Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
1999-05-24
2001-10-02
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C333S137000
Reexamination Certificate
active
06297714
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for transmission and/or reception of signals.
BACKGROUND OF THE INVENTION
Telecommunication services of the wire-free interactive type are developing rapidly. These services relate to telephony, facsimile transmission, television, in particular digital television, the so-called “multimedia” sector and the internet network. The equipment for these mass-market services has to be made available at a reasonable cost. This is so, in particular, as regards the user's receiver/transmitter which has to communicate with a server, most often via a telecommunication satellite, or in the scope of an MMDS (multi-point multi-channel distribution system), LMDS (local multi-point distribution system) or MVDS (multi-point video distribution system). These communication methods generally use the microwave range. For example, in the scope of the MMDS, frequency bands of the order of 40 GHz are used.
For these frequency ranges, a waveguide receiver and a wavelength transmitter can be used, the two waveguides being separate.
FIG. 1
represents a diagram of a device
1
for the transmission/reception of signals, in general located outside a dwelling (not shown). This device
1
comprises, on the one hand, a reception antenna
2
, connected by a reception path
3
to a unit
4
for conversion to intermediate frequency and, on the other hand, a transmission antenna
5
, connected by a transmission path
6
to a unit
7
for frequency conversion to a higher frequency. The two units
4
,
7
are connected by a coaxial cable
80
to a set inside the dwelling. Each unit
4
,
7
respectively comprises a mixer
4
1
,
7
1
connected to a local oscillator
4
2
,
7
2
. The transmission antenna makes it possible to employ a return path to the transmitter.
The device which has just been described has the disadvantage of requiring, in particular, two local oscillators in the conversion units
4
,
7
of the outside set, one for reception and the other for transmission.
SUMMARY OF THE INVENTION
The object of the invention is to avoid the drawbacks of the prior art cited.
It relates to a device for transmission and/or reception of signals, comprising:
a first waveguide for the operation in a first frequency band and the operation in a second frequency band,
a first frequency conversion circuit and a second frequency conversion circuit coupled with the first waveguide for the frequency conversion respectively of a first signal and of a second signal,
a local oscillator connected to one of the two circuits, characterized in that said device comprises further:
a second waveguide for the transmission of a signal of the local oscillator to the other of the two circuits for its use in the frequency conversion for the second circuit.
In this way, the invention avoids at least the duplication of certain components, in the case in point the local oscillator. The production cost is thus reduced by this. Furthermore, the microstrip links connecting the local oscillator to the circuit opposite would generate injection losses, causing degradation of the signal conveyed along these lines, whereas guided propagation of the signals minimizes these losses over the length of the waveguide, further economizing on the use of an amplifier.
If a single polarization is transmitted, the said first guide may be of parallelepipedal shape. According to a variant of the invention, the guide is cylindrical.
In order to maximize the energy delivered at the junctions between the second waveguide and the microstrip lines, the said second guide is closed at its ends by a quarter-wave cavity of length equal to one quarter of the guided wavelength of the transmitted signal. These quarter-wave cavities function as open circuits in the planes of the transmission and reception circuits for the waves to be delivered.
According to one embodiment, said first and second waveguides are interdependent with a same support.
According to one embodiment, said the first and second circuits are arranged on a first and a second microstrip circuit boards.
According to one embodiment, said coupling of the local oscillator connected to the one of the two circuits with the second waveguide and the coupling of this second waveguide with the other of the two circuits are realized by means of probes.
According to one embodiment, one of the frequency bands is used for the transmission of signals, and the second frequency band is used for the reception of signals.
According to one embodiment, the microstrip circuit boards cut the first waveguide in cross sections of said first guide.
According to one embodiment, the circuit board used for transmission is arranged upstream of the said circuit board used for reception in the signal reception direction of the device.
According to one embodiment, the circuit board used for transmission is arranged upstream of the said circuit board used for reception in the signal reception direction of the device.
According to one embodiment, the first waveguide comprises filtering means of type comprising a filter with iris cavity, a filter with screw cavity or a filter comprising at least two resonant cavities connected transversely to the body of the guide by coupling with irises, said filtering means being arranged in such a way that the waves transmitted by the first probe are attenuated enough on the second probe side in order not to interfere with the waves received at this second probe.
REFERENCES:
patent: 4333076 (1982-06-01), Cachier
patent: 4777654 (1988-10-01), Conti
patent: 4853657 (1989-08-01), Cruchon et al.
patent: 5384557 (1995-01-01), Yoshida et al.
patent: 5926129 (1999-07-01), Ephgrave et al.
patent: 0398688A (1990-11-01), None
patent: 0552944A (1993-07-01), None
Patent Abstracts of Japan, vol. 18, No. 646 (E-1641), Dec. 8, 1994-&JP 06 252609A (Toshiba Corp), Sep. 9, 1994.
Patent Abstracts of Japan, vol. 97, No. 12, Dec. 25, 1997 & JP 09 219664A (NEC Corp), Aug. 19, 1997.
French search report dated Feb. 12, 1999.
Guo Chaoying
Hirtzlin Patrice
Howson Christopher
Akiyama Kuniyuki
Pascal Robert
Summons Barbara
Thomson Licensing S.A.
Tripoli Joseph S.
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