Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
1999-07-08
2001-03-06
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S777000, C343S846000
Reexamination Certificate
active
06198437
ABSTRACT:
BACKGROUND OF THE INVENTION
Several transmission line and antenna arrangements compatible with printed circuit embodiment of microwave electronic apparatus are known in the electronic arts and have found application in radar, satellite communication and other present day systems. In these systems a transmission line realized in the form of printed circuit conductors is often used to communicate radio frequency energy to or form an antenna element.
The printed circuit conductor in these embodiments may for example be arranged in the form of what is known as “stripline”, an arrangement wherein a strip conductor is received between two adjacent ground planes, or alternately in the form of “microstrip” line wherein a single conductor is spaced from a single ground plane. The printed circuit conductor may also be in the form of “slot” line wherein a slot formed in one planar conductor is spaced from a second ground plane conductor. Another common arrangement for such printed circuit transmission line is known as coplanar waveguide line and is in the form of an electrically isolated signal conductor bounded laterally by adjacent ground plane conductors in a coplanar disposition.
Some of these transmission line types have also been used in configurations wherein an apparent part of one or more transmission line elements also functions as an active element portion of an antenna, an antenna coupled to the transmission line. In these arrangements the transmission line and antenna element portions may appear structurally integral however for functional and analysis purposes a segregation of functions is convenient. This combination of transmission line and antenna functions in single structure has been achieved particularly in the case of microstrip transmission lines. Unlike the case of such microstrip antennas there appears to be little reporting in the technical literature concerning wide strip coplanar waveguide lines or open ended discontinuities and their radiating properties, areas of consideration in the present invention.
This latter transmission line disposition which has been identified by the name of “coplanar waveguide” offers several advantages including its easy layout and fabrication by single layer photographic techniques and acceptable electrical losses. The ease with which coplanar transmission line of this nature can be coupled to resonators and antenna elements is also significant and approaches the topic of interest in the present invention. Perhaps the most convenient of antenna arrangements usable with coplanar waveguide transmission line is the antenna known as a “patch” antenna. Literally such antennas may consist of a printed circuit conductor area of selected and resonance-based physical size disposed at the terminal point or other selected node along a radio frequency conductor. When used with the above identified microstrip form of printed circuit transmission lines for example the patch antenna is found to be attended by several problems; the primary of which is a limited bandwidth capability. This patch antenna bandwidth often extends over only a few percent of the antenna's design frequency and gives rise to difficulty in spread spectrum communications or multiple systems use applications of the antenna. The present invention in which the patch antenna is improved-upon by combining it with a selected additional form of antenna while yet remaining in the convenient and desirable coplanar waveguide environment is believed to provide a desirable addition to the family of antennas usable in printed circuit microwave apparatus.
SUMMARY OF THE INVENTION
The present invention provides a microwave antenna of desirable wide bandwidth electrical characteristics and concurrent compatibility with the coplanar waveguide form of radio frequency transmission line.
It is an object of the present invention therefore to provide a broadband microwave antenna.
It is another object of the invention to provide a broadband antenna having compatibility with the coplanar waveguide form of transmission line and with coplanar waveguide antenna practices.
It is another object of the invention to provide a broadband microwave antenna combining desirable characteristics of two different antenna types known in the art.
It is another object of the invention to provide a broadband microwave antenna combining the characteristics of a patch antenna with those of a slot antenna.
It is another object of the invention to provide a broadband microwave antenna of the single layer or single plane type.
It is another object of the invention to improve on the multiple layer multiple plane types of antennas known in the electronic art; antennas of the types often used in the microstrip transmission line environment for example.
It is another object of the invention to provide a broadband coplanar antenna in which multiple resonances may be individually treated and tailored to achieve a desired broadband antenna characteristic.
It is another object of the invention to provide a broadband antenna in which a thirty percent usable bandwidth is achievable in for example the seven gigahertz operating frequency range.
It is another object of the invention to provide a broadband coplanar microwave antenna, easily fabricated with printed circuit and similar materials.
It is another object of the invention to provide a broadband coplanar microwave antenna usable in multiple antenna environments such as in an electronically steered radar antenna array.
It is another object of the invention to provide a broadband coplanar microwave antenna readily adapted to use in vehicles including aircraft for uses such as communications, radar and electronic warfare systems.
It is another object of the invention to provide a broadband coplanar microwave antenna capable of accurate, convenient performance modeling and characteristic tailoring.
Additional objects and features of the invention will be understood from the following description and claims and the accompanying drawings.
These and other objects of the invention are achieved by broadband combination patch and slot coplanar microwave antenna apparatus comprising the combination of:
an electrical conductor ground plane member disposed on an electrically insulating planar substrate member;
said ground plane member including a rectangular shaped electrical conductor aperture having orthogonally disposed shorter and longer aperture sides received in a ground plane interior portion;
a coplanar rectangularly shaped electrically conductive patch antenna member symmetrically received in electrical isolation within said ground plane conductor rectangular aperture on said electrically insulating planar substrate member;
said electrically conductive patch antenna member being characterized by first and second diametrically opposed radiating edge portions, of respective first and second patch antenna electrical resonance frequency characteristics and disposition adjacent respective ground plane conductor shorter aperture sides;
a first electrical slot resonator inclusive of said first electrically conductive patch antenna member first radiating edge, an adjacent ground plane aperture shorter side conductor and an intervening non-conducting exposed substrate area, said first electrical slot resonator having a first slot antenna electrical resonance frequency characteristic;
a second electrical slot resonator inclusive of said second electrically conductive patch antenna member second radiating edge, an adjacent ground plane aperture shorter side conductor and an intervening non-conducting exposed substrate area, said second electrical slot resonator having a second slot antenna electrical resonance frequency characteristic;
a transmission line conductor element coplanar received within an elongated ground plane void pathway and communicating radio frequency electrical energy among a region peripheral of said ground plane member and said electrically conductive antenna member in said rectangular shaped electrical conductor aperture.
REFERENCES:
patent: 4063246 (1977-12-0
Gupta Kuldip C.
Watson Paul M.
Hollins Gerald B.
Kundert Thomas L.
Phan Tho
The United States of America as represented by the Secretary of
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