multiple band electrically small compact planar microstrip antenna advantageously positions a narrow radiating strip and a group of unequally dimensioned radiating members on a microstrip dielectric substrate that is stacked on a ground plane. The unequally dimensioned, or unlike, radiating members are separated by at least one gap and cause the antenna to resonate at a number of different frequencies instead of a single frequency as the prior art microstrip antenna. The multiple band electrically small compact planar microstrip antenna also innovatively filters unwanted signals at other frequencies because of the narrowband nature of each band.

Abstract: The invention relates in part to a folded dipole having a dipole axis and a pair of arms which together have a profile which is concave on one side and convex on the other when viewed along the dipole axis. The dipoles may be arranged as a dipole box around a central region, typically in a generally circular or square configuration. Further elements may be placed in the dipole box or in the gaps between dipole boxes. The antenna may be a single-band antenna, or a multi-band antenna with the further elements operating in a different frequency band to the dipole boxes. The further elements may be concentric dipole boxes. The invention is particularly suited for use in a cellular base station panel antenna. A novel coaxial to microstrip transition is also described.

Abstract: The present invention relates to a bent folded dipole antenna for reducing a beam width difference, which can reduce a beam width difference, varying with a frequency band, and generate dual polarization through the use of an antenna structure having a bent folded dipole antenna unit, in which a plurality of bent folded dipole components is connected to each other as a single pattern, and a feeding unit for feeding a signal to the folded dipole antenna unit. Therefore, the present invention is advantageous in that it can reduce a beam width difference varying with a frequency band, simplify the structure of the antenna to reduce the cost thereof, and easily obtain dual polarization characteristics and wide band characteristics by combining a feeding unit for feeding a signal in a dual feeding manner with the bent folded dipole antenna unit implemented as a single pattern.

Abstract: An antenna is provided which includes a primary folded dipole element and a feed for the primary folded dipole element. The primary folded dipole element is operable to resonate at a first frequency range. A parasitic dipole element is located within the primary folded dipole element and is spaced therefrom. The parasitic dipole element is operable to resonate at a frequency range that is higher than the first frequency range. Additional parasitic dipole elements may be located within the primary folded dipole element and spaced therefrom to resonate at different frequency ranges.

Abstract: The present invention relates to a tag-use antenna allowing a miniaturization while maintaining a constant minimal change of a communication distance. The tag-use antenna has a feed part of a folded dipole antenna of a size of 53 mm long and 7 mm wide being connected to, and equipped with, an LSI chip of Rc=500 ohms and Cc=1.4 pF and is covered with plastic resin 13 of the dielectric constant ?r=3 and thickness of t=0.75 mm on both sides of the antenna. The dipole part of 1 mm wire path width of the tag-use antenna is formed in a rectangular spiral by being bent inward from both ends at bending parts at four places. The entire length of the dipole antenna when extending the four bending parts straight is featured so as to be shorter than one half of a resonance wavelength of the antenna. An inductance part is featured in the intermediate part of the both dipole parts in the neighborhood of the center of the antenna.

Abstract: A transmitting and receiving system including an antenna element having first and second current paths, and a meander feed line connected to said first and second current paths, the meander feed line including a radiating portion parallel to the first current path, wherein a current in the radiating portion is in a direction opposite of a current in the first current path, and wherein a current in the second current path is in a direction the same as the current in said radiating portion.

Abstract: A conductor for use as a radiator in an antenna has a contact section adapted to connect to a high-frequency source, a first section of alternating shape extending along a first longitudinal axis from an inner end at the contact section to an outer end, and a second section of alternating shape extending along a second longitudinal axis generally coplanar with and parallel to the first axis from the first-section outer end toward the contact section. It can also have a third section of alternating shape extending along a third longitudinal axis generally coplanar with and parallel to the first and second axes from the contact section and having an outer end flanked by the first and second sections.

Abstract: An antenna and a wireless mobile communication device incorporating the antenna are provided. The antenna includes a first conductor section electrically coupled to a first feeding point, a second conductor section electrically coupled to a second feeding point, and a near-field radiation control structure adapted to control characteristics of near-field radiation generated by the antenna. Near-field radiation control structures include a parasitic element positioned adjacent the first conductor section and configured to control characteristics of near-field radiation generated by the first conductor section, and a diffuser in the second conductor section configured to diffuse near-field radiation generated by the second conductor section into a plurality of directions.

Abstract: A meander line antenna formed in the shape of meander is disclosed. The meander line antenna includes a bottom half section that is constituted by a folded conductive pattern of a folded dipole antenna, and includes a feeding point for mounting an IC chip at the central part; a top half section that is constituted by a folded conductive pattern of a folded dipole antenna shaped like the bottom half section; and a frequency adjusting section consisting of connecting conductive patterns arranged at an interval corresponding to a desired frequency centering on the feeding point, the connecting conductive patterns connecting the bottom half section and the top half section. The connecting conductive patterns can be cut off, and the folded conductive pattern outside of the cut-off connecting conductive patterns can be removed.

Abstract: A multiple-element antenna for a multi-band wireless mobile communication device is provided. The multiple-element antenna includes a first antenna element, a second antenna element positioned adjacent the first antenna element, and a parasitic coupler positioned adjacent the first antenna element and the second antenna element. In one embodiment, the first and second antenna elements have respective first and second operating frequency bands, and electromagnetically couple with each other and with the parasitic coupler when the multiple-element antenna is operating in the first or second operating frequency band. The first and second antenna elements are configured to be connected to first and second transceivers in a wireless mobile communication device in an alternate embodiment.

