Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
1999-10-04
2001-02-13
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S853000
Reexamination Certificate
active
06188361
ABSTRACT:
The invention relates to an active antenna panel of multilayer structure.
It relates particularly but not exclusively to active antenna systems for satellites designed to handle one or more beams via a single panel of radiating elements by means of a beam distributor of multilayer structure.
BACKGROUND OF THE INVENTION
Such satellite active antenna systems need to be of ever-increasing complexity in terms specifically of the number of beams (m) handled by a single radiating panel (of n radiating elements). The complexity and the missions of the beam distributor are thus increased, since it becomes necessary firstly to provide power division from m×1 to m×n, and secondly to provide recombination from m×n to 1×n:
routing then becomes more dense and thus more difficult, particularly when providing identical electrical path lengths for all of the signals; losses increase inevitably; and
the presence of a plurality of beams make it necessary for the illumination law of each pencil in terms of amplitude and phase to be handled within the distributor itself, between the division and recombination functions, which makes it essential to integrate chips (attenuator, phase shifter) within the distributor.
Finally, the inevitable increase in frequency makes the techniques and technologies that have traditionally been used less and less suitable for implementing active antenna distributors.
At present, so-called organic multilayer printed circuit board (PCB) technologies are those which are most suited to the beam distributor problem. Nevertheless, they turn out to be more or less inappropriate under certain conditions, such as:
when the operating frequency exceeds 20 GHz. Under such circumstances, the RF multilayer interconnection techniques usable in that technology (in particular plated-through holes (PTHs)) are limited by the present state of the art; and
for chip integration within the distributor itself since the method of making multilayer PCBs (lamination, pressure, thermofusion) is generally incompatible with any component in relief that it is desired to insert in the multilayer structure. This drawback makes it necessary to offset the chips outside the distributor.
Finally, distributors are built using a horizontal stacking model for the layers parallel to the plane of the antenna, which gives rise to major constraints on performance (generally narrow band) and the space occupied by the interconnections with the radiating elements which are then disposed perpendicularly to the distributor.
Such interconnection can be provided only via the edges of the circuit, which constitutes a major drawback for a “horizontal” distributor: increased losses to take signals to the edges are unacceptable, and the routing density on the edges which offer very little room provides no simplification compared with other solutions.
OBJECTS AND SUMMARY OF THE INVENTION
The invention thus seek to mitigate the above-mentioned drawbacks.
The invention thus provides an active antenna panel that allows chips to be integrated without difficulty within the distributor itself.
Another object of the invention is to provide such a panel of size in terms of interconnections and circuits that is small compared with prior art solutions.
To this end, the invention provides an active antenna panel having a main plane and including an array of n radiating elements and a multilayer-structure m-beam distributor for feeding the n radiating elements, the distributor having first “forming” layers for supporting beam-forming means, and second “connection” layers for supporting first electrical connection means for interconnecting the first layers, and second electrical connection means for connection to the radiating elements.
According to the invention:
the forming layers extend substantially perpendicularly to the main plane of the antenna;
the forming layers and the connection layers are assembled together by molding so that the beam distributor constitutes a single block; and
the radiating elements are connected directly to the second connection means.
This vertical multilayer topology using molding technology enables the coplanar RF three-dimensional interconnection to be reused by one of the connection layers, the only technique presently known for three-dimensional transition that provides high performance over a broad band width. This thus makes it possible to envisage a broad range of applications without any variation in concept or technology.
In an embodiment, the single block is a flat rectangular parallelepiped, the connection layers extending substantially parallel to the plane of the antenna and including a front connection layer having the second connection means and a rear connection layer having the first connection means, the radiating elements being fitted directly on said front connection layer.
The RF three-dimensional interconnection zone of the edges of the “horizontal” solutions are thus offset towards the front and rear connection layers of the distributor, which layers are much more roomy.
RF three-dimensional interconnection routing then becomes very simple and much easier to optimize. In addition, the same area is available as in horizontal multilayer technology for the purpose of conveying signals.
REFERENCES:
patent: 4977406 (1990-12-01), Tsukamoto et al.
patent: 5453751 (1995-09-01), Tsukamoto et al.
patent: 5471220 (1995-11-01), Hammers et al.
patent: 0 398 555 A2 (1990-11-01), None
patent: 0 620 613 A2 (1994-10-01), None
P. Ulian et al, “3D Active Modules for High Integration Antennas” Proceedings of the European Microwave Week, Including 28thEuropean Microwave Conference, vol. 1, Oct. 5-6, 1998, pp. 271-276, XP002106338.
F. Coromina et al, “New Multibeam Beamforming Networks for Phased Array Antennas Using Advanced MMCM Technology”, 1996 IEEE MTT-S International Microwave Symposium Digest, San Francisco, Jun. 17-21, 1996,vol. 1, Jun. 17, 1996, pp. 79-82, XP000704868.
P. Monfraix et al, “3D Microwave Modules for Space Applications”, 1998 IEEE MTT-S International Microwave Symposium Digest, vol. 3, Jun. 7-12, 1998, pp. 1289-1292, XP002106340.
George Sëbastien
Ulian Patrice
Alcatel
Ho Tan
Sughrue Mion Zinn Macpeak & Seas, PLLC
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