MXPA01006012A - Printed multi-band patch antenna - Google Patents

Abstract

The present invention provides a miniature, built-in multi-band antenna which is suitable for use in future compact mobile terminals. According to exemplary embodiments, a built-in patch antenna is provided which includes patch elements of different sizes and capable of being tuned to different frequency bands. On each patch element is formed a slot which divides the patch element into sub-parts. Each sub-part of a patch element is structured so as to be resonant at a frequency in the same frequency band to which the patch element is tuned. As a result, a high efficiency, broad band, multi-band, and surface mountable low profile antenna can be realized.

Description

PRINTED CONNECTION ANTENNA OF MULTIPLE BANDS RELATED APPLICATIONS This application is related to United States Patent Application No. 09 / 112,366 assigned to Ying, filed on July 9, 1998, and entitled "Miniature Printed Spiral Antenna for Mobile Terminates" (Printed spiral type miniature antenna for Mobile Terminals) and United States Patent Application No. 09 / 112,152, assigned to Ying on July 9, 1998, entitled "Twin Spiral Dual Band Antenna" (Dual Spiral Antenna Double Band). BACKGROUND OF THE INVENTION The present invention relates generally to radiocommunication systems and, in particular, to integrated antennas which can be incorporated into portable terminals and which allow portable terminals to communicate within different frequency bands. The cell phone industry has made great strides in commercial operations in the United States as well as in the rest of the world. Growth in major metropolitan areas has exceeded expectations and is rapidly outstripping system capacity. If the trend continues, the effects of the growth of this industry will quickly reach even the smallest markets. Innovative solutions are required to meet these growth needs as well as to maintain a high quality service and avoid price increases. In the world, an important step in the advancement of radiocommunication systems is the change of analogue to digital transmissions. Similarly significant is the selection of an effective digital transmission scheme for the implementation of next generation technology, for example, time division multiple access (TDMA) or code division multiple access (CDMA). Additionally, it is widely believed that the first generation of Personal Communication Networks (PCN), which employ inexpensive pocket-sized cordless phones that can be comfortably ported and used to make or receive calls in the office, street, car, etc., they will be provided, for example, by cell phone companies that use the next-generation digital cellular system infrastructure. To provide an acceptable level of equipment compatibility, standards have been created in various regions of the world. For example, analog standards such as AMPS (Advanced Mobile Phone System), NMT (Mobile Phone Nordic) and ETACS and digital standards such as D-AMPS (for example, as specified in EIA / TIA-IS-54-B and IS-136) and GSM (Global System for Mobile Communications adopted by ETSI) have been promulgated to standardize design criteria for radiocommunication systems. Once created, these standards tend to be reused equally or similarly, to specify additional systems. For example, in addition to the original GSM system, there is also the DCS1800 (specified by ETSI) and PCS1900 (specified by JTC in J-STD-007), both based on GSM. However, the most recent evolution in cellular communication services involves the adoption of additional frequency bands for use in the handling of mobile communications, for example, for Personal Communication Services (PCS services). Taking the United States as an example, the cellular hyperband has assigned two frequency bands (commonly known as frequency band A and frequency band B) to carry and control communications in the 800 MHz region. The PCS hyperband, on the other hand On the other hand, it is specified in the United States to include six different frequency bands (A, B, C, D, E, and F) in the 1900 MHz region. Therefore, eight frequency bands are available today in any service area in the United States to facilitate communication services. Certain standards have been approved for the PCB hyperband (for example, PCS1900 (J-STD-007)), while others have been approved for the cellular hyperband (for example, D-AMPS IS-136)). Each of the frequency bands for the cellular and PCS hyperbanks is assigned a plurality of traffic channels and at least one access or control channel. The control channel is used to control or supervise the operation of mobile stations by means of information transmitted to or received from mobile stations. Such information may include arrival signals, exit signals, search signals, search response signals, location registration signals, voice channel assignment, maintenance instructions, delivery, and selection of cells or reselection instructions when moving a mobile station outside the range of radio coverage of one cell to the radio coverage of another cell. The control and voice channels can operate using analog modulation or digital modulation. The signals transmitted by a base station in the downlink on the traffic and control channels are received by mobile or portable terminals, each of which have at least one antenna. Historically, mobile terminals have used a different number of antenna types to receive and transmit signals over the air interface. For example, it has been found that mono-polar antennas mounted perpendicular to a conductive surface provide good radiation characteristics, desirable impulse point impedances and relatively simple construction. Mono-polar antennas can be created in various physical forms. For example, rod or pole antennas have been used frequently in conjunction with portable terminals. For high frequency applications where the length of the antenna should be minimized, another selection is the helical antenna. As described above, it will soon be commercially desirable to offer terminals which are capable of operating in different frequency bands, for example, bands located in the 900 MHz region and in bands located in the 1800 MHz region. Accordingly, the antennas that provide adequate gain and bandwidth in both frequency bands will require to be employed in portable terminals in the near future. Several attempts have been made to create such double band antennas. For example, U.S. Patent 4,571,595 to Phillips et al. Describes a double band antenna that has a sawtooth-shaped element. The dual band antenna can be tuned to any of two nearby frequency bands (for example, centered at 915 MHz and 960 MHz). This antenna design is, however, relatively inefficient since it is physically close to the mobile phone frame.

