Frequency translator

A planar balun coupled frequency translator (upconverter or downconverter, is illustrated in various configurations for providing both full-wave and half-wave signal frequency conversion. As illustrated, each of the circuits uses microstrip and strip transmission line construction techniques for cost effective construction. As designed, the carrier and signal frequency baluns are separately interfaced in sets rather than all being connected in series as in the prior art.

THE INVENTION 
The present invention is generally concerned with electronics and more 
specifically concerned with frequency converters. Even more specifically, 
the present invention deals with microstrip frequency converters using 
cost effective design construction techniques. 
Prior art approaches to frequency translators have used a series connection 
of the secondary windings of the baluns involved therewith. Such an 
example is found in a Mouw U.S. Pat. No. 3,818,385 which issued June 18, 
1974 to Aertech of Sunnyvale, Calif. The equivalent circuit in this patent 
showing such a connection is as an example FIG. 5. Another example of such 
a type of connection is shown in my copending patent application Serial 
No. 889,171 filed Mar. 23, 1978, now U.S. Pat. No. 4,186,352, issued Jan. 
29, 1980, and assigned to the same assignee as the present invention. This 
invention used similar planar balun microstrip and stripline transmission 
line construction techniques as the present invention but did not have the 
same approach to isolation and did not achieve mutual isolation in the 
same manner as the present invention between balun secondaries for the 
signal and carrier frequency portions of the converter. 
While my other invention referenced above has performed to expectations, 
there have been instances where it would be desirable to have more 
versatility over a broad frequency range in the placement of the 
input-output ports. In other words, it is sometimes desirable to have all 
of the ports on one side of a board and it is also desirable at times to 
change these around. The present invention offers a great deal of 
flexibility in this respect while still using similar design criteria in 
designing the structural characteristics of the baluns involved. 
It is therefore, an object of the present invention to provide an improved 
frequency translator.

DETAILED DESCRIPTION 
In FIG. 1, a ground plane 10 completely encloses on all four sides a 
plurality of conductors, balun secondary circuit paths or signal coupling 
means 12, 14, 16, 18, 20, 22, 24 and 26, each extending from the ground 
plane 10, connected thereto and in the same planar surface as the ground 
plane. Signal coupling means 12 is coupled to a transmission line signal 
conductor means or balun primary circuit path 28 as are the circuit paths 
14, 16 and 18. Transmission line conductive means 28 receives the signal 
frequencies (f.sub.s) which are supplied to the translator of FIG. 1. 
Coupling means 20 is coupled to a carrier frequency (f.sub.c) transmission 
line conductive means or balun primary circuit path 30 as are circuit 
paths 22, 24 and 26. The end or terminal of each of the circuit paths 12 
through 26 which is furthest from the ground plane connection is 
additionally labeled with numbers 1 through 8 as illustrated. As shown, a 
conductive path 32 connects terminals 1 and 5 of circuit paths 12 and 22 
respectively. At the approximate center of this path is a terminal labeled 
A to which is connected a D1 diode 34. The other end of diode 34 is 
connected to a junction point 36 which receives IF or intermediate 
frequency signals. End 4 of circuit path 18 is connected to end 7 of 
circuit path 20 by a lead or conductive path 38 which has an intermediate 
terminal labeled D to which a D4 diode 40 is connected whose other lead is 
connected to junction point 36. End 2 of circuit path 16 is connected to 
end 6 of circuit path 26 via a signal conductor 42 which has an 
intermediate terminal B to which a D2 diode 44 is connected which has its 
other lead connected to junction point 36. Finally, a conductive path 46 
is used to connect end 3 of circuit path 14 to end 8 of circuit path 24. 
An intermediate point C is connected to one end of a diode D3 also 
designated as 48 which has its other lead connected to junction point 36. 
In actual fabrication of the device of FIG. 1, the ground plane 10 along 
with the signal coupling means would be applied to one side of a substrate 
or printed circuit board while the transmission line conductive means 28 
and 30 would be attached to the opposite side of the substrate. The 
substrate in most illustration herein has been eliminated for purposes of 
clarity. The odd looking arrangement for conductive path 46 is the result 
of trying to connect the terminals 3 and 8 where these paths must cross 
the other paths and thus plated through holes on the board are used to 
provide part of the connection on the opposite side of the board. The 
connections 42 and 32 also must bridge the conductive path 38. This can be 
accomplished by a variety of means including simple small bridges at each 
of the cross-overs or additional substrate material can be used to cover 
underlying paths. 
