Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-09-27
2001-09-25
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S895000
Reexamination Certificate
active
06295029
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a miniature microstrip antenna, and especially to a microstrip antenna of which the size is reduced but the antenna still keeps the broadband function in all the directions.
2. Description of the Prior Art
Coil antennae with spiral structures are widely used in various communication instruments; the most common ones are mobile phones. Basically, such coil antennae are exposed. In the recent years however, notebook style computers with communication function adopt built-in microstrip antennae.
Earlier microstrip antennae, such as those disclosed in the U.S. Pat. Nos. 3,921,177 and 3,810,183, are normally made from round or rectangular thin metallic sheets, they are separated from ground sheets with filled-in dielectric material, such microstrip antennae generally only suit narrower bandwidths. U.S. application Ser. No. 07/695686 , now abandoned, provides a polygonal spiral microstrip antenna having improvement on the earlier microstrip antennae, the bandwidth thereof approaches a normal antenna with a predetermined impedance. However, such a spiral microstrip antenna has the defect that, when in the condition of low frequency, the diameter of the antenna will be quite enlarged such that it will not suit modern communication instruments carried on one's own.
To this, Taiwan patent No. 81108896 (U.S. application Ser. No. 07/798700), now abandoned, provides a reduced and broadband microstrip antenna, but a spiral antenna element is provided on a separated ground sheet, and a kind of dielectric material and load of predetermined thickness are interposed therebetween, so that size of the whole antenna can hardly be further reduced.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a miniature microstrip antenna of which the size can be further reduced but the antenna still keeps the broadband function in all the directions.
To get the above stated object, the present invention has a ¼&lgr; microstrip line rolled on the surface of a circuit board in the shape of a rectangular spiral, the end of the rectangular spiral microstrip line is connected vertically to a {fraction (1/20)}&lgr; microstrip line as an open-stub, the junction of the rectangular spiral microstrip antenna with the open-stub acts as a signal feeder point. A ground plane being also provided on the surface of the circuit board is located beside the signal feeder point but is not connected with the signal feeder point. The ground plane can also make a harmonic oscillation frequency shifting by punching holes to form a miniature microstrip antenna which keeps the broadband effect in all the directions.
The present invention will be apparent in its novelty and other characteristics after reading the detailed description of the preferred embodiment thereof in reference to the accompanying drawings. Wherein:
REFERENCES:
patent: 5712647 (1998-01-01), Shively
patent: 5936583 (1999-08-01), Sekine et al.
patent: 6204826 (2001-03-01), Rutkowski et al.
Chen I-Fong
Lee Meng-Luen
Auden Techno Corp.
Dougherty & Troxell
Ho Tan
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