Telecommunications – Receiver or analog modulated signal frequency converter – With wave collector
Reexamination Certificate
1998-03-31
2001-05-08
Nguyen, Lee (Department: 2683)
Telecommunications
Receiver or analog modulated signal frequency converter
With wave collector
C455S080000, C455S272000, C342S027000, C342S028000
Reexamination Certificate
active
06229999
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a receiver system for the reception of a series of ultrashort pulsed electromagnetic signals, comprising at least one antenna, connection means, at least one sample switch, at least one sample capacitor and an amplifier circuit.
2. Discussion of the Background
Such a receiver system is known from the U.S. Pat. No. specification U.S. Pat. No. 5,375,200. The receiver system described in this patent specification constitutes part of a low-budget radar system in which a radar transmitter, an antenna and the receiver system are implemented as an integrated system, the distance between the antenna and the receiver being practically negligible. For more sophisticated applications it may be advantageous to maintain a certain distance between the receiver and the antenna. In case of ship-mounted applications, the receiver is preferably housed below deck, whereas the antenna naturally requires an elevated position. In this situation, received ultrashort signals would have to be passed, for instance via a cable, from the antenna to the receiver. This is undesirable, because pulse attenuation and pulse widening inevitably occur during this transport, with the added risk of electromagnetic interference.
SUMMARY OF THE INVENTION
The receiver system according to the invention does not have this drawback and is characterized in that the sample switch is connected between the at least one antenna and the at least one sample capacitor, the connection means constituting a galvanic connection between the at least one sample capacitor and the amplifier circuit. By thus integrating the sample switch with the antenna, the maximum feasible range resolution can be realized with the transport of relatively low-frequency signals.
An advantageous embodiment of the receiver system according to the invention is characterized in that the at least one sample switch comprises a switching diode and that a galvanic control input is provided for the bringing into conduction, by means of an electric sample pulse, of the at least one switching diode for the sampling of an antenna signal.
Because the electric sample pulse, too, is ultrashort, it may be difficult to transport this pulse over a relatively long distance. A further advantageous embodiment is thereto characterized in that the switching diode is provided with an optical control input for the bringing into conduction, by means of an optical sample pulse, of the at least one switching diode for the sampling of an antenna signal. Optical sample pulses are known for their capacity to be transported over long distances without any substantial pulse widening or pulse attenuation, the transport being moreover impervious to electromagnetic interference.
An extremely advantageous embodiment of the receiver system according to the invention is characterized in that the antenna comprises at least one dipole antenna with two terminals, each of which is connected, via a switching diode, to a sample capacitor. Apart from featuring a satisfactory common mode interference suppression, this embodiment has the advantage that the antenna diagram is known and reproducible. In this embodiment the connection means comprise at least two galvanic connections, which connect both sample capacitors to the amplifier circuit. As is customary, these connection means are incorporated in a preferably common earthed housing in order to suppress electromagnetic interference.
A further advantageous embodiment of the invention is characterized in that the connection means comprise at least two galvanic connections and that the sample capacitors are both connected, via a resistor and a galvanic connection, to the amplifier circuit. The integration of the resistors in the antenna yields an antenna module that produces a current that is proportional to the field intensity measured by the antenna during the presence of the sample pulse and whose output current can easily be combined with output currents of other modules. This is of particular relevance if an antenna diagram with an enhanced directivity is to be realized. With a view to increasing the directivity, a number of dipoles can be combined in a manner known in the art, although this requires expensive RF combination systems. An extremely advantageous embodiment of the invention is, however, characterized in that the antenna comprises an array of dipole antennas in which each dipole is provided with a first switching diode and a second switching diode, connected to a first sample capacitor and a second sample capacitor respectively, and in which the connection means comprise a first galvanic connection to which the first sample capacitors are connected, each via a resistor, and a second galvanic connection to which the second sample capacitors are connected, each via a resistor, the first and the second galvanic connection being connected to the amplifier circuit. Thus, the amplifier circuit can add the current generated per dipole antenna in order to realize the desired level of directivity.
REFERENCES:
patent: 5361070 (1994-11-01), McEwan
patent: 5428830 (1995-06-01), Zerod et al.
patent: 5457394 (1995-10-01), McEwan
patent: 5521600 (1996-05-01), McEwan
patent: 5640168 (1997-06-01), Heger et al.
patent: 5966090 (1999-10-01), McEwan
Hollandse Signaalapparaten B.V.
Nguyen Lee
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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