Regardless of the method used, it is desirable for most effective operation 
of the device that the connection points A, B, C and D of the diodes to 
the respective conductive paths be at appropriate points from the 
secondary circuit path pairs so that the relative phases of the signals at 
the diodes either be substantially in phase or substantially exactly out 
of phase. As illustrated for convenience, they are connected at 
approximate midpoints. 
As previously indicated, FIG. 2 is an equivalent circuit of the apparatus 
of FIG. 1. As illustrated, a signal frequency f.sub.s is applied to a 
coupling means illustrated as a transformer 50 having a primary winding 52 
and a pair of center tapped secondary windings 54 and 56. Additionally, a 
second coupling device represented as a transformer 58 has a primary 
winding 60 connected to a carrier signal f.sub.c and also has two center 
tapped secondary windings 62 and 64. The center tapped secondary windings 
have terminals labeled 1 through 8 which correspond with similar 
designations in FIG. 1. Additionally, diodes are shown in FIG. 2 having 
the same designations as used in FIG. 1. As will be obvious to anyone 
skilled in the art, the primary windings 52 and 60 represent the primary 
circuit or transmission line conductive means 28 and 30 while the 
secondary windings represent the secondary circuit or signal coupling 
means which are coupled to these transmission line conductor means. In 
other words, secondary winding 54 represents the coupling obtained by 
circuit paths 12 and 16 each of which has greater RF voltages as they 
extend away from the ground plane 10. The ground plane 10 is effectively a 
center tapped ground point of the same potential at the point of 
connection and thus is shown in FIG. 2 as a common connection to ground. 
The same comments apply to the remaining secondary windings. Finally, 
there are arrows used to explain relative voltage signal phases as further 
defined infra and in Table 3. A solid arrow is used to represent the 
signal frequency phases, a dash line arrow is used to represent the 
relative carrier frequency signals and the double line arrow is used to 
represent the phases of the intermediate or IF frequency signals. 
FIG. 4 is used to illustrate the low frequency lumped element equivalent 
circuit of a hybrid formed by the two baluns of the microstrip circuit of 
FIG. 1. In other words, the common diode load is not shown. As 
illustrated, a first balun 75 has a primary winding 77 and two secondary 
windings 79 and 81. A second balun represented by 83 has a primary winding 
85 and two secondary windings 87 and 89. The primary winding 77 receives a 
signal frequency signal and is alternatively labeled terminal I. The 
primary winding 85 is labeled terminal II and receives a carrier frequency 
signal. Each of the secondary windings is centertapped and connected to 
ground. As illustrated, the windings are connected in the same manner as 
shown in FIG. 2. In other words, winding 79 is connected in parallel with 
87 with effective dot connections together and has a load 91 connected 
between terminals A and B. Winding 81 is connected in parallel with 89 but 
connected (cross dot connections) in such a way as to cancel any signal 
frequency signals in core 83 and cancel carrier frequency signals in core 
75. Between junction points C and D a load 93 is connected in parallel 
with the two secondary windings. As will be observed, the carrier and 
signal frequency signals have the same polarity orientation in the load 91 
which is connected across terminal III while the carrier and signal 
frequency signals have opposing polarity orientations in load 93 connected 
across terminal IV. 
FIG. 5 illustrates substantially the same hybrid as illustrated in FIG. 4 
except that the two loads 91 and 93 have been split such that there are 
loads 91', 91", 93' and 93". Additionally, a common connection between 
equipotential points at the center of A-B and C-D load composite resistors 
91 and 93 are connected by a connection 95. Again, arrows are used to 
illustrate the relative phases at various points throughout the circuit. 
An observation of these arrows will illustrate that they are identical 
with that illustrated in FIG. 4. 
