Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
  • H04B1/3827—Portable transceivers
  • H04B1/3833—Hand-held transceivers
  • H04B1/3838—Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/08—Means for collapsing antennas or parts thereof
  • H01Q1/084—Pivotable antennas
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
  • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
  • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
  • H01Q1/242—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use
  • H01Q1/243—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use with built-in antennas
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
  • H01Q3/24—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Definitions

• This invention relates to antennas and, more particularly, to antenna placement in a cellular phone.
• Antennas are generally used for transmission and reception of electromagnetic waves.
• An antenna operates by converting electrical current to (transmission) and from (reception) electromagnetic waves.
• One measure of antenna performance is "gain".
• Gain is based on the directivity and efficiency of the antenna.
• Directivity is an antenna's ability to focus energy in a desired direction. If desired, energy can be focused into a narrow beamwidth. This focused energy gives the ability to communicate over great distances, but as the angle of the antenna changes, the direction of the beam also changes, thus requiring proper orientation of the antenna for a good signal.
• Efficiency of an antenna concerns the amount of dissipative loss associated with the reception of a particular signal.
• Antennas can be designed in many different ways depending on their intended use.
• an antenna In cellular communications, for example, an antenna is designed for maximal "gain" at a particular frequency. Such a design is conventionally accomplished by constructing an antenna that is a fraction of the wavelength of the desired operating frequency.
• the antennas used in mobile stations for cellular communications are generally small, both electrically and physically. The size of the antenna is generally a function of the communication device itself, which is usually worn on the body or held in the hand of the user.
• Internal antennas for mobile stations offer an advantageous form factor that is convenient for slipping the device in a pocket or purse.
• External antennas increase the length of a mobile station and often snag when the device is being removed from, or returned to, a pocket or purse.
• reception and transmission may be hindered by various factors.
• One hindrance of particular concern in cellular communications is interference by a mobile station user's body. Such interference usually occurs due to placement of the user's head or hands between the mobile station and a base station.
• Body effect occurs because the human body conducts electromagnetic waves away from the mobile station's transceiver. In the case of cellular telephones, this effect is intensified because of the user's close proximity to the mobile station antenna. For example, it is common to see a mobile station user covering part of the antenna with his hand when using the telephone. When the user grips the mobile station, the hand effectively becomes part of the ground plane of the antenna. The resulting change in size of the ground plane can adversely affect the performance characteristics of the antenna. Effects on the antenna can include, for example, frequency response shifts and decreased efficiency (including significant loss of signal).
• the user can cause a drop cause a drop in gain of 5 to 20 dB or more by covering the antenna with his hand
• a microstrip, or "patch,” antenna consists of a square of dielectric material, for example, ceramic, plated with a smaller area of metal. Patch antennas require a ground plane. In theory, the ideal ground plane for a patch antenna is of infinite size. Practically, the ground plane should be significantly larger than the patch itself. Performance of the antenna is directly correlated to the size of the antenna and relative size of ground plane.
• Figure 1 depicts an example of a microstrip antenna.
• the antenna comprises a patch antenna surface 102 and a ground plane surface 104 roughly the same size as the antenna surface.
• a dielectric material 106 is arranged between the patch and the ground plane.
• microstrip antennas are known for their advantages in terms of light weight, flat profiles, low manufacturing cost, and compatibility with integrated circuits.
• the most commonly used microstrip antennas are the conventional half-wavelength and quarter- wavelength rectangular patch antennas.
• Other microstrip antenna configurations have been studied and reported in the literature, such as circular patches, triangular patches, ring microstrip antennas, and the above-mentioned C-patch antennas.
• a high performance built-in antenna is required to have a very small size, a compact structure, a wide bandwidth, a quasi-isotropic radiation pattern, and to exhibit a negligible susceptibility to the proximity of the human body.
