Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2002-10-28
2004-05-11
Chen, Shih-Chao (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000, C343S893000
Reexamination Certificate
active
06734825
ABSTRACT:
FIELD OF INVENTION
The invention relates generally to radio communication systems. In particular, the invention relates to built-in antennas for radio communication devices for enabling the radio communication devices to perform radio communication in different radio frequency bands.
BACKGROUND
Presently, many antennas, such as monopole antennas or helical antennas, for radio communication devices, such as mobile phones, are mounted directly onto the chassis of radio communication devices. However, as the sizes and weights of such radio communication devices continue to decrease because of advancing research and development, such monopole or monopole-like antennas become more of a hindrance than advantage due to the inherent sizes. Additionally, as the functionality of these radio communication devices expands rapidly, the need arises for built-in miniature antennas that are capable of being resonant at multiple frequency bands.
Conventional built-in antennas currently used in mobile phones include microstrip antennas, wire-form shaped inverted-F antennas (IFA), and planar inverted-F antennas (PIFA). Microstrip antennas are small in size and light in weight. However, at lower radio frequency bands for mobile communication applications, such as the GSM900 band centred on the radio frequency 900 MHz, microstrip antennas become too large for incorporation into a mobile phone. As an alternative, the planar inverted-F antenna (PIFA) can be implemented in a mobile phone, as proposed by Q. Kassim in “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. Such a conventional PIFA, which has a length equal to a quarter wavelength of the centre or operating frequency of the radio frequency band of interest, however operates in a narrow frequency range.
In addition to reduced antenna sizes, it is envisaged that next generation mobile phones require the capability to tune to a number of radio frequency bands for cellular applications, wireless local area networking applications and other radio communication applications. Dual-frequency band PIFA radiating elements are therefore proposed in “Dual-frequency planar inverted-F antenna” by Z. D. Liu, P. S. Hall, and D. Wake, IEEE Trans AP, vol.45, no.10, pp.1451-1457, October 1997. Such dual-frequency band antennas utilise two feeding points and share a common feeding point, respectively, and are associated with either complicated feeding structures or narrow bandwidths.
In U.S. Pat. No. 6,166,694 entitled “Printed Twin Spiral Dual Band Antenna”, a multiple frequency band, built-in antenna is proposed that is suitable for future generations of mobile phones. This built-in antenna comprises two spiral conductor and resonant arms that are of different lengths and capable of being tuned to different frequency bands. In order to increase the bandwidth of such an antenna, a resistor loading technique is introduced. However, the improvement in bandwidth is obtained at the expense of antenna gain of such a built-in antenna.
Currently, many mobile phones operate in one or more of the following three frequency bands: the GSM band centred on the radio frequency 900 MHz, the DCS band centred on the radio frequency 1800 MHz, and the PCS band centred on the radio frequency 1900 MHz.
In U.S. Pat. No. 6,343,208 entitled “Printed Multi-Band Patch Antenna”, a built-in patch antenna is proposed which includes patch elements of different sizes that are capable of being tuned to different frequency bands. Such an antenna experience problems tuning to multiple frequency bands while simultaneously having a broad bandwidth in each of the multiple frequency bands.
More recently, triple-band built-in antennas at operational at the GSM/DCS/PCS bands as shown in
FIGS. 1 and 2
are proposed in PCT application number WO01/91233 and U.S. patent application Ser. No. 09/908,817, respectively. These antennas include a main radiator operating at a low frequency band and a first high band and a shorted parasitic radiator operating at a second high band. The parasitic radiator lies in the same plane with the main radiator and therefore occupies valuable space in mobile phones that are constantly shrinking in size. Moreover, the parasitic-feed technique used for the additional parasitic radiator may have problems in tuning of the parasitic radiator. In practice, for the parasitic-feed technique, it is difficult to tune the parasitic radiator because of the mutual coupling between antenna elements. Tuning one resonant frequency adversely changes another resonant frequency simultaneously.
In respect of the foregoing proposed antennas, a number of problems still exist. Firstly, the sizes of the prior art antennas are still large. Secondly, there is a trend for built-in antennas used in radio communication devices providing quad-frequency band operations to cover GSM900, DCS1800, PCS1900 and 3G bands. Additionally, it is not unforeseeable for these radio communication devices to provide five-frequency band operations to cover the GSM900, DCS1800, PCS1900, 3G and ISM2450 bands simultaneously. Existing built-in antennas are however unable to cover these frequency bands simultaneously.
Thirdly, these antennas have problems tuning to multiple frequency bands while simultaneously having a broad bandwidth in each of these multiple frequency bands. Finally, the parasitic-feed technique used for additional parasitic radiators may have problems in tuning the matching of the parasitic radiators. In practice, for the parasitic-feed technique, it is difficult to perform tuning because of the mutual coupling between antenna elements. Tuning of one resonant frequency changes another resonant frequency simultaneously.
There is therefore a need for a built-in antenna for addressing the foregoing problems.
SUMMARY
In accordance with an aspect of the invention, there is provided a multiple frequency band antenna comprising:
a first resonant portion tuned to a low frequency band;
a second resonant portion tuned to a first high frequency band at frequencies higher than the low frequency band;
a third resonant portion tuned to a second high frequency band at frequencies higher than the low frequency band and substantially different from the first high frequency band; and
a first conductor portion forming part of the first resonant portion and the second resonant portion, the first conductor portion having
a grounding point,
a feeding point for providing an input signal to at least one of the first resonant portion and the second resonant portion and for receiving an output signal from at least one of the first resonant portion and the second resonant portion, and
a second conductor portion electrically connected to the feeding point wherein the third resonant portion is electrically connected to the second conductor portion.
REFERENCES:
patent: 6166694 (2000-12-01), Ying
patent: 6343208 (2002-01-01), Ying
patent: 6552686 (2003-04-01), Ollikainen et al.
patent: 6614399 (2003-09-01), Trumbull et al.
patent: 6639560 (2003-10-01), Kadambi et al.
patent: 6650294 (2003-11-01), Ying et al.
patent: 6650295 (2003-11-01), Ollikainen et al.
patent: 2002/0019247 (2002-02-01), Egorov
patent: WO 01/91233 (2001-11-01), None
Zi Dong Liu et al., Oct. 1997: “Dual-Frequency Planar Inverted-F Antenna”, in IEEE Transactions on Antennas and Propagation, vol. 45, No. 10, pp. 1451-1458.
Chen Zhining
Chia Yan Wah Michael
Guo Yongxin
Chen Shih-Chao
Nath & Associates PLLC
Novick Harold L.
The National University of Singapore
LandOfFree
Miniature built-in multiple frequency band antenna does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Miniature built-in multiple frequency band antenna, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Miniature built-in multiple frequency band antenna will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3190304