US3659227A - Switch-controlled directional coupler - Google Patents
Switch-controlled directional coupler Download PDFInfo
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- US3659227A US3659227A US70024A US3659227DA US3659227A US 3659227 A US3659227 A US 3659227A US 70024 A US70024 A US 70024A US 3659227D A US3659227D A US 3659227DA US 3659227 A US3659227 A US 3659227A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/10—Auxiliary devices for switching or interrupting
Definitions
- the invention relates to a branch waveguide coupler net work including switches for varying the coupling.
- branch waveguide coupler circuit composed of a main waveguide (i.e., first transmission path) and an auxiliary waveguide (second transmission path) connected together by branch waveguides (branch transmission paths) as a directional coupler for microwaves.
- Each branch is effectively a quarter wavelength long an is spaced effectively a quarter wavelength from adjacent branches.
- the method for determining the small difference between the actual and the effective lengths of the waveguide elements is discussed in Branch Waveguide Coupler Design Charts," pages l03-l06, The Microwave Journal. January 1963.
- microwave energy is coupled from one (input) end of the main waveguide to the other (output) end of the auxiliary waveguide.
- each branch By placing a shorting switch in the center of each branch, using at least three branches, it becomes possible to cause the input wave in the main waveguide to leave by an output port which is also in the main waveguide.
- the shorting switches when operated, make each branch appear as a shorted oneeighth wavelength line, thereby causing the auxiliary line to be more or less isolated from the main line input.
- a two-branch coupler in the form of a 90 3 dB hybrid is used with series or shorting switches in the center of each branch, a 50 percent directional coupler can be switched as was the previously described 100 percent coupler.
- FIG. 1 is a schematic representation of a four-branch 100 percent directional coupler with switches at the midpoint of each branch.
- FIG. 2 is'a schematic representation of a two-branch 50 percent directional coupler with switches at the midpoint of each branch.
- FIG. 3 is a schematic representation of an alternative embodiment of the invention using series mounted diodes in the coupler branch arms.
- FIG. 1 is a schematic representation of a branch coupler circuit having each of its four branches supplied at its center with a shorting switch. This is a 100 percent coupler and could have as few as three branches or many more than four branches.
- a main waveguide l and an auxiliary waveguide 2 are connected by four branch waveguides 3, 4, 5, and 6.
- Each of the branch waveguides is effectively one-quarter wavelength long, and the branch waveguides are spaced apart by an effective distance of onequarter wavelength. 7
- a shorting switch is connected at the center of each branch.
- Switches 7, 8, 9, and 10 are thus respectively connected at the centers of lines 3, 4, 5, and 6. Therefore each switch is effectively one-eighth wavelength distant from the end of the branch, causing the branch, when shorted by the switch, to appear as a shorted one-eighth wavelength line.
- the switches are preferably d.c. biased PIN diodes placed in the symmetry plane of the branches and provided with a variable bias to selectively cause the diode switch to appear as an open circuit or as a short circuit to microwave energy.
- Other semiconductor diodes, and other types of switches such as power-level-sensitive gas tubes, or for lower response speeds, mechanical shutters and the like, could be used.
- This switch has broader bandwidth than the more common shorted quarter-wavelength switch, has higher power than the same switch in the 100 percent coupler condition since the diodes split the power, and can be'more conveniently constructed as a microwave integrated circuit. Power handling and bandwidth are improved by the addition of more branches to the coupler.
- FIG. 2 is a schematic representation of a branch-type hybrid circuit with switches, 15 and 16, preferably PIN diodes, mounted at the midpoints of the two branches l7 and 18 connecting the two main transmission lines 19 and 20.
- the hybrid circuit is a 3 dB hybrid.
- This coupler is a 50 percent coupler, while the coupler of FIG. 1 is a percent coupler.
- This coupler is particularly adapted for use with antenna systems, where one output port is connected to a horizontally polarized antenna and the other output port is connected to a vertically polarized antenna.
