Communications: directive radio wave systems and devices (e.g. – With particular circuit
Reexamination Certificate
2003-02-13
2004-06-29
Sotomayor, John B. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
With particular circuit
C342S028000
Reexamination Certificate
active
06756936
ABSTRACT:
NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION
A portion of the material in this patent document is subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise reserves all copyright rights whatsoever. The copyright owner does not hereby waive any of its rights to have this patent document maintained in secrecy, including without limitation its rights pursuant to 37 C.F.R. § 1.14.
A portion of the material in this patent document is also subject to protection under the maskwork registration laws of the United States and of other countries. The owner of the maskwork rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise reserves all maskwork rights whatsoever. The maskwork owner does not hereby waive any of its rights to have this patent document maintained in secrecy, including without limitation its rights pursuant to 37 C.F.R. § 1.14.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to microwave transceivers used in motion detectors, such as Doppler shifted radar sensors used for detecting a moving target in the security industry, and more particularly to a planar transceiver which employs a chip on board design where all components can be surface mounted.
2. Description of Related Art
Microwave transceivers have been used in many applications, such as traffic surveillance radar systems, point-to-point communications systems, and intrusion detection systems. A microwave transceiver typically generates microwave radiation by means of a waveguide cavity oscillator or a transistor oscillator. The microwave radiation is then radiated into free space by means of a waveguide horn antenna or a microstrip patch antenna. A transistor oscillator using, for example, a field effect or a bipolar transistor, together with a dielectric resonator to stabilize its performance, is normally used for frequencies below approximately 14 GHz. Most commonly a packaged FET or Schottky device is used and soldered into the circuit. Examples of patents describing this type of configuration are U.S. Pat. Nos. 4,630,003, 4,445,097, 5,371,509, and 5,583,523, each of which is incorporated herein by reference.
Various approaches have been taken in the construction of these lower frequency transceivers. For example, GB 2 253 108 A, incorporated herein by reference, shows a multilayer construction where the microwave components and the patch antennas are on separate circuit boards. The microwave circuit board has a component side and a ground plane side, and the antennas are coupled to the microwave circuitry by means of microstrips on the antenna board that are orthogonal to slots in the ground plane that are resonant at the oscillator frequency. This transceiver configuration also uses a dielectric resonator in the oscillator. Another example is U.S. Pat. No. 6,064,276, incorporated herein by reference, which uses a similar approach but has an extra Schottky device for frequency tuning of the oscillator. GB 2 243 495 A, incorporated herein by reference, describes a dielectric resonant oscillator of the type used in the foregoing two patents.
At higher microwave frequencies, such as 24 GHz and above, a beam-lead or Flip-chip Schottky diode is normally used in a microstrip mixer circuit. These diodes, however, are fragile and require a hard plate to support the microstrip substrate. Because of this requirement, high frequency microstrip circuits generally have only one substrate layer as, for example, shown in U.S. Pat. No. 5,832,376 incorporated herein by reference.
Waveguide cavity oscillators are preferred for use at these higher microwave frequencies because the performance of packaged transistors declines at higher frequencies. A Gunn diode (for the oscillator) and Schottky diode) for the mixer are commonly found in waveguide transceivers. Such waveguide transceivers typically include an oscillator, a circulator, a mixer, an antenna, and a waveguide to antenna transition. As shown in U.S. Pat. No. 6,008,750, incorporated herein by reference, a waveguide transceiver has been combined with a microstrip patch antenna to avoid this difficulty. However, because Gunn and Schottky diodes are used in the transceiver, it suffers from the disadvantage of requiring a relatively large amount of manual assembly, and the transceiver is bulky, heavy and costly. Also, the current consumption of a Gunn diode is typically six to eight times higher than that of a low phase noise GaAs MESFET oscillator, thus rendering a waveguide transceiver impractical as a wireless sensor.
Therefore, there is a need for a high frequency microwave transceiver for use as a wireless sensor that is small, lightweight, low cost and which addresses the foregoing and other deficiencies of waveguide transceivers.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to a novel transceiver design for use in motion sensors, which is of a smaller size, has a lower cost, and has lower current consumption and better performance than conventional transceivers. The invention is suitable for automatic assembly and can be used in wireless security applications.
By way of example, and not of limitation, the foregoing needs are met by a microwave transceiver design where, according to an aspect of the invention, the oscillator comprises a surface mounted FET chip and the mixer comprises a pair of surface mounted Schottky chips, all of which are wire bonded to microstrip circuitry. As a result, a 24 GHz transceiver module according to the invention is of a smaller size, lower cost, lighter weight and more suitable for mass production than conventional transceiver shown in FIG.
4
. Beneficially, a microwave transceiver according to a further aspect of the invention is a substantially planar transceiver.
In one embodiment of the invention, the transceiver is a module that includes a soft multilayer printed circuit board made, for example, from a Teflon®-based material. A patch-type transmit antenna and a patch-type receive antenna are patterned on one side of the multilayer circuit board, while the other circuitry is located on the other side of the multilayer circuit board.
In one embodiment, a microwave circuit board comprising a microstrip oscillator circuit and a microstrip mixer circuit is superimposed over an antenna circuit board comprising a transmit antenna and a receive antenna with a ground plane layer in-between. Each antenna has a respective microstrip that is aligned with an associated microstrip on the microwave circuit board, and the ground plane layer has, for each antenna, a respective slot to provide coupling between the antenna microstrip and the associated microstrip on the microwave circuit board.
According to an aspect of the invention, the oscillator circuit uses a wire bonded surface mounted transistor chip and does not require a dielectric resonator. According to another aspect of the invention, the mixer circuit comprises a balanced mixer that uses a pair of wire bonded surface mounted diode chips. In one embodiment, the transistor chip comprises a field effect transistor. In another embodiment, the mixer diode chip comprises a Schottky diode.
In accordance with another aspect of the invention, the transceiver assembly is disposed within the cavity of a housing in which the transceiver assembly is hermetically sealed.
In one embodiment, the output signal from the local oscillator is coupled through a direct current (DC) block to the input of a power divider. A portion of the local oscillator signal is coupled to the transmit antenna through a first output of the power divider which is coupled to the transmit antenna throu
Honeywell International , Inc.
O'Banion John P.
Sotomayor John B.
LandOfFree
Microwave planar motion sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Microwave planar motion sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microwave planar motion sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3315120