Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-07-19
2001-07-24
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S853000
Reexamination Certificate
active
06266015
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to phased array antennas, and more particularly, this invention relates to phased array antennas used at millimeter wavelengths.
BACKGROUND OF THE INVENTION
Microstrip antennas and other phased array antennas used at millimeter wavelengths are designed for use with an antenna housing and a MMIC (millimeter microwave integrated circuit) subsystem assembly used as a beam forming network. The housing can be formed as a waffle-wall array or other module support to support a beam forming network module, which is typically designed orthogonal to any array of antenna elements. Various types of phased array antenna assemblies that could be used for millimeter wavelength monolithic subsystem assemblies are disclosed in U.S. Pat. No. 5,065,123 to Heckaman, the disclosure which is hereby incorporated by reference in its entirety, which teaches a waveguide mode filter and antenna housing. Other microwave chip carrier packages having cover-mounted antenna elements and hermetically sealed waffle-wall or other configured assemblies are disclosed in U.S. Pat. No. 5,023,624 to Heckaman and U.S. Pat. No. 5,218,373 to Heckaman, the disclosures which are hereby incorporated by reference in their entirety. In the '624 patent, residual inductance of short wire/ribbon bonds to orthogonal beam forming network modules is controlled.
There are certain drawbacks associated with these and other prior art approaches. Above 20 and 30 GHZ, commercially available soft substrate printed wiring board technology does not have the accuracy required for multilayer circular polarized radiation elements, such as quadrature elements. A single feed circular polarized patch antenna element with an integral hidden circular polarized circuitry is desired for current wide scanning millimeter microwave (MMW) phased array applications. Various commercially available soft substrate layers have copper film layers that are thicker than desired for precision millimeter microwave circuit fabrication. Several bondable commercially available soft dielectric substrates have high loss at microwave millimeter wavelengths and the necessary rough dielectric-to-metal interface causes additional attenuation. Many commercially available dielectric substrates are not available in optimum thicknesses. Various dual feed microstrip elements with surface circuit polarized networks have been provided and some with polarizing film covers, but these have not been proven adequate. It would be desirable to minimize the different layers and use microwave integrated circuit materials and fabrication technologies for a phased array antenna with orthogonally positioned beam forming network modules at millimeter microwave wavelengths.
Additionally, the recent trend has been towards higher frequency phased arrays. In Ka-band phased array antenna applications, the interconnect from the element to the beam forming network modules is very difficult to form because the array face is typically orthogonal to the beam forming network modules and any antenna housing support structure.
Fully periodic wide scan phased array antennas require a dense array of antenna elements, such as having a spacing around 0.23 inches, for example, and having many connections and very small geometries. For circular polarized microstrip antennas, there are normally two quadrature feeds required, making the connections even more difficult at these limited dimensions. Some planar interconnects with linear polarization have been suggested, together with a pin feed through a floor if the area allows. Also, any manufacturable, reworkable interconnect that meets high performance requirements for three-dimensional applications with millimeter microwave integrated circuit technology is not available where planar elements must be electrically connected to circuitry positioned orthogonal to elements and meet the microwave frequency performance requirements. Performance must be consistent for each interconnection and the technology must be easily producible and easily assembled where the interconnection must be repairable at high levels of assembly. The technology must also support multiple interconnects over a small area.
SUMMARY OF THE INVENTION
The present invention is advantageous and provides a phased array antenna that uses a stacked patch antenna element and a single millimeter wavelength feed from a microstrip quadrature-to-circular polarization circuit. This allows the microstrip quadrature-to-circular polarization circuit to be operatively connected with a respective adjacent beam forming network module supported on the orthogonally positioned subarray assembly.
The phased array antenna includes an antenna housing having a subarray assembly that supports a plurality of beam forming network modules. An antenna array face defines a ground plane substantially orthogonal to the subarray assembly. A plurality of millimeter wavelength patch antenna elements are positioned on the array face adjacent a respective beam forming network module. The millimeter wavelength patch antenna elements each comprise a driven antenna element having front and rear sides and a parasitic antenna element positioned forward of the front side of the driven antenna element. A microstrip quadrature-to-circular polarization circuit is positioned rearward of the rear side of the driven antenna element and operatively connected to the driven antenna element. A single millimeter wavelength feed is operatively connected to the microstrip quadrature-to-circular polarization circuit and to a respective adjacent beam forming network module supported on the orthogonally positioned subarray assembly.
In one aspect of the present invention, the phased array antenna includes a ground plane layer and a dielectric layer formed between the parasitic antenna element and the microstrip quadrature-to-circular polarization circuit. The single millimeter wavelength feed further includes a conductive pin having a ball bond that interconnects the microstrip quadrature-to-circular polarization circuit. A wedge bond and ceramic microstrip substrate interconnects the conductive pin to the beam forming network module. A single millimeter wavelength feed includes a wire bond that interconnects the ceramic microstrip substrate to the beam forming network module.
A ribbon bond interconnects the single millimeter wavelength feed to the ceramic or other components. A plurality of millimeter wavelength patch antenna elements are conductively bonded to the array face of the antenna housing. The beam forming network includes an amplifier and a monolithic microwave integrated circuit (MMIC) and a connecting ceramic microstrip substrate. The antenna housing includes a housing core defining the subarray assembly, module support, a cover and waveguide mode filter post extending from the cover to the housing core.
In still another aspect of the present invention, the antenna housing includes a plurality of module supports that each support a beam forming network module and an array face substantially orthogonal to the module supports. The array face includes a plurality of waveguide below cut-off cavities formed within the array face and each positioned adjacent a respective module support.
A millimeter wavelength patch antenna element is positioned over each waveguide below cut-off cavity and includes a driven antenna element having a front and rear side and a parasitic antenna element positioned forward of the front side of the driven antenna element. A quadrature microstrip circular polarized circuit is positioned rearward of the rear side of the driven antenna element, at least partially received within the waveguide below cut-off cavity and operatively connected to the driven antenna element. A single millimeter wavelength feed connects the microstrip quadrature-to-circular polarization circuit and a respective adjacent beam forming network module supported on the orthogonally positioned subarray assembly.
In yet another aspect of the present invention, the phased array antenna can include an
Bajgrowicz Edward J.
Boozer Randy E.
Heckaman Douglas E.
Jandzio Gregory M.
Nichols James B.
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Harris Corporation
Ho Tan
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