- With the switch diodes forward biased there is no connection between arms 19 and 20, the input signal is applied to only one output port and thus to only one antenna, and the antenna system produces a linearly polarized signal.
- the switch diodes are reverse biased, 50 percent of the signal goes to each output port and from there to each antenna, resulting in a circularly polarized signal from the antenna system.
- the main lines 19 and2 0 are connected'when the diodes are reverse biased. This causes half power to couple from the first side tothe secondoutput port with a 90 shift in the radiofrequency energy.
- the 90 shift is inherent in the 90 hybrid used. Reversing the diode switch bias thus causes the radiation from the antenna to be preset either. to linear or circular polarization.
- the coupler shown in FIG. 3 is a 50 percent coupler and, like that of FIG. 2, comprises two main transmission lines 22 and 23 connected by branch lines 24 and 25 each broken by a gap at its midpoint. Across each gap there is connected switch means 26 which preferably is a PIN diode, and which when operated as by forward biasing the diode establishes coupling between the lines 22 and 23. When the diodes 26 are reverse biased the branch line gaps are not closed thereby, and the branch lines then function effectively as eighth-wavelength open end stubs.
- the diodes may be selectively operated to introduce short circuits into the branch lines at their midpoints to block coupling of wave energy through the branch lines, or to remove these short circuits and enable such coupling.
- the diodes may be selectively operated to provide continuity through the branch lines to enable coupling therethrough, or to open circuit the branch lines at their midpoint gaps so as to block such coupling.
- a directional coupler for transmitting waves of a given wavelength comprising:
- first wave transmission path means having an input port and an output port spaced to provide a transmission path therebetween of effective lengthgreater than one-fourth of said wavelength
- second-wave transmission path means having an input port and an output port spaced to provide a transmission path therebetween of effective length greater than onefourth of said wavelength
- each said switch means comprises a diode adapted to be forward biased and reverse biased selectively, whereby the diode enables coupling of microwave energy through its associated branch path transmission means in one bias condition and blocksthe coupling of microwave energy through said branch path transmission means in the other bias condition.
- a circuit according to claim 2 wherein said diode is connected into said branch transmission path means so as to short circuit and thus block coupling through said branch transmission path means when forward biased and to remove such short and permit coupling through said branch transmission path means when reverse biased.
- branch transmission path means include midpoint gaps across which are connected said diodes, whereby the diodes when forward biased providev continuity through said branch transmission path means and vwhen reverse biased break such continuity and block the coupling of microwave energy through said branch transmission path means.
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- Waveguide Switches, Polarizers, And Phase Shifters (AREA)
Abstract
A branch waveguide coupler network using diode or other switches at the midpoint of each branch to control the coupling of the input signal to one of two output ports. Both 50 percent and 100 percent coupling systems are disclosed.
Description
United States Patent Whistler 1451 Apr. 25, 1972 [s41 SWITCH-CONTROLLED DIRECTIONAL [56] References Cited PLE COU R T m I S N Y UNITED STATES PATENTS W [721 yracuse 2,975,381 3/1961 Reed et al .333/10 [73] Assignee: General Electric Company v 'Primary Examiner-Paul LQGensler [22] Fned' sept' Attorney-Carl W. Baker, Richard V. Lang, Frank L. Neu- [21] App]. No.: 70,024 hauser, Oscar B. Waddell and Joseph B. Forman 52 us. c1. ..a33/7,333/10 [57] ABSTRACT [51] int. Ci. "B l A branch waveguide coupler network using diode or other [58] Fi ld ofs switches at the midpoint of each branch to control the coupling of the input signal to one of two output ports. Both 50 percent and 100 percent coupling systems are disclosed.
4 Claims, 3 Drawing Figures 903d8 I? 'HYBRiD SWITCH SWITCH I6 1511 .8- e
1 SWITCH-CONTROLLED DIRECTIONAL COUPLER BACKGROUND OF THE INVENTION .The invention herein described was made in the course of or under a contract or subcontract thereunder, with the United States Air Force.