Japanese Patent 6-37531 discloses a spiral which contains an internal parasitic metal bar. In this patent, the antenna can be tuned to double resonant frequencies by adjusting the position of the metal bar. Unfortunately, the bandwidth for this design is too narrow for use in cellular communications. Mono-polar antennas, double-band printed, are known in which double resonance is obtained by the addition of a parasitic strip next to a printed mono-polar antenna. While said antenna has enough bandwidth for cellular communications, it requires the addition of a parasitic strip. Montecco AB in Sweden has designed a compatible twin-band antenna and a coil antenna, in which double resonance is obtained by adjusting the coil connection component (1/4? For 900 MHz and 1/2? For 1800 MHz). This antenna has relatively good bandwidth and radiation operation and a length in the order of 40 mm. A non-uniform helical double band antenna which is relatively small in size is disclosed in the United States Patent Application. commonly assigned No. 08 / 725,507, entitled "Non-Uniform Helical Antennae of Multiple Band".

DE-A-1970535 discloses a sheet antenna having numerous wire segments of several links connected at one end to the conductive strip. The different strips of wire have a straight shape. A central wire segment is connected at its other end to a second metal strip. The second metal strip is connected to a conductive layer of the frame that lies below the wire segments and the strips. A signal waveguide is coupled to the central wire segment and connected to the conductive layer of the frame. The wire segments help in tuning the antenna while also receiving signals. At present, antennas for radio communication devices, such as mobile phones, are mounted directly on the telephone frame. However, since the weight and size of the mobile terminals continue to decrease, the antennas described above become less advantageous due to their size. Additionally, as the functionality of these future mobile terminals increases, the need arises for an integrated antenna which is capable of resonating in multiple frequency bands. The conventional integrated antennas currently in use in mobile phones include low profile micro-strip antennas of inverse F. The micro strip antennas are of small dimension and low weight. The low-profile reverse F antenna (PIFA) has already been implemented in portable mobile phone equipment, as described by K. Qassi, "F-Reverse Antenna for Portable Handheld Equipment", IEE Colloquium on Microwave Filters and Antennas for Personal Communication Systems ", pages 3/1 - 3/6, February 1994, London, United Kingdom, and more recently, Lai et al., Has published a reverse F mobile antenna (WO 96/27219). it has a size which is about 40% of the conventional PIFA antenna, FIGURES 1A and IB illustrate a conventional low-profile antenna compared to the reverse F winding antenna described in Lai et al. The conventional low-profile antenna of the FIGURE 1A has both the size and length equal to, for example, a quarter of the wavelength of the frequency at which the antenna must be resonant.The serpentine antenna of inverse F, illustrated in FIGURE IB, also has a length equal to one quarter of the length waveform of the resonant frequency and a width equal to W; however, the size of the reverse F mobile antenna is reduced by 40% of the size of the conventional low-profile antenna. The reduction in size is attributable to the serpentine shape of the antenna. However, as mobile phones become smaller and smaller, both micro-strip and PIFA antennas are still too large to be installed in the frame of future phones. In commonly assigned co-pending patent application No. 09/112, 366, entitled "Printed Miniature Spiral Antenna for Mobile Terminals", is proposed an inter-antenna built in spiral printed with terminal coupling. The size of the antenna was reduced between 20% and 30% compared to the conventional PIFA antenna (less than 1/10 of the wavelength) making it suitable for future mobile phones. In addition to a small antenna size, next generation mobile phones will require the ability to tune to more than one frequency band, for cellular wireless local area network, GPS and diversity. In the commonly assigned co-pending Patent Application No. 09 / 112,152, entitled "Double Double Spiral Band Antenna", an integrated multi-band antenna was proposed which is suitable for future mobile telephones. The integrated antenna comprises two spiral conductor arms which are of different lengths and are capable of being tuned in different frequency bands. In order to increase the bandwidth of the antenna, a load resistance technique is introduced. There is a need for an efficient