Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
1999-11-22
2001-10-16
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S846000
Reexamination Certificate
active
06304219
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns an antenna intended for reception and transmission of electromagnetic microwaves in the wavelength range of &lgr; and consisting of a substrate layer of low dielectric material that is structured on one side with a conductive ground plane and whose opposing side is conductive in the form of micro-strip circuits.
The area of application of the invention extends fundamentally to the mobile communications and handheld technologies within the spectral range of between 890 MHz and 960 MHz or 1710 MHz and 1890 MHz whereby the components described in the invention are integrated into the respective terminal devices and handheld technologies.
2. Description of Related Art
Familiar antenna solutions for the area of mobile communications applications are based on linear antenna designs in the form of single-pole applications in shortened or unshortened execution. These linear antennas are familiar both as externally installed aerial antennas [Bordantennen] an as components that are integrated directly with the terminal device, as well as those affected by various directional factors and effectiveness, whereby these components are exclusively omnidirectional at the azimuth level. Familiar flat antenna solutions are based on planar arrangements similar to dipolar configurations whose radiation pattern is irregular and exhibits and, in conjunction with the respective antenna support or antenna body, the characteristics of a significant radiation field deformations. The radiation field properties relevant to the area of application are clearly inferior to those of the classical linear antenna. Likewise, fade or tune out properties of the radiation pattern are not demonstrable. Furthermore there are no known solutions, whose electromagnetic or radiation characteristics are achieved on the basis of asymmetrical and open wave guide technology, particularly that of micro-strip technology, using foil circuitry or foil-like conducting surfaces.
The azimuth omnidirectional antenna configuration elaborated in Patent DE 41 13 277 proceeds exclusively from a foil as a structural support, whereby the described antenna component is subject to a capacitative top loading outside of the terminal device container. In like manner, the azimuth omnidirectional antenna configuration illustrated in Patent DE 41 21 333 starts with an electrically non-conducting foil as a mechanical structural support, whereby the main radiation direction with respect to the elevations exhibits a slope of approximately (minus) −30° (degrees of angle); that is, it exhibits a negative elevation angle.
SUMMARY OF THE INVENTION
Thus, the disadvantage of the conventional antenna configurations is that they either are exclusively omnidirectional at the azimuth level or radiate merely within the negative angle range.
The purpose of the invention described herein is to provide a system integratable antenna component with the smallest possible surface expansion having the most unidirective azimuthal directional effect; that is, it provides the preferred coverage of a spatial hemisphere as well as a limited angular shift within the positive range of elevation angle.
This purpose is achieved by the invention described herein by the characteristics of the identifying portions of Claim
1
and the subordinate claims that refer back to Claim
1
.
In the case of the antenna described in the invention and which can be characterized as a radiating foil, we refer to a modified &lgr;/4 radiator [antenna] which is shorted on the one side against ground. In order to achieve the most compact construction the longitudinal conductor segment, which serves as the resonator, is designed as &lgr;/4. In this manner, the resonator becomes, however, inductive and the vibratory condition is not fulfilled. At the opposing end of the resonator on the side to be shorted, an end capacitance is produced so that the resonance requirement [condition] can be obtained. Said end capacitance is produced by at least on additional conductive segment which is connects to the end of the resonator lying opposite the side to be shorted and which forms an open circuit [no-load] at its other end. The length of the additional conductive segment determined by the vibratory condition and thus the resulting resonance frequency of the entire structure. Here, various design forms of the conductive segment at the end of the resonator are conceivable for the realization of a defined end capacitance. The end capacitance can be realized by one or several circuits of appropriate lengths that do not necessarily have to be parallel to one another or run to the resonator. All circuits can likewise be laid out in whatever curvature and not exclusively straight linear form.
By covering the antenna or the foil radiator foil using an additional dielectric layer, which is not considered in the design process, significant desensitization vis-à-vis other dielectrics in proximity to the radiator (antenna) can be achieved. This is important in that by integrating the foil antenna into radio devices (dielectric effect) and by the affect that results by holding the radio device in the hand, functionality is preserved and the antenna is not detuned or maladjusted.
Since in this type of antenna the one side is shorted, there is only one transmitting or receiving end. This results in a dyssymmetry or the directive characteristics in the vibratory plane of the electrical field vectors (E-planes) and thus in an angular shift of the main transmission direction in said plane of approximately 30° in the line of sight on the shorted transmitter side—transmitting end.
The electrical properties of these antennas; such as, for example, quality, impedance bandwidth, gain and efficiency depend on the size of the mechanical shortening attained (reduction), the breadth of the resonator, the distance between the resonator and the end capacitance circuit segments, the effective permissibility [permitivität] constants, the substrate thickness or the dielectric loss angle.
By using the present invention, it is possible to install two or more antennas for different wavelengths in a relatively small space. An essential characteristic of the invention is that the resonators realized using micro-strip technology for receiving the microwaves are created shorter than &lgr;
g
/4 and, as already mentioned, the vibratory condition is no longer met. The required end capacitances are realized by additional conductor segments. An enlargement of the frequency bandwidth can be achieved by additional antenna elements by electromagnetic coupling. This is done by additional micro-strip circuits that are arranged at certain intervals to the resonator and its end capacitances. It is possible, using two or more resonators on a single substrate, to receive several wavelengths, whereby the resonators can be spatially arranged interleaved within one another and tuned to the required frequency bands. The individual antennas need not be arranged on one plane, but can also be arranged in layers. In this manner it is also possible, that per layer several antenna arrangements can be provided, so that more than two different frequency bands are served. In this situation it is possible that a mobile radio-telephone can communicate with different mobile communications networks.
These and other features of the invention will be more understood by reference to the following drawings:
REFERENCES:
patent: 5075691 (1991-12-01), Garay et al.
patent: 5663639 (1997-09-01), Brown et al.
patent: 5666091 (1997-09-01), Hikita et al.
patent: 5748149 (1998-05-01), Kawahata
patent: 5867126 (1999-02-01), Kawahata et al.
patent: 6008762 (1999-12-01), Nghiem
patent: 6049314 (2000-04-01), Munson et al.
Ho Tan
Woodbridge Richard C.
Woodbridge & Associates P.C.
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