Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2001-10-24
2003-04-01
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000, C343S767000, C343S846000
Reexamination Certificate
active
06542123
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a hidden wideband antenna, and especially to a modified PIFA (planar inverted F-antenna) of which an open stub is provided to adjust electric matching and increase bandwidth.
2. Description of the Prior Art
A helix antenna of which the spiral coil is formed by winding metallic wires is the major type of antenna. Any of the followings including the diameter or the material of a coil or the pitch between rings of a coil or the total length of a coil of this kind of helix antenna will affect the set function in every aspect. But the defect of such conventional helix antenna resides in three-dimensional protruding out of the equipment. As for communication equipment of the modern miniaturized type or with necessary built-in antennas (such as a mobile phone or a portable computer), it can hardly be surely desirable.
Thus, various miniaturized and planar hidden microstrip antennas were gradually researched and developed. Among the modern applicable embodiments of the planar antennas, the relatively notable one is the planar inverted F-antenna (PIFA). In an early common planar inverted F-antenna as shown in FIG.
1
, a metal wire
11
is provided on a grounding surface
10
, a short point
12
is provided on one end of the metal wire
11
, and a feed point
13
is provided near the short point
12
, the feed point
13
is connected to a feed-in axle
14
. A desired single-frequency antenna can be formed in this way. This early type inverted F-antenna can be developed to get a planar inverted F-antenna as shown in FIG.
2
. Basically it includes a metal surface
15
of a predetermined area, and other related items including a grounding surface
100
, a short point
120
, a feed point
130
and a feed-in axle
140
.
It was stated in “Dual-Frequency PIFA” on page 1451 of “IEEE” published in October of 1997 that, either to merge two separate blocks of different sizes into a rectangular shape or to directly provide an open slot with two mutually perpendicular sections on a rectangular metal surface can form a desired dual frequency PIFA.
Furthermore, a modified planar inverted F-antenna (PIFA) is researched and developed in recent years, which allows further diminishing of the PIFA size to make the antenna length be smaller than ⅛ wavelength (&lgr;) and the antenna height be smaller than 0.01 wavelength (&lgr;), and to have a larger bandwidth (“ELECTRONICS LETTERS”, Jan. 8, 1998, Vol.34 No.1). But the bandwidth is still low in application, and it is hard to be adapted to the modern hidden antennas of dual or multi-frequencies in a more desirable way.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a hidden wideband antenna which is provided on a metal sheet with an open slot to partition it into a long section and a short section. The long and the short sections are both set to have a partial wavelength respectively of multi-resonant frequencies. An inwardly recessed section is provided at a specific position along the long section, and a bent back section is provided on the long section. The bent back section is provided with a protruding portion facing to the inwardly recessed portion and spaced therefrom with a predetermined distance in order to form an open stub to adjust frequency matching and increase bandwidth. This is the prime motive for the present invention.
The present invention will be apparent in its novelty and other features after reading the detailed description of the preferred embodiment thereof in reference to the accompanying drawings.
REFERENCES:
patent: 5644319 (1997-07-01), Chen et al.
patent: 5943020 (1999-08-01), Liebendoerfer et al.
patent: 6114996 (2000-09-01), Nghiem
patent: 6268831 (2001-07-01), Sanford
patent: 6346914 (2002-02-01), Annamaa
patent: 6380905 (2002-04-01), Annamaa et al.
patent: 6408190 (2002-06-01), Ying
patent: 6448932 (2002-09-01), Stoiljkovic et al.
patent: 6456249 (2002-09-01), Johnson et al.
patent: 6483462 (2002-11-01), Weinberger
Auden Techno Corp.
Chen Shih-Chao
Troxell Law Office PLLC
Wong Don
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