The double balanced frequency translator of FIG. 7 is similar in 
construction to that of FIG. 1. The only difference comprises four more 
diodes and a ferrite core used as an IF balun to alter the balanced output 
to an unbalanced output for interfacing with normally unbalanced IF signal 
sources or loads. Since the parts are for the most part identical, the 
same designation is used as used in FIG. 1 except that the designator is 
100 values higher. However, the diodes are newly numbered with diodes D1 
through D8 having the designations 150, 152, 154, 156, 158, 160, 162, and 
164. As illustrated, diodes D1, D3, D5 and D7 all have one end connected 
to a common junction 166 and the other ends connected respectively to A, 
B, C and D terminals. Likewise, diodes D2, D4, D6 and D8 are connected to 
a common junction 168 and at the other end connected respectively to 
terminals A, B, C and D. A ferrite core used as an IF balun 170 has a lead 
172 passing therethrough from junction 166 to the IF output while a 
further lead 174 passes therethrough from junction 168 to ground 110. 
The low frequency lumped element equivalent circuit of FIG. 8 illustrates 
the relative phase components of signals interacting in the frequency 
translator. As illustrated, a signal frequency is applied to a primary 
winding 185 of a balun generally designated as 187 having secondary 
windings 189 and 191. Carrier frequency signals are applied to a primary 
winding 193 of a balun generally designated as 195 having centertapped 
secondary windings 197 and 199. A first diode bridge 201 containing diodes 
D1 through D4 is connected as shown between termination points A and B 
while a second diode bridge 203 containing D5 through D8 are connected as 
shown between terminals C and D. As further illustrated, junctions F and H 
are tied together on bridges 201 and 203 to a dot side of winding 205 of a 
balun generally designated as 207 and having the other end of winding 205 
connected to junctions E and G on bridges 201 and 203. A secondary winding 
209 provides a connection to IF signal sources or loads depending upon 
whether the translator is used as an upconverter or a downconverter. 
FIG. 9 illustrates the relative phases of the various signals within the 
equivalent circuit in the same manner as illustrated previously in FIG. 3. 
FIG. 6 illustrates the relative phases of the signals within the hybrids of 
FIG. 4 and FIG. 5. Since this is substantially self-explanatory, no 
further mention will be made of this figure at this time. 
FIG. 10 illustrates another embodiment of the inventive concept where the 
signal frequency signals are input to a microstrip signal conductor 220 on 
one side of a ground plane structure 222 while carrier frequency signals 
are input to a bifurcated or forked transmission signal conductor 224 on 
the other side of ground plane 222. While normal practice would be to use 
separate substrates between each of the transmission signal conductors 220 
and 224 and ground plane 222, they can be merely suspended or spaced with 
any suitable dielectric. As shown, the transmission signal conductor 220 
interacts with signal coupling means 226, 228, 230 and 232 which are 
respectively connected at one end to ground plane 222 and at the other end 
are labeled respectively terminals 1, 3, 4 and 2 with alternate labels A, 
C, D and B. The forked transmission signal conductor 224 is split into two 
separate bifurcations, arms, tines legs 234 and 236 which as illustrated 
widen immediately prior to interacting with the secondary signal coupling 
means for the purpose of providing the proper impedance matching to signal 
sources or loads attached to conductor 224. As illustrated, the leg 236 
coacts with conductors 240 and 242 which are each connected at one end to 
ground plane 222 and at the other end are labeled terminals 7 and 8 
respectively and which as further illustrated are connected to junctions D 
and C respectively. Likewise, conductor 234 coacts with signal conductors 
244 and 246 which are each connected at one end to ground plane 222 and at 
the other end are labeled terminals 5 and 6 respectively and connected to 
terminals A and B. On the left side of FIG. 10 are shown diodes D1 through 
D4 or alternatively diodes 248, 250, 252 and 254 which are connected to 
the terminals A through D as shown. The other end of each of these diodes 
is connected to a common junction and to IF signal frequency terminal 260. 
The low frequency lumped element equivalent circuit of FIG. 11 which 
illustrates the equivalent circuit of FIG. 10 is very similar to previous 
equivalent circuits except that as shown the forked device with input lead 
224 acts as a power splitter 262 which supplies signals to separate 
primaries of a set of two single transformers 264 and 266. Thus, the 
canceling effect occurs back in the power splitter 262 rather than in the 
cores of the single baluns as previously occurred. Otherwise, the circuit 
is substantially identical with a dual balun 268 and half-wave diode pairs 
270 and 272. 
FIG. 12 illustrates a modification of FIG. 10 wherein the signal frequency 
and carrier frequency transmission signal conductors are both mounted on 
the same side of the board. Since these are so similar, each of the 
designators are the same as in FIG. 10 except that the designators are 100 
values higher. 