miniature integrated antenna which is capable of tuning to different frequency bands while simultaneously having a wide bandwidth in each of those multiple frequency bands. SUMMARY OF THE INVENTION The present invention overcomes the shortcomings identified above in the art by providing a miniature integrated multiple band connection antenna which is suitable for use in future compact mobile terminals. According to example modalities, a connection bridge and connecting elements of different sizes capable of being tuned to different frequency bands. A slot is formed in each connection element which divides the connection element into sub-parts. Each sub-part of the connecting element is structured to be resonant at a frequency in the same frequency band to which the connecting element is tuned. As a result, a low-profile, wide-band, high-efficiency, low profile, surface-installable antenna can be implemented. BRIEF DESCRIPTION OF THE DRAWINGS The objects and features above of the present invention will be more apparent in the following description of the preferred embodiments with reference to the accompanying drawings, wherein: FIGS. 1A and IB illustrate the conventional low-profile antenna compared to the conventional inverted serpentine antenna F; FIGURE 2 illustrates a conventional radio communication device in which the antenna of the present invention can be implemented; FIGURE 3 illustrates a multi-band antenna integrated in accordance with the present invention; FIGURE 4 illustrates an example antenna configuration in which each connection part is formed of three sub-parts; FIGURES 5A and 5B illustrate the process of forming a broadband multiple band antenna according to the present invention; FIGURE 6A illustrates a top view of a two-part dual band connection antenna according to cor. a first example embodiment of the present invention; FIGURE 6B illustrates a two part L slot antenna according to a second exemplary embodiment of the present invention; FIGURE 6C illustrates a two part L slot antenna according to a third example embodiment of the present invention, in which the connection is arbitrary; FIGURE 6D a two-part slot L antenna according to a fourth exemplary embodiment of the present invention, in which both the connection and the slots are arbitrarily; FIGURE 7 provides a graph which illustrates the bandwidth which can be obtained from the sub-parts of the largest connection in FIGURE 6B; and FIGURE 8 illustrates a simulation result of a GSM / DCS dual band antenna of the present invention. DETAILED DESCRIPTION FIGURE 2 illustrates an exemplary radio communication device 200 in which the integrated multiple band connection antenna of the present invention can be implemented. The communication device 200 includes a frame 210 having an aperture for microphone 220 and an aperture for microphone 230 located approximately adjacent to the position of the mouth and ear, respectively, of a user. A keyboard 240 allows the user to interact with the communication device, for example, by entering a telephone number to be dialed. The communication device 200 also includes an integrated connection antenna assembly 250, details of which will be described below. FIGURE 3 illustrates an example integrated connection antenna assembly according to the present invention. The exemplary integrated connection antenna assembly according to the present invention comprises two connection parts 305 and 310, each having a different size. The two connection parts 305 and 310 are fixed to a printed circuit board (PCB) 315 by means of a dielectric substrate 320 and are connected to opposite sides of a coupling bridge 330. A slot 340 is formed in each part 305 and 310 which divides the connecting parties into sub-parts, the importance of which is discussed in detail below. The connecting parts 305 and 310 are placed on the PCB 315 and form slots between the connecting parts and the PCB 315. Those skilled in the art will appreciate that the connecting parts form the main radiators (or sensors) of the antenna system of the present invention. As evident in FIGURE 3, the connecting parts 305 and 310 are powered by the feed pin 325. The integrated antenna also includes a coupling bridge 330 positioned between the feed pin 325 and the ground post 335. The bridge coupling 330 acts to tune the antenna and forms a small gauze antenna between the feed pin 325 and the ground post 335. The tuning of an antenna refers to coupling the impedance seen by the antenna at its input terminals so that the input impedance is seen as only resistive, this being, it will not have an appreciable reactive component. The tuning of the antenna system of the present invention is carried