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Publication numberUS3319194 A
Publication typeGrant
Publication dateMay 9, 1967
Filing dateOct 8, 1965
Priority dateOct 8, 1965
Publication numberUS 3319194 A, US 3319194A, US-A-3319194, US3319194 A, US3319194A
InventorsAdam Stephen F
Original AssigneeHewlett Packard Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Variable attenuator employing internal switching
US 3319194 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)


ATTORNEY United States Patent O Y 3,319,194 VARIABLE ATTENUATOR EMPLOYING INTERNAL SWITCHING Stephen F. Adam, Los Altos, Calif., assignor to Hewlett- Packard Company, Palo Alto, Calif., a corporation of California Filed Oct. 8, 1965, Ser. No. 493,985 3 Claims. (Cl. 333--S1) This invention relates to a high frequency signal attenuator which provides discrete steps of attenuation using separate attenuator elements which are all disposed in a transmission line configuration adjacent a common and continuous ground plane. An attenuator of this type obviates the need for complex mechanisms for switching both the signal and ground plane conductors of the transmission line structure and thus eliminates the introduction of unknown contact irnpedances in the ground plane conductor at the junctions of attenuator sections.

Accordingly, it is an object of the present invention to provide an improved step attenuator for high frequency signals.

In accordance with the illustrated embodiment of the present invention, a strip line structure is formed in a continuous ground plane conductor using a number of switchable sections, each including a resistive card attenuator and a straight-through conductor. Selection of either of the two signal paths is accomplished by defiecting the signal conductor from contact with one signal path to contact with the other signal path using magnetic or mechanical actuators. The effects of leakage paths `around the selected attenuating signal path may be overcome by establishing shorting paths simultaneously with the deflection of the signal conductor.

'I'hese and other objects of the present invention will be apparent from a reading of this specification and an inspection of the accompanying drawing in which:

FIGURE 1 is a front sectional view of the attenuator according to the present invention;

FIGURE 2 is an end sectional view of the attenuator of FIGURE 1; and

FIGURE 3 is a top sectional view of the attenuator of FIGURE 1.

In FIGURES 1, 2 and 3 of the drawing, there is shown a body 9 which forms the ground plane conductor of a strip line. Coaxial connectors 11, 13 at the ends of the body 9 each include a center .conductor 15 which is matched coupled to the strip line conductor 17 and an outer conductor 19 which is connected to the body 9. The strip line conductor 17 is supported on a dielectric slab 21 which is mounted in longitudinal grooves 23 in the side walls of the ground plane conductor or body 9.

At selected intervals along the length of the strip line conductor, a parallel pair of signal conductive elements 25 and 27 are disposed within the ground plane conductor 9 above and below the plane of the strip line conductor 17. The lower conductive element 25 forms a straight-through transmission path and includes a conductive strip line 29 supported by a dielectric slab 31 which is mounted in longitudinal slots 33. The width of the strip line 29 is decreased to maintain the characteristic impedance of the transmission line which is formed with closer spacing to the ground plane conductor 9. The upper conductive element forms an attenuating transmission path and includes a resistive film 35 which is disposed on a dielectric slab 37 mounted in longitudinal slots 39 and which is connected to the ground plane conductor 9 along its longitudinal edges 41. Contacts 43, 45 with the resistive film at restricted areas 3,3l9,l94 Patented May 9, 1967 ice at the ends of the slab 37 provide connection points for the signal transmission path. A resistive card attenuator of this type is described in connection with a coaxial transmission line in pending .U.S. patent application Ser. No. 393,127 tiled Aug. 31, 1964 by W. R. Hewlett and W. B. Wholey and issued on Jan. 4, 1966 as U.S. Patent 3,227,975. The strip line conductor 17 includes a iiexible portion 47 at each side of the parallel pair of signal transmission paths which serves as a switching element and which is tapered to maintainthe characteristic impedance of the transmission line. The switching element 47 is actuated either magnetically by suitable electromagnetics 49 and programming `power source 50 or mechanically by an actuator 51 and programming cam assembly 53. The actuator 51 may be any dielectric material which passes through an aperture in the ground plane conductor 9 that has dimensions which cause the aperture to operate as a waveguide beyond cutoi at the frequencies of signal applied to the attenuator so that signal leakage is negligible. A selected step of attenuation is provided by switching the strip line conductor 47 at both ends of the parallel pair of signal transmission paths to the resistive card path. When a plurality of such paths are provided, each with an attenuator card of selected value such as 5 db, 10 db, 20 db and 40 db, a number of attenuation steps in 5 db increments from 5 db to 75 db may be provided by selectively switching in either an attenuation transmission path or a straightthrough transmission path. This selection is provided in a conventional manner either by the programmed power source 50 (used with the magnetic actuators) or the cam assembly 53 (used with the mechanical actuator 51) in response to the position of the attenuation selector dial 55.

For higher attenuation sections, (e.g. 40 db or higher) spurious transmission paths around the attenuator card are formed along the closely-spaced straight-through transmission path of the parallel pair. This disturbs the attenuation vs. frequency response of the attenuator and may readily be suppressed by shorting slugs 57 which are brought into contact with the straight-through transmission path simultaneously with the magnetic or mechanical actuation of the switching elements of that attenuation section.