The invention relates to a branch waveguide coupler net work including switches for varying the coupling.
It is known to use a branch waveguide coupler circuit composed of a main waveguide (i.e., first transmission path) and an auxiliary waveguide (second transmission path) connected together by branch waveguides (branch transmission paths) as a directional coupler for microwaves. Each branch is effectively a quarter wavelength long an is spaced effectively a quarter wavelength from adjacent branches. The method for determining the small difference between the actual and the effective lengths of the waveguide elements is discussed in Branch Waveguide Coupler Design Charts," pages l03-l06, The Microwave Journal. January 1963. In a normally constructed coupler of this sort, microwave energy is coupled from one (input) end of the main waveguide to the other (output) end of the auxiliary waveguide.
SUMMARY OF THE INVENTION I By placing a shorting switch in the center of each branch, using at least three branches, it becomes possible to cause the input wave in the main waveguide to leave by an output port which is also in the main waveguide. The shorting switches, when operated, make each branch appear as a shorted oneeighth wavelength line, thereby causing the auxiliary line to be more or less isolated from the main line input.
As an alternative to the shorting switches just described, it also is possible to control coupling by use of series switches each connected across a midpoint gap in one of the coupler branch lines. These series switches, when operated, close the gaps in the branch lines and thus enable coupling through them; when the switches are not operated the branch lines appear as open end one-eighth wavelength stubs, thereby isolating the main and auxiliary lines. v v
If, instead of using three branches, a two-branch coupler in the form of a 90 3 dB hybrid is used with series or shorting switches in the center of each branch, a 50 percent directional coupler can be switched as was the previously described 100 percent coupler. I
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a four-branch 100 percent directional coupler with switches at the midpoint of each branch.
FIG. 2 is'a schematic representation of a two-branch 50 percent directional coupler with switches at the midpoint of each branch.
FIG. 3 is a schematic representation of an alternative embodiment of the invention using series mounted diodes in the coupler branch arms.
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic representation of a branch coupler circuit having each of its four branches supplied at its center with a shorting switch. This is a 100 percent coupler and could have as few as three branches or many more than four branches. In the circuit shown, a main waveguide l and an auxiliary waveguide 2 are connected by four branch waveguides 3, 4, 5, and 6. Each of the branch waveguides is effectively one-quarter wavelength long, and the branch waveguides are spaced apart by an effective distance of onequarter wavelength. 7
A shorting switch is connected at the center of each branch. Switches 7, 8, 9, and 10 are thus respectively connected at the centers of lines 3, 4, 5, and 6. Therefore each switch is effectively one-eighth wavelength distant from the end of the branch, causing the branch, when shorted by the switch, to appear as a shorted one-eighth wavelength line.
The switches are preferably d.c. biased PIN diodes placed in the symmetry plane of the branches and provided with a variable bias to selectively cause the diode switch to appear as an open circuit or as a short circuit to microwave energy. Other semiconductor diodes, and other types of switches such as power-level-sensitive gas tubes, or for lower response speeds, mechanical shutters and the like, could be used.
When the switches are open, an input signal applied to input port A in main waveguide 1 would be coupled to output port B in auxiliary waveguide 2. Similarly, signals from input port B are applied to output port A. However, when the switches are shorted, signals from input port A are coupled to output port A and signals from input port B are coupled to output port B. The degree of isolation depends on hybrid design and diode mismatch for one switch position and diode leakage in the other position.
This switch has broader bandwidth than the more common shorted quarter-wavelength switch, has higher power than the same switch in the 100 percent coupler condition since the diodes split the power, and can be'more conveniently constructed as a microwave integrated circuit. Power handling and bandwidth are improved by the addition of more branches to the coupler.