out by measuring or estimating the input impedance associated with an antenna providing a corresponding circuit of appropriate impedance (this being, a corresponding bridge). The correspondence of the antenna, according to the present invention, can be adjusted by changing the length of the correspondence bridge 330. This is carried out simply by changing the location of the ground post 335. The length of the correspondence bridge is generally in the order between 0.01? to 0.1? It is evident from FIGURE 3 that the two connection parts 305 and 310 of the antenna system are of different sizes. By controlling the size of the connection parts, the antenna is capable of being tuned to different frequencies. The first connection part 305 of the multi-band antenna is of a size (generally one quarter of the wavelength of the frequency band to which the connection must be tuned) to be resonant at the frequencies in a first low band, and the second connection part 310 is of a size to be resonant at the frequencies in a second high band. The two connection parts can be resonant at any frequency. For example, the first band may be a GSM band and the second band may be a DCS band. For example, other possible combinations of high and low bands may include GSM + PCS, GSM + WCDMA, DCS + WCDMA, GSM + GPS, GSM + ISM, or any other combination of high and low frequency bands. As indicated above, each connection part 305 and 310 includes a slot 340 which acts to separate the connection parts into sub-parts. Each sub-part of a connection part is resonant at a different frequency within the same frequency band to which the connection part is tuned. For example, the first connection part 305 is of a size to be resonant at frequencies in the GSM band, then the sub-parts of the connection part 305 may be resonant at different frequencies within the GSM band. As a result, a greater bandwidth can be obtained. A person skilled in the art may appreciate that, alternatively, three or more parts may be formed in each connection part. FIGURE 4 illustrates an example configuration in which each connection part is formed of three sub-parts. As illustrated, the first connection part 405 is cut into three sub-parts 405A-405C and the second connection part 410 is also cut into three sub-parts 410a-410C. Each of the sub-parts may be resonant at a different frequency within the same frequency at which the respective connection parts are resonant. As such, a wider bandwidth can be obtained with such configuration, however, tuning is more difficult. Returning to FIGURE 3, the connecting parts 305 and 310 can have any shape, including in three dimensions. The size of the connecting parts, however, should be approximately one quarter of the wavelength of the frequency at which the connecting parts will be tuned. The resonant frequencies and the bandwidth of the integrated multiple band connection antenna of the present invention depend on the area and thickness of the dielectric substrate, the type of dielectric material selected (being this the dielectric constant), the size of the connection and the size and location of the slots. Those skilled in the art will appreciate that an increase in the area and thickness of the dielectric substrate or connection size or a decrease in the value of the dielectric constant results in an increase in the bandwidth which can be obtained. In addition, the bandwidth also depends on the size and location of the slots formed in the connection parts. As is evident in FIGURE 3, the integrated multiple band connection antenna of the present invention can be mounted on the edge of the PCB which provides better radiation efficiency and bandwidth. In addition, the space requirement of the PCB for the integrated multiple band connection antenna is decreased due to its smaller size. FIGURES 5A and 5B illustrate a technique by which the broadband multiple band connection antenna, of the present invention is formed. The broadband multiple band connection antenna of the present invention can be formed from a conventional connection antenna by forming a slot in the conventional connection antenna, as illustrated in FIGURE 1A along a bridge axis of coupling so that two connection parts are created, connected to opposite sides of the coupling bridge (see FIGURE 5A). Each part has a size to be resonant at a different frequency. The larger part 505 is resonant at a lower frequency and the larger part 510 is resonant at a higher frequency. The shaping of the groove can be done by any of the following methods: "* cutting, engraving, MID (3D metallization) or chemical processing.A groove is formed in each part to divide each part into sub-parts (see FIGURE 5B The slots can be