In FIG. 13, a signal frequency transmission signal primary conductor 400 is 
coupled to a plurality of signal coupling secondary means 402, 404, 406 
and 408 which are each connected at one end to a ground plane 410. At the 
other end of each of these signal coupling means 402 through 408, they are 
labeled respectively 1, 2, 3 and 4 and likewise A, B, C and D. A set of 
diodes, D1 through D4 are used to connect the points or terminals A 
through D to a common junction which is used as an IF output port 
generally designated as 412. A carrier frequency transmission signal 
conductor means 414 is coupled to a plurality of signal coupling means 
416, 418, 420 and 422. One end of each of these signal coupling means 416 
through 422 is connected to a ground plane 424 while the other end is 
labeled 5 through 8 as illustrated. The terminals 5 through 8 are 
connected to terminals 1 through 4 by electrical conductive means or wires 
426, 428, 430 and 432. 
FIG. 14 illustrates a container into which the frequency translator 
illustrated by FIG. 13 can be constructed. 
FIG. 15 shows a cross sectional view of FIG. 14 with the circuitry of FIG. 
13 inserted. In FIG. 15, in addition to an upper board 500 and a lower 
board 502, there is inserted some RF absorbing material 504. As 
illustrated, the connecting wires 506 and 508 (equivalent to wires 426 
through 432 of FIG. 13) hold the two boards 500 and 502 in place. The RF 
absorbing material can either be free floating, packed in between the 
boards 500 and 502 or supported by other means on the ends of the box in a 
manner not shown. As illustrated, the portions 510 and 512 are connectors 
for the carrier and signal frequency signals and there would, of course, 
be a connector for the IF frequency signals. To finalize the construction 
of this translator, there is also illustrated a cover 514 and a bottom 516 
which coact with the sides 518 to completely enclose the translator and 
shield it from extraneous interfering signals. 
Operation 
From reading my previously referenced copending application and from 
observing FIG. 1, it will be noted that a potential applied to a primary 
conductor, such as 28, is equally divided between the two secondary 
conductor pairs. The relative polarity is such that terminal 1 is negative 
with respect to terminal 2 and terminal 3 is negative with respect to 
terminal 4. Likewise, terminals 1 and 3 have no potential difference, one 
relative the other, and the same applies to terminals 2 and 4. Thus, if 
the primary conductor 28 and the secondary conductor pairs or coupling 
means are used alone as a microstrip dual balun (see FIG. 4) rather than 
as part of a frequency translator, a load may be connected between 
terminals 3 and 4 or between 1 and 2 in a conventional manner. A load also 
may be connected between terminals 2 and 3 and between 1 and 4 since these 
terminal pairs have the same potential difference as terminals 1-2 and 
3-4. This feature lends a degree of freedom in joining loads to the balun 
output, such that mutual isolation is maintained between the three 
principal signals when the baluns are arranged as shown in FIG. 1 for a 
frequency translator. The three principal signals would be (1) f.sub.s the 
input or output RF signal, (2) f.sub.c the local oscillator or pump 
carrier and (3) f.sub.IF the intermediate frequency carrier. 
As will be noted, the ends of the secondary windings in FIG. 2 are labeled 
with the same terminal numbers as found in FIG. 1 at the end of the 
secondary circuit paths furthest from ground plane 10. These numbers 
designate identical points in the two respresentations of the invention. 
The conduction path for the signal f.sub.s in the balun pairs 1-2 and 3-4 
is such that conduction occurs between points B-C and A-D. The signal 
f.sub.s flows from point C through diode D3, to diode D2 and finally to 
point B. The signals from terminal D flow through diode D4, D1 to terminal 
A. 
The local oscillator f.sub.c follows similar conduction paths. From point D 
to point B, it flows through diode D4 and D2. 