I claim:

1. Signal apparatus comprising:

a transmission line including a ground plane conductor;

a first signal transmission path of said transmission line within said ground plane conductor including a resistance layer on a dielectric;

means connecting the ground plane conductor and said resistive lm along the longitudinal edges thereof;

contacts at each end of said resistive film within a restricted area intermediate the longitudinal edges of the resistive film;

a second signal transmission path within the ground plane conductor in spaced plane-parallel relation to the resistance layer on a dielectric in the iirst signal transmission path;

another signal conductor at each end of the first and second signal transmission paths disposed intermediate the spacing thereof and within the ground plane conductor;

a switching element at each of the signal conductor adjacent the first and second signal transmission paths forming a portion of the length of said signal conductor; and

actuator means for simultaneously deecting said switching elements to the same one of said first and second signal transmission paths.

2. Signal apparatus comprising: 3. Signal apparatus as in claim 2 wherein:

a signal attenuating path and a signal conduction path each of said switching elements has a width which disposed in spaced relationship within a ground plane decreases with length from the signal conductor. conductor; t

a signal conductor at each end of the signal attenuat- 5 References Cited by the Examiner ing and signal conduction paths disposed inter- UNITED STATES PATENTS mediate the spacing thereof and within the ground 2 597 090 5/1952 Freeman 333 81 plane conductor;

a switching element attached at the end of each of the gnclelman signal conductors adjacent the signal attenuating and l0 3 087125 4/1963 shle 333:97

signal conduction paths forming a portion of the length of each of said signal conductors, each of ELI LIEBERMAN Primary Examiner the switching elements being capable of flexing over the length thereof; and HERMAN KARL SAALBACH, Examiner. actuator means for simultaneously deecting said 15 REHUNT, Assistant Examnen switching elements to the same one of said signal attenuating and vsignal conduction paths.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2597090 *May 19, 1949May 20, 1952Daven CompanyVariable attenuator
US2958054 *Nov 24, 1958Oct 25, 1960Amphenol Borg Electronics CorpImpedance terminated coaxial line switch apparatus
US2997669 *Feb 3, 1958Aug 22, 1961Thompson Ramo Wooldridge IncBroad band lobing switch
US3087125 *Jul 13, 1961Apr 23, 1963Gen ElectricCoaxial reed relay for interrupting the center conductor and simultaneously terminating its opened ends
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3753170 *Feb 10, 1971Aug 14, 1973Tektronix IncStep attenuator apparatus having attenuator stages selectively connected in cascade by cam actuated switches
US4695811 *Jul 28, 1986Sep 22, 1987Tektronix, Inc.High frequency coaxial switch
US4734661 *Dec 4, 1986Mar 29, 1988Tektronix, Inc.Coax to slab line connector and programmable attenuator using the same
US5039961 *Dec 21, 1989Aug 13, 1991Hewlett-Packard CompanyCoplanar attenuator element having tuning stubs
US5061909 *Apr 3, 1989Oct 29, 1991Marconi Instruments LimitedAttenuator switchably coupled to transmission path and means for switchably breaking the path
US5315273 *Oct 30, 1992May 24, 1994Teledyne Industries Inc.Attenuator relay
US6081125 *Dec 29, 1995Jun 27, 2000Rohde & Schwarz Gmbh & Co. KgNetwork analyzer
US6621391Apr 24, 2001Sep 16, 2003Agilent Technologies, Inc.Relay
US6707356Jun 18, 2003Mar 16, 2004Agilent Technologies, Inc.Method of constructing a relay
US6853273Dec 20, 2001Feb 8, 2005Agilent Technologies, Inc.Relay
US6933816Sep 14, 2004Aug 23, 2005Agilent Technologies, Inc.Relay
US7876185May 5, 2008Jan 25, 2011Teledyne Technologies IncorporatedElectromagnetic switch
US20020153980 *Dec 20, 2001Oct 24, 2002Freeman James A.Relay
US20050030135 *Sep 14, 2004Feb 10, 2005Freeman James A.Relay
US20050248425 *Jul 18, 2005Nov 10, 2005Freeman James ARelay
US20080283379 *May 18, 2007Nov 20, 2008Teledyne Technologies IncorporatedCoaxial switch with reduced tribo-electric charge accumulation
US20090273420 *May 5, 2008Nov 5, 2009Teledyne Technologies IncorporatedElectromagnetic switch
DE2265361B1 *Feb 10, 1972Sep 4, 1980Tektronix IncElektrische Schaltervorrichtung fuer Hochfrequenz mit einer Traegerplatte aus isolierendem Material und einem sich durch ein Loch der Traegerplatte erstreckenden Koppelelement
DE2265361C3 *Feb 10, 1972Sep 24, 1981Tektronix, Inc., 97005 Beaverton, Oreg., UsTitle not available
DE3417658A1 *May 12, 1984Apr 25, 1985Adret ElectroniqueEinfuegungsschalter fuer eine hoechstfrequenz-uebertragungsleitung
DE3724445A1 *Jul 23, 1987Feb 11, 1988Tektronix IncHochfrequenz-coaxialschalter
DE4226106C1 *Aug 7, 1992Sep 16, 1993Rohde & Schwarz Gmbh & Co Kg, 81671 Muenchen, DeProgrammable calibration line between 2 conductor planes - has gap in inner conductor bridged by 2 alternate 4-pole networks by deflection of free inner conductor ends
DE4401068A1 *Jan 15, 1994Mar 2, 1995Rohde & SchwarzNetwork analyser
U.S. Classification333/81.00R, 333/260, 333/81.00A, 333/262
International ClassificationH01P1/22
Cooperative ClassificationH01P1/225
European ClassificationH01P1/22C