Antenna

Details Antenna Antenna

2001-07-20

2003-09-02

Nguyen, Hoang (Department: 2821)

Communications: radio wave antennas

Antennas

With radio cabinet

C343S7000MS, C343S846000

Reexamination Certificate

active

06614400

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a communication device in a radio communication system, and a built-in antenna for a radio communication device.
BACKGROUND OF THE INVENTION
The present invention relates generally to radio communication systems and, in particular, to built-in antennas which can be incorporated into portable terminals and which allow the portable terminals to communicate within different frequency bands.
The cellular telephone industry has made phenomenal strides in commercial operations in the United States, Europe and the rest of the world. Growth in major metropolitan cities has far exceeded expectations and is rapidly outstripping system capacity. If this trend continues, the effects of this industry's growth will soon reach even the smallest markets. Innovative solutions are required to meet these increasing capacity needs as well as maintain high quality service and avoid rising prices.
Throughout the world, one important step in the advancement of radio communication systems is the change from analogue to digital transmission. Equally significant is the choice of an effective digital transmission scheme for implementing the next generation technology, e.g. time division multiple access (TDMA) as for example GSM, GPRS, D-AMPS or code division multiple access (CDMA) as for example CDMA2000, IS-95 or W-CDMA. Furthermore, it is widely believed that the next generation of Personal Communication Networks (PCNs), employing low cost, pocket-sized, cordless telephones that can be carried comfortably and used to make or receive calls and communicate with interactive data bases like the Internet in the home, office, street, car, etc., will be provided by cellular carriers using the next generation digital cellular system infrastructure as for example W-CDMA, GPRS or EDGE. To provide an acceptable level of equipment compatibility, standards have been created in various regions of the world. For example, analogue standards such as AMPS (Advanced Mobile Phone System), NMT (Nordic Mobile Telephone) and ETACS and digital standards such as D-AMPS (e.g., 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 standardise design criteria for radio communication systems. Once created these standards tend to be reused in the same similar form, to specify additional systems. For example, in addition to the original GSM system, there also exists the DCS1800, GPRS (General Package Radio Service), EDGE (Enhanced Data rate for GSM Evolution) (specified by ETSI), PCS1900 (specified by JTC in J-STD-007), all of which are based on GSM.
The recent evolution in cellular communication services involves the adoption of additional frequency bands for use in handling mobile communication services, e.g., for Personal Communication Services (PCS). Taking the U.S. as an example, the Cellular hyperband is assigned two frequency bands (commonly referred to as the A frequency band and the B frequency band) for carrying and controlling communications in the 800 MHz region. The PCS hyperband, on the other hand, is specified in the United States to include six different frequency bands (A, B, C, D, E, F) in the 1900 MHz region. Thus, eight frequency bands are now available in any given service area of the U.S. to facilitate communication services. Certain standards have been approved for the PCS hyperband (e.g., PCS1900 (J-STD-136)), while others have been approved for the Cellular hyperband (e.g., D-AMPS (IS-136)).
Each one of the frequency bands specified for the Cellular and the PCS hyperbands is allocated 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 the mobile station by means of information transmitted or received from the mobile stations. Such information may include incoming call signals, outgoing call signals, page signals, page response signals, location registration signals, voice channel assignments, maintenance instructions, hand-over, and cell selection or reselection instructions as a mobile station travels out of the radio coverage of one cell and into the radio coverage of another cell. The control and voice channels may operate using either analogue modulation or digital modulation.
The signals transmitted by a base station in the downlink over the traffic and control channels are received by mobile or portable terminals, each of which has at least one antenna. Historically, portable terminals have employed a number of different antennas to receive and transmit signals over the air interface. For example, monopole antennas mounted perpendicularly to a conducting surface have been found to provide good radiation characteristics, desirable drive point impedances and relatively simple construction. Monopole antennas can be created in various physical forms. For example, rod or whip antennas have frequently been used in conjunction with portable terminals. For high frequency applications where an antenna's length is to be minimized, another choice is the helical antenna.
As described above, it is commercially desirable to offer portable terminals which are capable of operating in widely different frequency bands, e.g., bands located in 900 MHz region, 1800 MHz region, 1900 MHz region and 2100 MHz region. Accordingly, antennas which provide adequate gain and bandwidth in all above frequency bands will need to be employed in the near future.
For example, U.S. Pat. No. 4,572,595 describes a dual-band antenna having a sawtooth-shaped conductor element. The dual band antenna is tuned to two different frequency bands. The antenna design in this patent is relatively insufficient since it is so physically close to the chassis of the mobile phone.
Japanese patent No. 6-37531 discloses a helix, which contains an inner parasitic metal rod. In this patent, the antenna can be tuned to dual resonant frequencies by adjusting the position of the metal rod. Unfortunately, the bandwidth for this design is too narrow for use in cellular communications.
Dual-band, printed, monopole antennas are known in which dual resonance is achieved by the addition of a parasitic strip in close proximity to a printed monopole antenna. While such an antenna has enough bandwidth for cellular communications, it requires the addition of a parasitic strip. Moteco AB in Sweden has designed a coil matching dual-band whip antenna and coil antenna, in which dual resonance is achieved by adjusting the coil-matching component (¼&lgr; for 900 MHz and ½&lgr; for 1800 MHz). This antenna has relatively good bandwidth and radiation performances and a length in the order of 40 mm. A non-uniform helical dual-band antenna which is relatively small in size is disclosed in copending, commonly assigned U.S. patent application Ser. No. 08/725 507, entitled “Multiple Band Non-Uniform Helical Antennas”.
Presently, antennas for radio communication devices, such as mobile phones, are mounted directly on the phone chassis. However, as the size and weight of portable terminals continue to decrease, the above-described antennas become less advantageous due to their size. Moreover, as the functionality of these future compact portable terminals increases, the need arises for built-in miniature antennas, which are capable of being resonant at multiple frequency bands.
Conventional built-in antennas currently in use in mobile phones include microstrip antennas and planar inverted-F antennas. Microstrip antennas are small in size and light in weight. The planar inverted-F antenna (PIFA) has already been implemented in a mobile phone handset, as described by Q.Kassim, “Inverted-F Antenna for Portable Handsets”, IEE Colloquium on Microwave filters and Antenna for personal Communication systems, pp. 3/1-3/6, February 1994, London, UK. More recently, Lai et al has published a meandering inverted-F antenna (WO 96/27219). This antenna has a size, which is about 40% of that of a conventional PIFA antenna.
FIGS. 1 and 2
illustrate the

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