Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
1999-09-10
2001-02-27
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000, C343S846000
Reexamination Certificate
active
06195049
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a micro-strip patch antenna for a radiotelephone transceiver.
2. Description of the Related Art
Mobile radio terminals, such as portable radiotelephones, are getting smaller and lighter. In wireless communications, the antenna has a great influence on the performance of the radiotelephone. The antenna is the interface between the radiotelephone and free space. Since most “regular-sized” antennas exhibit close-to-theoretical performance when outside influence is not significant, they typically can easily be designed. Small antennas, however, have low radiation efficiency and a narrow frequency bandwidth. In addition, since a current may be induced in the radiotelephone body by electromagnetic interaction between antenna elements and the radiotelephone body, an electromagnetic wave may be radiated in an unexpected direction.
The types of linear antennas generally used in portable radiotelephones are the &lgr;/2 monopole antenna (the length of which is set to half of the wavelength of the electromagnetic wave employed), a &lgr;/4 monopole antenna (an improved version of the &lgr;/2 monopole antenna), and a &lgr;/2 whip antenna. These antennas have a length of 16 or 8 cm when the employed frequency is 900 MHz or 1.9 GHz, respectively, and can be enclosed in the radiotelephone body.
When the 900 MHz band is assigned as the frequency for radiotelephone communication, however, the length of the antenna must be 16 cm so as to receive the electromagnetic wave with the &lgr;/2 monopole antenna.
Since the length of the above monopole antennas is relatively long, as depicted in
FIG. 1
, a radiotelephone using a monopole antenna as described above must use an external antenna
3
which projects outward from the radiotelephone body
1
.
In a radiotelephone having such an external antenna, as illustrated in an RF (radio frequency) characteristic curve shown in
FIG. 2
, it is difficult to attain the maximum gain at the upper and lower limit frequencies actually containing receiving (Rx) and transmitting (Tx) communication signals. Therefore, when the bandwidth is set to be wide (so as to attain the maximum gain), there arises a problem in that noise tends to interfere with the signal wave easily. Further, the monopole type external antenna is an element that severely limits the freedom of the designer in designing the radiotelephone.
A known alternative to the monopole type external antenna is the general micro-strip patch antenna. The general micro-strip patch antenna, although more compact, has several drawbacks, as will now be described.
A general micro-strip patch antenna may use a dielectric ceramic, but requires two dielectric ceramic element parts for transmitting and receiving signals when the transmission and reception bandwidths are different from each other (as is usually the case with portable radiotelephones).
FIG. 3
shows a conventional internal antenna with a transmitting patch
30
, a transmitting dielectric ceramic
32
, a common ground
34
, a receiving dielectric ceramic
36
, and a receiving patch
38
. In a radiotelephone having separate transmitting and receiving frequency bandwidths, the two dielectric antennas, which respectively perform the transmitting and receiving functions, are bonded to each other with the transmitting and receiving patches
30
and
38
facing outward.
Thus, such an antenna really is two dielectric antennas (one for transmission and one for reception), and it is difficult to reduce the size of a portable radiotelephone using such a general micro-strip antenna.
There are other problems with the general micro-strip antenna. For one thing, the supplying of power from what is typically a sole power supply point to the dielectric antennas is difficult, and it is also difficult to draw a common ground line. Further, the unit price of this type of antenna is high, and they are heavy enough to contribute significantly to the total weight of a radiotelephone. Furthermore, since the power to the antennas is normally supplied through only one channel, there is a disadvantage in that the main circuit of the radiotelephone must be altered because of the use of two antennas.
SUMMARY OF THE INVENTION
To solve the above and other problems, it is an objective of the present invention to provide a single micro-strip patch antenna for a portable radiotelephone transceiver which is internal, compact, capable of transmission and reception with only one dielectric ceramic part, and yet operable with separate transmission and reception frequency bandwidths by virtue of matching the antenna impedance to a main circuit impedance, and by supplying power to two frequency bandwidth terminals from one power supply source using strip lines on a printed circuit board.
Accordingly, to achieve the above objective, there is provided a micro-strip patch antenna for a radiotelephone transceiver including: a dielectric ceramic module for transmission and reception having a first ground plate, a dielectric ceramic mounted on the first ground plate for synchronizing frequencies, a conductive patch mounted on the dielectric ceramic for transmitting and receiving electromagnetic waves, a transmission power supply terminal formed to project from one side of the conductive patch to supply power for transmission, and a reception power supply terminal formed to project from another side of the conductive patch to supply power for reception; and a printed circuit board having a base, a second ground plate mounted on the base to contact the first ground plate, and strip lines formed on the base to be adjacent to the first ground plate and connected to the transmission and reception power supply terminals.
REFERENCES:
patent: 5861854 (1999-01-01), Kawahata et al.
patent: 5909198 (1999-06-01), Mandai et al.
patent: 5969680 (1999-10-01), Tsurn et al.
patent: 5977915 (1999-11-01), Bergstedt et al.
patent: 6061025 (2000-05-01), Jackson et al.
Kim Duck-su
Kim Young-eil
Lee Sung-Soo
Chen Shih-Chao
Le Hoang-anh
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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