FIG. 2 is a schematic representation of a branch-type hybrid circuit with switches, 15 and 16, preferably PIN diodes, mounted at the midpoints of the two branches l7 and 18 connecting the two main transmission lines 19 and 20. The hybrid circuit is a 3 dB hybrid. This coupler is a 50 percent coupler, while the coupler of FIG. 1 is a percent coupler. This coupler is particularly adapted for use with antenna systems, where one output port is connected to a horizontally polarized antenna and the other output port is connected to a vertically polarized antenna. With the switch diodes forward biased, there is no connection between arms 19 and 20, the input signal is applied to only one output port and thus to only one antenna, and the antenna system produces a linearly polarized signal. When the switch diodesare reverse biased, 50 percent of the signal goes to each output port and from there to each antenna, resulting in a circularly polarized signal from the antenna system.
The main lines 19 and2 0 are connected'when the diodes are reverse biased. This causes half power to couple from the first side tothe secondoutput port with a 90 shift in the radiofrequency energy. The 90 shift is inherent in the 90 hybrid used. Reversing the diode switch bias thus causes the radiation from the antenna to be preset either. to linear or circular polarization.
With reference now to FIG. 3, the coupler illustrated'differs from those previously described in utilizing series mounted diodes in lieu of shorting switches as in the embodiments of FIGS. 1 and 2. The coupler shown in FIG. 3 is a 50 percent coupler and, like that of FIG. 2, comprises two main transmission lines 22 and 23 connected by branch lines 24 and 25 each broken by a gap at its midpoint. Across each gap there is connected switch means 26 which preferably is a PIN diode, and which when operated as by forward biasing the diode establishes coupling between the lines 22 and 23. When the diodes 26 are reverse biased the branch line gaps are not closed thereby, and the branch lines then function effectively as eighth-wavelength open end stubs.
Thus in the couplers of FIGS. 1 and 2 the diodes may be selectively operated to introduce short circuits into the branch lines at their midpoints to block coupling of wave energy through the branch lines, or to remove these short circuits and enable such coupling. In the coupler of FIG. 3 the diodes may be selectively operated to provide continuity through the branch lines to enable coupling therethrough, or to open circuit the branch lines at their midpoint gaps so as to block such coupling.
What is claimed as new and desired to be secured by Letters Patent of the United States is:'
1. In a directional coupler for transmitting waves of a given wavelength comprising:
a. first wave transmission path means having an input port and an output port spaced to provide a transmission path therebetween of effective lengthgreater than one-fourth of said wavelength,
b. second-wave transmission path means having an input port and an output port spaced to provide a transmission path therebetween of effective length greater than onefourth of said wavelength,
c. a pair of branch transmission path means connected between the first path means and the second path means between their respective input and output ports, each of "therethrough between the first and the second path means.
2. A circuit according to claim 1 wherein each said switch meanscomprises a diode adapted to be forward biased and reverse biased selectively, whereby the diode enables coupling of microwave energy through its associated branch path transmission means in one bias condition and blocksthe coupling of microwave energy through said branch path transmission means in the other bias condition.
3. A circuit according to claim 2 wherein said diode is connected into said branch transmission path means so as to short circuit and thus block coupling through said branch transmission path means when forward biased and to remove such short and permit coupling through said branch transmission path means when reverse biased.
4. A circuit according to claim 2 wherein said branch transmission path means include midpoint gaps across which are connected said diodes, whereby the diodes when forward biased providev continuity through said branch transmission path means and vwhen reverse biased break such continuity and block the coupling of microwave energy through said branch transmission path means.
Claims (4)
1. In a directional coupler for transmitting waves of a given wavelength comprising: a. first wave transmission path means having an input port and an output port spaced to provide a transmission path therebetween of effective length greater than one-fourth of said wavelength, b. second wave transmission path means having an input port and an output port spaced to provide a transmission path therebetween of effective length greater than one-fourth of said wavelength, c. a pair of branch transmission path means connected between the first path means and the second path means between their respective input and output ports, each of the branch path means being effectively one-fourth as long as said wavelength and being spaced from the other branch transmission path means by an effective distance one-fourth as long as said wavelength so as to form with said first and second wave transmission path means a 90* - 3 dB hybrid coupler, the improvement for selectively controlling operation of the coupler comprising: d. switch means connected at the midpoint of each branch path transmission means and selectively operable to block coupling through each branch path transmission means at its midpoint or to enable 50 percent coupling therethrough between the first and the second path means.