Abstract: In a UHF broadband antenna, a pair of dipole elements are provided. Each of the dipole elements is shaped into a rectangular plate.

Abstract: An omnidirectional resonant antenna in a half-plane or in the whole plane comprises a single radiating electric conductor (26) having at least three abutted wires (28, 30, 32), the length of each wire and the orientation of the wires relative to one another determining the global orientation of the electric conductor. The wires are oriented along at least three different spatial directions and the lengths of the wires are designed to obtain an omnidirectional global radiation of the electric conductor in a half-plane or in the whole plane.

Abstract: A miniature broadband monopole antenna design configured with integrated band-selecting filtering is disclosed. The antenna is electrically folded, and includes top and bottom monopole sections, with a meanderline to provide an inductive load between the two sections. The overall antenna structure can be embedded in a relatively small, RF transparent, composite structure (e.g., such as the fin of a guided munition), and has minimal impact on aerodynamics (low drag). The top, bottom, and meanderline elements of the antenna operate together to collectively provide multi-band operation (e.g., 30 MHz to 3 GHz).

Abstract: A printed dipole antenna comprises bent dipole arms connected to respective feed lines formed on opposed surfaces of a substrate. In one particular embodiment, the dipole antenna is provided as a folded dipole, including two or more connector lines to provide an increased frequency range. Two of these dipole antennae may advantageously be combined to an antenna system having a superior radiation characteristic in that the two dipole antennae are arranged to have a different orientation. A corresponding circuitry may then select the antenna, which provides superior operation at a given time.

Abstract: A low profile antenna having relatively high radiation resistance, wide bandwidth and which utilizes a single conductor and RF source is disclosed. In accordance with an exemplary embodiment, the upper horizontal portion and the lower horizontal portion of the double inverted-L antenna are respectively brought down and up (without being physically connected) at a distance of approximately 180 degrees (½?) from the RF source so as to form two additional vertical portions of the antenna. This is followed by two approximately 90-degree (¼?) horizontal conductors portion. The resulting radiation resistance of the low profile antenna is approximately three-times that of a double inverted-L antenna.

Abstract: An antenna includes a first dipole having first and second stripline radiating elements extending in opposite directions from a central feed point and along a generally rectangular outline of the antenna. The first dipole is operable to be resonant at a first frequency. The antenna also includes a second dipole having third and fourth stripline radiating elements extending in opposite directions from the central feed point and generally parallel to the first and second stripline radiating elements. The third and fourth stripline radiating elements generally follow and stay within the rectangular antenna outline. The second dipole is operable to be resonant at a second frequency. The antenna also includes a stripline balun electrically coupled to the central feed point and extending generally parallel with the first and second dipoles and along the rectangular antenna outline.

Abstract: The invention concerns a patch antenna (20) for a small-sized portable electronic instrument comprising a radiating element (21) separated from a ground plane (23) by a dielectric (22) and comprising feed (25) and ground (26) conductors for electrically connecting said radiating element and said ground plane (23) respectively, to an electric module (6). The ground plane (23) consists of a stamped metal plate including at least a folded foot (26a, 26b) outside said ground plane and directly connecting said ground plane (23) to said electronic module (6), said foot (26a, 26b) forming said ground conductor (26) of the antenna.

Abstract: An antenna apparatus for a folder type mobile phone, wherein a first antenna is installed in a main body of the folder type mobile phone, and a second antenna is installed in the folder. The folder type mobile phone installs a main antenna apparatus in the main body, and an antenna apparatus for maximizing the diversity effect in the folder. As a result, it becomes more convenient to carry the folder type mobile phone based on the diversity mode, while securing a broader separation distance between two antennas at the same time.

Abstract: A multiple-element antenna for a multi-band wireless mobile communication device is provided. The multiple-element antenna includes a first antenna element, a second antenna element positioned adjacent the first antenna element, and a parasitic coupler positioned adjacent the first antenna element and the second antenna element. In one embodiment, the first and second antenna elements have respective first and second operating frequency bands, and electromagnetically couple with each other and with the parasitic coupler when the multiple-element antenna is operating in the first or second operating frequency band. The first and second antenna elements are configured to be connected to first and second transceivers in a wireless mobile communication device in an alternate embodiment.

Abstract: A shaped antenna element that radically reduces the physical size needed for resonance without the use of lossy loading elements, while at the same time allowing direct connection to a coaxial feeder. The element is composed of at least two sub-elements in close proximity to each other, coupled electrically to each other such that the radiation resistance of the composite element is increased substantially. The composite element can be used either as an antenna or part of an antenna that consists of multiple such elements in order to provide increased directivity.

Abstract: A multi-frequency antenna with a single layer and a single feeding point, and especially an improved microstrip antenna with its bandwidths simplified and enlarged, it has a central microstrip with a set length and a set width; the bottom end of the central microstrip is used as a feeding point, the top end thereof is extended bilaterally to form respectively a first band section and a second ban section. The first band section is provided on the end thereof with a first open circuit point, and the second ban section is provided on the end thereof with a second open circuit point. A grounding line of a set length and a set width is located at a position a distance below the feeding point on the bottom end of the central microstrip. The lengths from the feeding point to an open circuit point on the end of the first band section and to an open circuit point on the end of the second ban section are both ¼ ? of the ban section to be used.