• the microstrip antenna is one of the most preferable antenna types for small, portable wireless communication devices, particularly when a built-in antenna is required. Since the microstrip antenna can be made with a very thin and compact structure, it can easily match various types of wireless units.
• an electrically symmetrical microstrip antenna is positioned internal to the body of the wireless device.
• the antenna is connected to the transceiver at one of the electrically symmetrical ends.
• the antenna is connected to the transceiver at the other electrically symmetrical end. Shifting the connection point of the antenna allows the antenna to be relocated to a position that is less likely to be subject to adverse effects caused by body proximity.
• two microstrip antennas are positioned at opposite ends, and internal to, the casing of the wireless device.
• An antenna switch is used to control which antenna is connected to the transceiver unit at any given time. When the device is closed, the switch connects the antenna with the better signal (usually the antenna closest to the transceiver) to the transceiver. When the device is opened, the switch connects the antenna least affected by user interference to the transceiver unit.
• the disclosed embodiments provide several advantages. For example, improved antenna gain is achieved due to dynamic location of an internal antenna. The amount of signal loss due to the mobile station user's body being in proximity to the wireless device is reduced. Reliability of communications is improved due to the ability of the mobile station to connect to an antenna with better gain. Signal loss due to the mobile station user's fingers resting on an external antenna is eliminated. Compliance with FCC specific absorption ratio (SAR) regulations is more easily accomplished. Finally, the mobile station and its user are protected from antenna damage due to snagging of an external antenna.
• SAR FCC specific absorption ratio
• Figure 1 depicts an example of a prior art microstrip antenna.
• Figures 2A and 2B depict a mobile station with a slide-type cellular phone casing having an internal electrically symmetrical microstrip antenna.
• Figure 3 depicts a slide-type cellular phone casing for a mobile station with more than one internal antenna.
• Figure 4 depicts a mobile station with a slide-type cellular phone casing having an internal electrically symmetrical microstrip antenna.
• Figure 5 depicts a block diagram of a mobile station that can make use of the disclosed embodiments.
• Figures 2A and 2B depict a mobile station with a movable-type cellular phone casing 202 which includes an internal electrically symmetrical microstrip antenna.
• a movable-type casing is typified in that a moveable portion of the case 206 must be moved for the user to access some functions of the device.
• the casing 202 is a slide-type casing.
• device functions are generally accessed through the numeric keypad and other control keys 216. These keys 216 are positioned in the stationary portion of the case 204.
• the movable portion of the case 206 typically contains a microphone. Moving the movable portion of the case 206 to the open position generally moves the microphone to a position that offers better pickup of the user's voice.
• Figure 2A depicts a mobile station with a slide-type cellular phone casing 202 which is closed.
• the movable portion of the casing 206 covers the keyboard 216 when the casing 202 is closed.
• Most device functions are not user-accessible while the casing is closed.
• the mobile station may be on or off.
• the mobile station When turned on, the mobile station is registered on a wireless network, if available, and searching for pages or other information.
• the mobile station is considered in stand-by mode when it is closed and on. When in stand-by mode, the user cannot initiate communications.
• the antenna 208 of the mobile station is located internal to the casing 202, in its movable portion 206.
• An electrically symmetrical microstrip (or stripline) antenna is used in the presently preferred embodiment.
• An electrically symmetrical microstrip antenna has more than one tap (or contact) point available that will yield the same antenna load and characteristics to a connected transceiver unit 218. That is, changing tap points between electrically symmetrical tap points does not change the mode (or frequency) in which the mobile station operates. However, the physical shape of such an antenna is not necessarily symmetrical.
• the tap points of the antenna 210 and 212 are at upper and lower ends of the antenna 208, with respect to the cellular casing 202.
• the antenna 208 is connected to the transceiver unit 218 at the lower tap point 210.
• the connection to the transceiver unit 218 can be accomplished by an antenna connector 214 fixed to the stationary portion of the case 204.
• Figure 2B depicts the slide-type cellular phone casing 202 of the mobile station open and ready for user interface.
• the keyboard 216 is exposed by the movable portion of the case 206 being slid downward relative to the stationary portion of the cellular casing 204.