arbitrarily; however, the shape of the slot affects the achievable bandwidth. As indicated above, each sub-part of the connection part is resonant at a different frequency within the same frequency band to which the connection part is tuned thereby increasing the bandwidth of the antenna. FIGURES 6A-6D illustrate designs of connection antennas. FIGURE 6A illustrates a top view of a two-part dual band connecting antenna according to a first exemplary embodiment of the present invention. The dotted line passing through the feed bolt 325 and the ground pin 335 divides the connection into left and right portions 505 and 610, respectively. The right part 605, which is larger, is a low frequency resonator and the left part 610 is a high frequency resonator. As evident in FIGURE 6A, the slot is formed in each of the connecting portions to produce a double spiral configuration, similar to that presented in Patent Application No. 09 / 112,152. In this case, however, the spiral strip line is actually a spiral connection, resulting in improved bandwidth. FIGURE 6B illustrates a two-part slot connection antenna L according to a second embodiment of the present invention. As illustrated, face connection portions 615 and 620 are rectangular in shape. As in FIGURE 6A, the dotted line separates the connection into right and left portions 615 and 620, respectively. The right part 615 is a low frequency resonator and the left part 620 is a high frequency resonator. A slot of form L is formed in each of the parts. These slots divide the parties into two sub-parts. Similarly, the left part 620 is divided into sub-parts 620A and 620B. As indicated above, each sub-part of a connection part is resonant at a different frequency in the same frequency band to which the connection is tuned. Four sub-parts 615A and 615B, for example, the outer sub-part 615A is resonant at a lower frequency (ft) and the inner part 615B is resonant at a higher frequency (f?). As a result, a broad bandwidth is obtained within the same frequency band. FIGURE 7 illustrates the multi-resonance capability of the connection parts, in accordance with this embodiment of the present invention. As shown, a broad bandwidth coupling is performed. FIGURES 6C and 6D illustrate example configurations in which, in FIGURE 6C, the parts have L-shaped grooves and are arbitrarily formed, and in FIGURE 6D, both connecting portions and grooves have arbitrary shapes. Similar to FIGURES 6A and 6B, the dotted line in FIGURES 6C and 6D divides the connection into two parts. A connecting part in each of FIGS. 6C and 6D is smaller in size (630 and 640 being in FIGS. 6C and 6D, respectively) and, therefore, a high frequency resonator while the connecting part it is larger (this being, 625 and 635 in FIGURES 6C and 6D, respectively) and, therefore, a low frequency resonator. The slots of each of the connection parts divide the connection parts into two sub-parts, each of which is resonant at a different frequency in the same frequency band to which the respective connection is tuned. In FIGURE 6C, for example, the larger connecting part 625 is divided into two sub-parts 625A and 625B and the smaller connecting part 630 is divided into sub-parts 630A and 630B. Similarly in FIGURE 6D, the largest part 635 is divided into two subparts 635A and 635B and the smaller part 64 is divided into subparts 640A and 640B. As a result, broad bandwidth coupling can be carried out by means of the configurations in FIGS. 6C and 6D. In order to illustrate the effectiveness of the present invention, FIGURE 8 presents results of a simulation for the example dual band connection antenna illustrated in FIGURE 4B. The dual band connection antenna has a length of 0.1 of the wavelength, a width of 0.12 of the wavelength and a height of 0.02 of the wavelength. The parts of the connection are resonant to the GSM and DCS frequency bands. The bandwidth is 8.7% (this being about 80 MHz) in the GSM band and 9.4% (this being close to 170 MHz) in the DCS frequency band for a VSWR less than 2.5: 1. FIGURE 5 illustrates the VSWR operation of this design. As is evident in FIGURE 5, this antenna can satisfy the requirements of a dual band GSM / DCS application. The foregoing has described the principles, preferred embodiments and modes of operation of the present invention. However, the present invention should not be construed as limited to the particular embodiments discussed above. For example, while the antenna of the present invention has been discussed primarily as radiation, those skilled in the art will appreciate that the dual band connection antenna of the present invention could also be used as a sensor to receive information at specific frequencies. .