The relative phase relationship of the signal f.sub.s, the local oscillator 
f.sub.c, the image frequency f.sub.i, and the IF signal f.sub.IF is shown 
in the table of FIG. 3. The relative phases of f.sub.s and f.sub.c are 
obtained from the arrows shown in the equivalent circuit of FIG. 2. The 
arrows are drawn according to the winding orientation of the baluns 
indicated by the voltage polarity dots. The signal f.sub.s is illustrated 
as a solid arrow with the head pointing to the dot ends of the balun 
windings. The local oscillator signal f.sub.c uses a dash line arrow with 
the same orientation. Solid and dash line arrows are then drawn to the 
side of each diode in the same direction as the main arrows in the 
conduction path sequence previously described. To convert these arrows to 
a relative phase angle, the ground point at 70 MHz is defined as the 
terminals A, B, C and D. (These points are also ground at DC but are not 
ground at RF frequencies.) Since angles in this diagram will be either 
0.degree. or 180.degree., it has been assumed that if an arrow points to 
these IF ground points, the relative phase angles will be 0.degree.. If 
pointing away from these ground points, the phase angle will be 
180.degree.. As is known to those skilled in the art, the polarity 
connection of the diodes will affect the IF phase only, so it is assumed 
that a diode that points to the IF ground points A, B, C, or D will give a 
0.degree. f.sub.IF phase angle. However, the diodes pointing away from 
these points will add 180.degree. to the f.sub.IF phase. These phase 
corrections are shown as .DELTA..sub.IF in FIG. 3. The image frequency 
phase angle .theta..sub.I and the IF phase angle .theta..sub.IFS are 
calculated by the following formulas: 
__________________________________________________________________________ 
Equation Condition 
__________________________________________________________________________ 
(1) 
.theta..sub.I 
= .theta..sub.S - 2.theta. 
f.sub.s &gt; or &lt;f.sub.c 
Where 
.theta. 
= Phase of signal f.sub.s 
(2) 
.theta..sub.IFS 
= .theta..sub.S - .theta..sub.C 
f.sub.s &gt; f.sub.c 
.theta..sub.C 
= Phase of local 
oscillator f.sub.c 
(3) 
.theta..sub.IFS 
= -(.theta..sub.S - .theta..sub.C) 
f.sub.s &lt; f.sub.c 
.theta..sub.I 
= Phase of image f.sub.I 
.theta..sub.IFS 
= Phase of signal IFS 
__________________________________________________________________________ 
The examples in equations 1 through 3 assume the f.sub.s is not equal to 
f.sub.c. After the .theta..sub.IFS is calculated, the frequency final IF 
phase is obtained by adding .theta..sub.IF to .theta..sub.IFS. Note that 
the net result in phase of IF signals in the diodes is zero. The image 
frequency phase .theta..sub.I is the same as the f.sub.s phase which means 
that the image frequency generated by the diodes will be fed from the 
diodes out into the f.sub.s line. As will be realized, the image frequency 
is applicable only where the frequency translator is used as a 
downconverter. 
A very important part of a frequency translator is isolation. Isolation is 
obtained between f.sub.s and f.sub.c by reversing the dot connection of 
the balun line pair 7 and 8 when connected in parallel to pair 3 and 4. 
This causes the f.sub.c carrier to be 180.degree. out of phase in the 
f.sub.s line resulting in no f.sub.c voltage in the f.sub.s line. The 
cancellation of f.sub.s in the f.sub.c line occurs in the same manner. 
Intermediate frequency f.sub.IF isolation is obtained between f.sub.s and 
f.sub.c by the 180.degree. phase relationship between the f.sub.s and 
f.sub.c potentials at the IF terminals intermediate the respective diodes. 
As will be noted, the points A and B are at the same IF potential so this 
causes the f.sub.s and f.sub.c vectors in diodes D1 and D2 to be in 
parallel and since they point in opposite directions in these two diodes, 
there is no net voltage of f.sub.s or f.sub.c at the point intermediate 
these diodes where the IF signal is removed. 
Referring back to FIG. 1, a word of caution must be exercised about the 
connection of the diodes to the lines between the two baluns. It must be 
understood that locating the diode lead at different points along these 
balun lines will cause the relative phase of the signals on that line to 
change. It is, therefore, necessary that the diodes be connected at points 
of uniform phase between the four lines. This means that the diodes should 
be connected at the same vertical position assuming all line lengths are 
equal. Therefore, it is important not only that the diodes be located on 
these lines at the proper position, (relative phase locations), but also 
in the layout itself the line lengths must be made to maintain phase 
integrity between the two baluns. As an example, the voltage which appears 
between points 3-4 and 7-8 must be 180.degree. out of phase. Length of 
these lines should therefore be approximately equal. This 180.degree. 
phase relationship will provide cancellation therefore in each balun if 
the voltages of points 1-2 and 3-4 are 180.degree. out of phase with the 
voltage fed from points 5-6 and 7-8. Cancellation of the f.sub.s signal in 
the f.sub.c balun and vice versa depends therefore on the two voltages fed 
from one balun to the other maintaining an exact 180.degree. phase 
relationship. The diagram drawn in FIG. 1 is for convenience therefore and 
does not indicate the exact position of the diodes nor the exact length of 
lines. 
