Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Reexamination Certificate
1999-06-14
2001-08-14
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
C324S637000
Reexamination Certificate
active
06275045
ABSTRACT:
DESCRIPTION
This invention relates to a microwave emitter-receiver device.
It may be used for miscellaneous applications and particularly to monitor physical or chemical changes in a surrounding environment or to detect when an object passes. It is known that radiation passing through this environment is subject to disturbances that depend on its composition; the emitter then sends radiation in the form of a defined signal and the measurement consists of analyzing the signal received by the receiver after being modified by the medium through which it passes. These examination processes may be used continuously for applications in which risk areas are monitored and when carrying out tests; disturbances to environments through which radiation passes may be solid objects, or also and very frequently gasses, atmospheric pollutants, leakage gases, fire and firing plums. These devices may be used with measurement benches or with alarm beacons.
Infrared radiation, visible light and ultraviolet radiation have already been used with this type of device, but they have the disadvantage that they become inoperative under bad conditions; surrounding thermal radiation sources also produce infrared radiation that disturbs the measurements, and rain absorbs light radiation. These types of disturbances prevent detectors that analyze the received signal from seeing the signal.
Therefore it is preferred to use other wave types. Some systems include emission of a carrier wave within a restricted frequency range, which has the disadvantage that it only enables reduced observations. It is usually preferable to supply a wave stream extended over a wide frequency range, which imposes the use of a brief pulse so that a large proportion of the signal emitted is located in high frequencies. A recent illustration of a radar system with ultra-short pulses and a wide frequency range is given in the article by W. M. Boerner and J. S. Verdi “Polarimetric UWB Radar/Sensing & Imaging” at the UWB-SP-2 Conference in Albuquerque in May 1996. Systems with electronic, opto-electronic or mixed triggering of the wave stream have been proposed.
The invention relates to an emitter-receiver device that can be used in high frequency spectroscopy (of the order of a gigahertz or a terahertz) and which has a particularly easy and compact design. It comprises an emitter and a receiver of electromagnetic waves with an antenna. The wave stream is triggered opto-electronically, using a light pulse generator system that illuminates a photo-conducting layer on which the emitter antenna is deposited or printed; a short circuit is created in the antenna which becomes active and emits the wave stream. Light pulses are also transmitted to the receiver, the receiver antenna being laid out in the same way on a photo-conducting layer, and also activates this receiving antenna so that it can collect the wave stream after it has passed through the environment being studied and then transmit it to means of recording or using the stream. The receiving antenna usually needs to be activated slightly after the emitting antenna to synchronize the process by absorbing the time necessary for the wave stream to pass between the antennas. A prior opto-electronic device that can be used for the same applications is described in U.S. Pat. No. 4,855,749 A, but it is not the same as the invention and its performances are much lower, as will be seen in more detail later.
All elements of the device may be placed on a single support board or on a small number of such boards, and a single electricity power supply is possible both for the emitting antenna and for control, usage and recording means, and for the light pulse generation means which could be a laser. In this case, its operation may be made discontinuous by an opto-electronic gate that chops its light radiation or by an element that varies the impedance of optical lines through which its light passes.
In its most general form, the invention relates to a wave emitter-receiver device to examine a medium through which the waves pass, comprising an emitter with an antenna and a receiver with an antenna, a wave generation device connected to the emitter, and a signal reception and usage device connected to the receiver; the antennas are formed of distinct portions and are laid out on a photo-conducting layer, the wave generation device comprises an electricity power supply initiating a potential difference between the portions of the emitter antenna, and the wave generation devices and signal reception and usage devices comprise means of supplying light pulses to the photo-conducting layers between the portions of the antennas; all this is similar to the device in U.S. Pat. No. 4,855,749, but the invention also involves the use of micro-lasers fixed on photo-conducting layers in order to form integrated receiver and emitter elements, whereas in the previous patent excitation is obtained by ordinary lasers which are large and difficult to adjust correctly. Note that with this type of opto-electronic device it is difficult to suitably transmit a wave stream due to its intensity and its frequency band. However the invention offers a device composed of emitter and receiver elements for which the adjustment will not change, due to the use of micro-lasers that are perfectly compatible with the stacks of photo-conducting layers. Another advantage is that these emitter and receiver elements may be moved without difficulty if the tests are to be carried out in different locations.
The invention will now be described in more detail using the following figures attached for illustrative and non-restrictive purposes, in order to better understand and describe other characteristics and qualities:
FIG. 1
is an overview of an embodiment of the invention;
FIG. 2
illustrates some details of another embodiment of the invention;
FIG. 3
is a view of another embodiment of the invention;
FIGS. 4 and 5
illustrate emitted and received wave streams;
FIGS. 6 and 7
illustrate use of these wave streams for measurement;
and
FIG. 8
illustrates a variant of FIG.
1
.
REFERENCES:
patent: 4855749 (1989-08-01), DeFonzo
patent: 5056111 (1991-10-01), Duling, III et al.
patent: 5128621 (1992-07-01), Berthaud et al.
patent: 5719664 (1998-02-01), Besesty et al.
patent: 6087991 (2000-07-01), Kustas
patent: 0706063 (1996-04-01), None
patent: 0727671 (1996-08-01), None
Katzenellenbogen et al, Efficient generation of 380 fs pulses of THz radiation by ultra fast laser pulse excitation of a biased metal-semiconductor interface, Applied Physics Letters, vol. 58, No. 3 Jan. 21, 1991, pp. 222-224.
Brown Glenn W.
Commissariat A l'Energie Atomique
Hayes Soloway Hennessey Grossman & Hage PC
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