• opening the cellular casing moves the antenna 208, which is internal to the movable portion of the case 206, downward relative to the antenna connector 214.
• the movement of the antenna 208, which is fixed in the movable portion of the casing 206, relative to the antenna connector 214, which is fixed in the stationary portion of the casing, causes the tap point of the antenna 208 to change.
• Moving the antenna downward changes the antenna connection to the transceiver unit 218 from the lower tap point 210 to the upper tap point 212.
• the movement of the antenna 208 relative to the stationary portion of the case 204 shifts it farther away from the stationary portion of the casing 204. Since this movement occurs when the casing 202 is open and therefore more likely to be affected by user interference, the amount of signal loss is reduced.
• Figure 3 depicts a mobile station with a slide-type cellular phone casing having more than one internal antenna according to an alternative embodiment.
• the casing 202, with stationary 204 and movable 206 portions, and a user interface keyboard 216 operate as described in Figures 2A and 2B.
• the cellular casing of Figure 3 is configured with two internal antennas, a lower antenna 302 which is located in the movable portion 206 of the casing 202 and an upper antenna 308, which is located in the top of the stationary portion 204 of the casing 202.
• Each antenna is connected to an antenna switch 306 located in the stationary portion 204 of the casing 202.
• the lower antenna 302 is connected (hardwired) at a single tap point 304.
• the connection of the lower antenna 302 to the antenna switch 306 should be of a material with enough length to allow the movable portion 204 of the cellular casing 202 to open without breaking or significantly stressing the antenna connection 304.
• the connection material should also be flexible enough to withstand the repeated opening and closing of the movable portion 204 of the casing 202.
• the upper antenna 308 is also hardwired to the antenna switch at a single tap point.
• the antenna switch 306 controls which antenna is connected to the transceiver unit 218.
• the antenna switch 306 can be mechanically (or electrically) operated. Sliding the casing 202 open would operate (or trigger the operation of) the antenna switch, changing the antenna connected to the receiver from the upper antenna 308 to the lower antenna 302. Switching to the lower antenna when the case is open shifts the transceiver unit 218 functions of transmitting and receiving farther away from the stationary portion of the casing. Since this switching occurs when the casing 202 is open and therefore more likely to be affected by user interference, the amount of signal loss is reduced.
• Figure 4 depicts a mobile station with a slide-type cellular phone casing having an internal microstrip antenna according to an alternative embodiment.
• the transceiver unit 218 can be connected (hardwired) to the antenna 208 at only one tap point 212 rather than switching between two tap points as depicted in Figures 2A and 2B (210 and 212).
• the connection to the transceiver unit 218 should be flexible enough (or have room inside the casing 202) and long enough to allow the movable portion of the casing 206 to fully open.
• a material such as a stripline, insulated copper wire, or coaxial cable can be used to make a connection to the transceiver unit 218.
• the connection can have an intermediate connector to facilitate the transfer of the antenna signal between the movable and stationary portions of the casing.
• a casing 202 in the alternative embodiment of Figure 4 can also be manufactured to open by pivoting (or flipping) away from the stationary portion of the case 204. Pivoting can be to the outside of the casing 202, relative to the user, or above or below the casing 202
• a digital signal processor taking the place of antenna switch 306 in Figure 3, can be connected to receive signals from both antennas 302 and 308.
• the DSP can evaluate signal quality and dynamically switch the transceiver unit connection between the two antennas according to which connection yields the better signal quality (least signal loss).
• the DSP can combine the signals from both antennas 302 and 308 for connection to the transceiver unit 218.
• FIG. 5 depicts a block diagram of a mobile station 500 that can make use of the disclosed embodiments.
• the mobile station 500 includes, in this example: A control head 502 containing an audio interface, i.e. a speaker 504 and microphone
• the control head 502 generally includes a display assembly 508 allowing a user to see dialed digits, stored information, messages, calling status information, including signal strength, etc.
• the control head generally includes a keypad 510, or other user control device, allowing a user to dial numbers, answer incoming calls, enter stored information, and perform other mobile station functions.
• the control head also has a controller unit 534 that interfaces with a logic control assembly 518 responsible, from the control unit perspective, for receiving commands from the keypad 510 or other control devices, and providing status information, alerts, and other information to the display assembly 508;