Claims (1)

1. CLAIMS A communication device for use in a radio communication system, said device is characterized in that it comprises: an opening for a microphone to allow the communication device to receive auditory information from a user; a speaker opening to allow the communication device to receive auditory information from said user; a keyboard; and an integrated multiband connection antenna comprising: a feed pin (325), a ground pin (335), a coupling bridge (330) positioned between the feed pin and the ground pin for tuning the antenna , a first connection part (305) tuned to a first frequency band, a second connection part (310) tuned to a second band of a different frequency, and at least one slot (340) formed in each of the first and second connection parts. The communication device of Claim 1 is characterized in that said first frequency band is a low frequency band and said second frequency band is a high frequency band. The communication device of Claim 1 is characterized in that said connection parts are of arbitrary three-dimensional shape. The communication device of Claim 1 is characterized in that said connection parts are of arbitrary two-dimensional shape. The communication device of Claim 1 is characterized in that said coupling bridge is used to couple an input impedance of said antenna. The communication device of Claim 5 is characterized in that the coupling of said antenna is adjusted by changing the length of the coupling bridge. The communication device of Claim 1 is characterized in that at least one of said slot divides each connection part into sub-parts. The communication device of Claim 7 is characterized in that each sub-part of the respective connection part is resonant at a different frequency within the frequency band to which the respective connection part must be tuned. The communication device of Claim 1 is characterized in that at least one slot in each of said connecting portions is suitably shaped to form said connecting portions in a double spiral configuration. The communication device of Claim 1 is characterized in that the frequency band to which each part is tuned depends on the size of the connection part. The communication device of Claim 1 is further characterized in that it has: a printed circuit board; and a substrate in which said integrated multi-band antenna is mounted, said substrate is mounted on said printed circuit board. The communication device of Claim 1 is characterized in that the size of the connection parts is selected to be approximately the wavelength of the different frequency bands to which the connection parts will be tuned. The communication device of Claim 1 is characterized in that a bandwidth of said antenna depends on the size of said connecting portions, a shape and location of said at least one slot, and the thickness and dielectric constant of said substrate. The communication device of Claim 1 is characterized in that the shape of said slot is arbitrary. An antenna for a communication device, said antenna is characterized in that it contains: a plurality of connection parts (305, 310), each of which is tuned to a frequency band; and at least one slot (340) formed in each of said plurality of connection parts for dividing the connection parts into sub-parts, each sub-part of a connection part being resonant at a different frequency within the frequency band to which the connection part is tuned, wherein said antenna is an integrated antenna. The antenna of Claim 15 is characterized in that a first connection part is resonant at frequencies in a low frequency band and a second connection part is resonant at frequencies in a high frequency band. The antenna of Claim 16 is characterized in that the size of said first connection part is larger than the size of said second connection part. The antenna of Claim 15 is characterized in that said connection parts are connected to a printed circuit board of said radio communication device through the substrate. The antenna of Claim 18 is characterized in that a bandwidth of said antenna depends on the size of said connecting portions, a shape and location of at least one slot, and a thickness and dielectric constant of said substrate. The antenna of Claim 15 is characterized in that the shapes of said connecting portions and said at least one slot are arbitrary. A method of forming a multiple band connection antenna comprising a connection and a coupling bridge, said method is characterized in that it has the step of: forming a slot (340) in said connection so that said connection is divided into several connected parts only in said coupling bridge (330), each of said plurality of parts is of a suitable size in order to be resonant at a different frequency. The method of Claim 21 is further characterized in that it has the step of: forming at least one slot in each connection part to divide each connection part into a plurality of sub-parts, each sub-part of the connection part is resonant at a different frequency within the frequency band to which the connection part must be tuned. The method of Claim 22 is characterized in that said forming steps are effected through cutting, etching, chemical or metallizing process.