Amplifiers – With traveling wave-type tube
Reexamination Certificate
2000-07-13
2004-08-24
Pascal, Robert (Department: 2817)
Amplifiers
With traveling wave-type tube
C330S149000
Reexamination Certificate
active
06781454
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to communication satellites, and more particularly, to a traveling wave tube circuit for communication satellites.
BACKGROUND ART
Traveling wave tube amplifiers, or traveling wave tubes as they are sometimes referred to, commonly consist of a vacuum tube RF high power amplifier. In most applications for space systems, the high power traveling wave tube amplifier is positioned some distance away from a predistortion linearizer and electronic power conditioner due to the differing operating temperature ranges of these devices. Commonly, the linearizer and power conditioner use solid state components and therefore require a lower operating temperature than the traveling wave tube amplifier. Commonly, an RF interconnecting cable is used to couple the traveling wave tube amplifier and the RF amplifiers and predistortion network. Such a device is shown in prior art
FIG. 1
having an RF input
10
coupled to an RF amplifier
12
which in turn is coupled in series with a predistortion network
14
. The predistortion network
14
is coupled to a second RF amplifier
16
. The second RF amplifier
16
is coupled to the traveling wave tube amplifier
18
by an RF connecting cable
20
. The RF amplifier
12
, predistortion network
14
and RF amplifier
16
are located in a low temperature zone
22
. The traveling wave tube
18
is positioned in a high temperature zone
24
.
One problem with such a design is that the RF connecting cable
20
must be accounted for when performing an RF alignment of the linearizer with the traveling wave tube amplifier
18
. When the alignment is completed with a specific cable length, any changes to the cable length may change the characteristics of the circuit and therefore the alignment process needs to be repeated.
Another drawback to the system is that the predistortion network is typically comprised of field effect transistors (FETs). These devices have limited operating range for reliable operation.
It would therefore be desirable to provide a traveling wave tube amplifier and predistortion network circuit integrated as a single unit that does not require alignment if the cable length is changed.
SUMMARY OF THE INVENTION
It would therefore be desirable to provide an improved traveling wave tube amplifier circuit that allows design flexibility for the spacecraft. It is a further object of the invention to provide a passive linearizer capable of operating at high temperatures to eliminate the effect of the RF connecting cable on the design of the circuit.
In one aspect of the invention, a traveling wave tube amplifier assembly has a traveling wave tube, a predistortion network coupled to the traveling wave tube and physically coupled to the traveling wave tube. An amplifier is separated from the traveling wave tube and the predistortion network by a connecting cable coupled to the amplifier and the predistortion network. In a preferred embodiment of the invention, the predistortion network and traveling wave tube are located in a high temperature zone and the RF amplifier is located in a lower temperature zone than the high temperature zone.
One advantage of the invention is that the cable length may be changed to accommodate various designs process without having to perform another alignment process.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.
REFERENCES:
patent: 4701717 (1987-10-01), Radermacher et al.
patent: 5015965 (1991-05-01), Katz et al.
patent: 5291148 (1994-03-01), Reisner et al.
patent: 5430568 (1995-07-01), Little et al.
patent: 5523716 (1996-06-01), Grebliunas et al.
patent: 5617059 (1997-04-01), Eggleston
patent: 5703531 (1997-12-01), Vaughn et al.
patent: 5939920 (1999-08-01), Hiraizumi
patent: 5966049 (1999-10-01), Yuen et al.
patent: 6255908 (2001-07-01), Ghannouchi et al.
Gudmestad Terje
Hughes Electronics Corporation
Nguyen Khanh Van
Pascal Robert
LandOfFree
Linearized traveling wave tube circuit with pre-distortion... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Linearized traveling wave tube circuit with pre-distortion..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Linearized traveling wave tube circuit with pre-distortion... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3340912