• a transceiver unit 512 containing a transmitter unit 514, receiver unit 516, and the logic control assembly 518.
• the transmitter unit 514 converts low-level audio signals from the microphone 506 to digital coding using a codec (a data coder/decoder) 520.
• the digitally encoded audio is represented by modulated shifts, for example, in the frequency domain, using a shift key modulator/demodulator 522.
• Other codes transmission utilized by the logic control assembly 518, such as station parameters and control information, may also be encoded for transmission.
• the modulated signal is then amplified 524 and transmitted via an antenna assembly 526;
• the antenna assembly 526 contains a TR (transmitter/receiver) switch 536 to prevent simultaneous reception and transmission of a signal by the mobile station 500.
• the transceiver unit 512 is connected to the antenna assembly 526 through the TR switch 536.
• the antenna assembly contains at least one antenna 538.
• the antennas described in the disclosed embodiments 208, 302, and 308) and the antenna switch (or DSP) are part of the antenna assembly of the described mobile station;
• the receiver unit 516 receives a transmitted signal via the antenna assembly 526.
• the signal is amplified 524 and demodulated 522. If the signal is an audio signal, it is decoded using the codec 520. The audio signal is then reproduced by the speaker 504. Other signals are handled by the logic control assembly 518 after demodulation 522; and
• a logic control assembly 518 usually containing an application specific integrated circuit (or ASIC) combining many functions, such as a general purpose microprocessor, digital signal processor, and other functions, into one integrated circuit.
• the logic control assembly 518 coordinates the overall operation of the transmitter and receiver using control messages.
• the various disclosed embodiments make use of the logic control assembly to control scanning and evaluation of other base stations.
• the logic control assembly operates from a program that is stored in flash memory 528 of the mobile station. Flash memory 528 allows upgrading of operating software, software correction or addition of new features. Flash memory 528 is also used to hold user information such as speed dialing names and stored numbers.
• the various disclosed embodiments typically function from this or another section of the mobile station's memory.
• the mobile station will typically contain read only memory (ROM) 530 for storing information that should not change, such as startup procedures, and random access memory (RAM) 532 to hold temporary information such as channel number and system identifier.
• ROM read only memory
• RAM random access memory
• the disclosed embodiments have been described in the context of a wireless mobile station without using a specific protocol.
• any wireless communications protocols for example, IS-95, IS-136, CDMA2000, and TDMA, can take advantage of the disclosed embodiments.
• multi-mode mobile stations may take advantage of the disclosed embodiments as well.
• Multi-mode mobile stations may require microstrip antennas with differing tap points for differing modes. Therefore, slight modifications for connection of the multi-mode antenna to the transceiver unit may have to be made.
• multi-band mobile stations may also take advantage of the disclosed embodiments.
• Multi-band mobile stations may require microstrip antennas with differing tap points and lobe configurations for differing bands.
• the disclosed embodiments have been described in the context of a mobile station with a movable casing portion which covers the keyboard.
• a movable casing portion can cover more or less of the mobile station than is depicted in the Figures.
• the casing can be manufactured such that its movable portion does not necessarily cover the keyboard at all.
• a movable portion for the casing containing an antenna can slide either up or down, from the back or side of the mobile station, or from a middle section of the mobile station bounded by stationary front and back sections.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Support Of Aerials (AREA)
• Mobile Radio Communication Systems (AREA)
• Transceivers (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)
• Telephone Set Structure (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=23181327

Family Applications (1)

Country Status (7)

Cited By (1)

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• 2000
  • 2000-05-04 WO PCT/US2000/012295 patent/WO2000067342A1/en not_active Application Discontinuation
  • 2000-05-04 IL IL14529300A patent/IL145293A0/xx unknown
  • 2000-05-04 EP EP00932100A patent/EP1177598A1/en not_active Withdrawn
  • 2000-05-04 AU AU49876/00A patent/AU4987600A/en not_active Abandoned
  • 2000-05-04 JP JP2000616089A patent/JP2004500741A/ja active Pending
  • 2000-05-04 CN CN00807216A patent/CN1349673A/zh active Pending
• 2002
  • 2002-08-05 HK HK02105707.1A patent/HK1044229A1/zh unknown

Non-Patent Citations (1)

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