The double balanced frequency translator of FIG. 7 shows the same balun 
connection as FIG. 1 but with a different diode arrangement. This 
arrangement is full-wave whereas the arrangement of FIG. 1 is half-wave. 
By definition herein, the term full-wave is applied to translating 
apparatus wherein the diode paths between opposing terminal pairs allow 
conduction in both directions in signal translation operation. (Half-wave 
only allows one polarity of signal conduction.) While the output signals 
of FIG. 7 require less filtering, this embodiment does not have the 
simplicity of the fewer diodes of FIG. 1 or the lack of requirement for a 
balun as must be provided in FIG. 7. 
The reason that a balun is required in FIG. 7 is that the IF signal 
f.sub.IF is removed from point E-G and point F-H as a balanced signal is 
fed to a balun 170 (207) to be converted to an unbalanced output. This 
diode connection and the balun is shown in both FIGS. 7 and 8. Again, the 
same arrangement of arrows is utilized to explain the operation of the 
full-wave translator as used in connection with the half-wave translator. 
As will be obvious, a further advantage of the full-wave device of FIG. 7 
is that the power handling capability is increased since each individual 
diode dissipates less power. 
It is necessary in constructing the equivalent circuits to maintain the 
identity of each balun output, that is, terminals 1-2 and 3-4, etc., such 
that it is not possible to exchange these to obtain a more convenient 
layout. Thus, when laying out the equivalent circuit of any balun 
connection, it is necessary to maintain terminals 1 and 2 as a separate 
balun winding and, similarly, terminals 3 and 4 as another separate 
winding and so forth. However, great flexibility is obtained using the 
basic teaching as is illustrated by the alternate implementations of 
frequency converters shown in FIGS. 10, 12, and 13. Although the last 
three implementations are all illustrated in a half-wave form for 
simplicity of drawing, each of these implementations can easily be 
converted to the full-wave version similar to that shown in FIG. 7. 
In view of the equivalent circuits presented, it is believed that only a 
few comments are required for each of these modifications. As illustrated 
in FIG. 10, the carrier frequency signal is merely split with a power 
splitter and applied to the primary conductor of two separate baluns while 
the signal frequency is provided on a single signal conductor to be 
coupled to two sets of secondary paths. As shown in FIG. 12, the power 
splitter can either be on the same side as the unitary signal conductor or 
on the opposite side and the advantage of this approach is possible ease 
of implementation of connection of the various secondary paths as opposed 
to those illustrated in FIGS. 1 and 7. Also, the diodes are much easier to 
connect in FIG. 10. 
The same comments apply to FIG. 13 which uses a set of wires to maintain 
the appropriate relationship between the two sets of baluns and 
additionally provide electrical conductivity therebetween. While an RF 
absorbing material is illustrated between the microstrip circuit boards, 
this may not be necessary in some situations. The configuration of the 
enclosure is utilized to even more firmly maintain the structural 
positioning of the two sets of baluns and their attached diodes as well as 
the interconnection to the outside world. 
The equivalent circuits presented in FIGS. 4 and 5 provide a clearer 
presentation of the relative phases in hybrids using the present style 
baluns undisturbed by the presence of diodes. The relative phase of the 
baluns, as connected in FIGS. 4 and 5, are then presented in FIG. 6. Since 
the present invention is directed not only to frequency translators but 
also to hybrids generally, it was believed pertinent to illustrate the 
relative phases for this part of the inventive concept. 
As illustrated in my referenced application, the outside conductors of a 
coaxial cable can be split and connected to perform the cooperative signal 
coupling required to practice the present invention if so desired. 
In summary, the present invention comprises a hybrid formed by two dual 
balun pairs wherein the baluns are connected in parallel such that there 
is isolation between the two inputs. 
By adding diodes for the loads, the hybrid can be converted to a frequency 
translator for use as either an upconverter or downconverter which 
translator can be configured in any of many physical embodiments. 
Although I have illustrated various versions of the invention, I wish to be 
limited not by those embodiments shown but only by the scope of the 
appended claims wherein