Wave transmission lines and networks – Long line elements and components – Switch
Reexamination Certificate
1999-09-21
2001-10-30
Bettendorf, Justin P. (Department: 2817)
Wave transmission lines and networks
Long line elements and components
Switch
C200S181000
Reexamination Certificate
active
06310526
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to miniature electromagnetic switches for microwave systems. More specifically, the invention relates to a miniature double-throw electromagnetic microwave switch capable of operation in three different states.
2. Description of the Prior Art
Switches are a basic building block of communication electronics and can find many applications in telecommunications. They are widely used for telecommunications applications such as signal routing, redundancy switching, impedance matching networks and adjustable gain amplifiers. Mechanical relay, PIN diode and FET are the common microwave switches. Mechanical relays offer the benefits of low insertion loss, large off-state isolation, and high power handling capabilities. However, they consume a lot of power and are bulky, heavy and slow. Semiconductor switches such as PIN diode and FET provide much faster switching speed and smaller size and weight but are inferior in insertion loss, isolation and power handling capabilities than mechanical relays.
Microwave switches providing the advantageous properties of both the mechanical relay and semiconductor switch are then highly desirable, especially for space, airborne and mobile telecommunications applications. Micromachining technologies promise to enable the fabrication of such switches, i.e., switches with the high microwave performance of mechanical switches but also with the small size, weight and power consumption of semiconductor switches. Furthermore, conventional microelectronics fabrication processes are usually used for micromachining, making the integration of such miniature switches with other active electronics possible.
In U.S. patent application Ser. No. 09/131,594 entitled ‘Miniature Electromagnetic Microwave Switches and Switch Arrays’ filed on Aug. 10, 1998 by the same inventors, now U.S. Pat. No. 6,016,092 single-throw micro electromagnetic switches in a coplanar waveguide, microstrip or stripline form were described. A double-throw switch in a stripline form was also described. In this invention, miniature double-throw electromagnetic switches on dielectric substrates in a microstrip form and with controlled magnetization are disclosed. These double-throw switches are useful in many applications for effective switching and routing of microwave signals.
SUMMARY OF THE INVENTION
The present invention provides multilayer thin film electromagnetic coil, miniature double-throw switches and switch arrays for microwave communications.
In one embodiment of this invention, a multilayer thin film electromagnetic coil where the magnetic fields induced in all layers of the coils aligned in the same direction is disclosed. This multilayer thin film electromagnetic coil may be fabricated by IC technology. Using the multilayer thin film electromagnetic coil, strong magnetic field can be induced with reduced power consumption.
In another embodiment, double-throw miniature electromagnetic microwave switches for microstrip transmission lines are disclosed. The switches are created on a dielectric substrate by a micromachining process or an evaporation process. According to this invention, this structure consists of a dielectric substrate, an input transmission line having a first cantilever, a first output transmission line, a second output transmission line having a second cantilever, and a miniature electromagnetic coil. A layer of permanent magnetic material is deposited on a portion of the first cantilever. The first cantilever is in its normal position when no current is applied to the miniature electromagnetic coil. When a positive current is applied to the miniature coil, an electromagnetic force is generated to attract the first cantilever to a down position, so that it is in contact with the first output transmission line. When a negative current is applied to the miniature electromagnetic coil, a reversed electromagnetic force is generated to push the first cantilever to an up position so that it is in contact with the second cantilever and, therefore, the second output transmission line.
In yet another embodiment, a double-throw switch is disclosed which consists of a dielectric substrate, an input transmission line having a first cantilever with a first permanent magnetic film and a second cantilever with a second permanent magnetic film, a first output transmission line, and a second output transmission. The magnetic polarizations of the first magnetic film and the second magnetic film are arranged in such a way that when a miniature electromagnetic coil is activated, the forces applied to the first cantilever will be opposite to that to the second cantilever under the same electromagnetic field induced by the miniature electromagnetic coil. Therefore, the input transmission line will make contact to either one of the two output transmission lines, depending on the current direction applied to the coil.
The single-pole, single-throw miniature electromagnetic microwave switches described in U.S. patent application Ser. No. 09/131,594, entitled ‘Miniature Electromagnetic Microwave Switches and Switch Arrays’ filed on Aug. 10, 1998 by the inventors of this application, have many advantages such as high performances, small requirements of resources (size, weight and power consumption) and possible integration with other integrated electronics. In many applications, however, double-throw or multiple-throw switches are required for efficient switching or routing of microwave signals. The present invention allows the fabrication of miniature electromagnetic double-throw or multiple-throw switches based on the micromachining technologies. Multiple cantilevers in a double-throw switch can be controlled by a single electromagnetic coil to reduce size, complexity and power consumption of the switch. For a multiple-throw switch, more than one electromagnetic coil may be needed to control all the cantilevers. It should be noted that only double-throw switches are described in the present invention; however, multiplethrow and/or multiple-pole switches can be easily built based on the present invention with only small modification to the switch structure.
REFERENCES:
patent: 5578976 (1996-11-01), Yao
patent: 5880921 (1999-03-01), Tham
patent: 6016092 (2000-01-01), Qui
patent: 6049702 (2000-04-01), Tham
patent: 6160230 (2000-12-01), McMillian
Qiu Cindy Xing
Shih Yi-Chi
Yip Lap-Sum
Bettendorf Justin P.
Takaoka Dean
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