Wave transmission lines and networks – Plural channel systems – Having branched circuits
Patent
1997-01-07
1998-06-30
Gensler, Paul
Wave transmission lines and networks
Plural channel systems
Having branched circuits
333115, 333116, 333 33, H01P 504
Patent
active
057740267
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the field of transmission of signals between apparatus for circuits having different physical and electrical characteristics and requiring matching, and has for its object a coupling and matching circuit adapted to interconnect a low impedance output device and a very high impedance input device, for the transmission of high frequency and ultra-high frequency signals.
Although the invention is not limited to use with specific types of devices to be connected, it will be described hereinafter more particularly in the framework of application to a scanning slot camera.
Scanning slot cameras operating by synchronous scanning, also called "synchroscan", are often used to observe recurrent luminous phenomena which repeat with a constant frequency f.sub.0 of the order of about 100 megahertz (MHz).
This manner of operation is very interesting because it has different important advantages, namely: screen results from the accumulation of a large number of elemental traces, tube is sinusoidal and, because of this, its elaboration is easier than that of a linear trace, signal.
The operating diagram of such a camera 1 and of its synchronization loop 2 for its sweeping circuit 2' is reproduced in FIG. 1 of the accompanying drawings.
A portion of the luminous signal to be analyzed is converted by a rapid photodiode 3 and a voltage of frequency l/f.sub.0 which is shaped, then frequency multiplied by a matched circuit 4.
The harmonic of quality n is then isolated by a pass-band filter 5, supplied to a power amplifier 6 and, finally, supplied to the deflection plates 7, 7' of the sweeping circuit 2' by means of a matching unit 8, in this case in the form of a selective impedance transformer whose purpose is to optimize the power transfer between the amplifier 6 and the sweeping circuit 2'.
The voltage difference V(t) developed across the terminals of the deflection plates 7, 7' is thus of the form:
For usual deviation sensitivities (<300 V/cm) and for a fairly high amplitude V.sub.0 (.about.1 kV) it can be considered that the deflection of the electron beam in a field of radius 1.5 cm is a quasi-linear function of time.
At present, the temporal resolution of so-called "synchroscan" cameras is principally determined by the dynamic spatial resolution of the tube (.about.60 .mu.m) divided by the speed of deflection.
This latter being proportional to the temporal derivative of voltage V(t), it is evident that it is of interest to optimize the product nV.sub.0.
In general, the amplitude V.sub.0 is regulated in such a manner that the power dissipated in the tube will be adjacent the maximum permissible (.about.5 W). As to the parameter n, it is often taken to be equal to unity (nf.sub.0 .about.100 MHz) because the production of the matching transformer 8 is simpler: the temporal resolution is then about 1.5 ps.
In practice, the scanning frequency is limited upwardly by the resonance of the tube which is ordinarily between 500 and 600 MHz. It follows that its maximum value corresponds to: n=5, for which value the theoretical resolution is less than 500 fs. However, in this frequency range, the transformers of magnetic type employed at 100 MHZ are unusable and cannot be matched to the level of their secondary, because of the self-inductance of this latter.
There is known from U.S. Pat. No. 3,166,723 a bidirectional coupling device for the transmission of high frequency and ultra high frequency signals constituted by two line sections having portions arranged in parallel and weakly coupled with each other and by a ground plane disposed parallel to the secondary line portion and adapted to form a part of a shielding envelope surrounding said circuit.
This known device also comprises a device for adjusting the degree of coupling between the primary and the secondary by bringing the primary and secondary conductors toward or away from each other in the coupling region.
However, this coupling device does not permit providing an adaptation of impedance between a circuit connected to the primary and a
REFERENCES:
patent: 3166723 (1965-01-01), Bock et al.
patent: 3363201 (1968-01-01), Isaacson
patent: 3560885 (1971-02-01), Chao
patent: 4754241 (1988-06-01), Spinner
Bryukhnevich et al., "Matching of the Shutter and Deflecting Systems of a PIM-3 Image Converter with a Control Circuit", Instruments and Experimental Techniques, vol. 15, No. 6, Dec. 1972, New York, pp. 1798-1802.
Cunin Bernard
Geist Paul
Martz Alphonse
Miehe Joseph-Albert
Communaute Europeenne
Gensler Paul
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