2. A circuit according to claim 1 wherein each said switch means comprises a diode adapted to be forward biased and reverse biased selectively, whereby the diode enables coupling of microwave energy through its associated branch path transmission means in one bias condition and blocks the coupling of microwave energy through said branch path transmission means in the other bias condition.
3. A circuit according to claim 2 wherein said diode is connected into said branch transmission path means so as to short circuit and thus block coupling through said branch transmission path means when forward biased and to remove such short and permit coupling through said branch transmission path means when reverse biased.
4. A circuit according to claim 2 wherein said branch transmission path means include midpoint gaps across which are connected said diodes, whereby the diodes when forward biased provide continuity through said branch transmission path means and when reverse biased break such continuity and block the coupling of microwave energy through said branch transmission path means.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US7002470A | 1970-09-08 | 1970-09-08 |
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| US3659227A true US3659227A (en) | 1972-04-25 |
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| US70024A Expired - Lifetime US3659227A (en) | 1970-09-08 | 1970-09-08 | Switch-controlled directional coupler |
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Cited By (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4165497A (en) * | 1977-11-11 | 1979-08-21 | Aiken Industries Inc. | Wideband RF switching matrix |
| US4190815A (en) * | 1978-03-09 | 1980-02-26 | The United States Of America As Represented By The Secretary Of The Air Force | High power hybrid switch |
| FR2556507A1 (en) * | 1983-12-09 | 1985-06-14 | Europ Agence Spatiale | Waveguide structure for switching electromagnetic waves between several gateways |
| WO1987004012A1 (en) * | 1985-12-19 | 1987-07-02 | Hughes Aircraft Company | Hybrid power combiner and amplitude controller |
| US4814780A (en) * | 1988-03-11 | 1989-03-21 | Itt Gilfillan, A Division Of Itt Corporation | Variable directional coupler |
| USH880H (en) * | 1987-08-10 | 1991-01-01 | The United States Of America As Represented By The Secretary Of The Air Force | In-plane transmission line crossover |
| DE3940252A1 (en) * | 1989-12-06 | 1991-06-13 | Philips Patentverwaltung | Nuclear resonance device - uses 2 cascaded directional couplers for transmitter-receiver decoupling, full transmission power and undamped received signal transfer |
| US6225874B1 (en) * | 1998-05-29 | 2001-05-01 | Agilent Technologies Inc. | Coupling structure as a signal switch |
| US6359530B1 (en) | 2000-03-24 | 2002-03-19 | General Signal Corporation | Switching waveguide directional coupler and method |
| US6667670B2 (en) * | 2000-07-25 | 2003-12-23 | Korea Institute Of Science And Technology | Microwave double-pole double-throw switch and microwave divide/through switch and power amplifier using thereof |
| US20050052259A1 (en) * | 2003-09-09 | 2005-03-10 | Ntt Docomo, Inc | Quadrature hybrid circuit |
| US20050093640A1 (en) * | 1998-07-31 | 2005-05-05 | James Brady | Apparatus and method for reducing propagation delay in a conductor |
| US20050143026A1 (en) * | 2003-12-31 | 2005-06-30 | Wj Communications, Inc. | Integrated switching device for routing radio frequency signals |
| WO2005065423A2 (en) * | 2003-12-31 | 2005-07-21 | Wj Communications, Inc. | Multiprotocol rfid reader |
| JP2005253059A (en) * | 2004-02-03 | 2005-09-15 | Ntt Docomo Inc | Variable resonator and variable phase shifter |
| US20050231367A1 (en) * | 2003-12-31 | 2005-10-20 | Wj Communications, Inc. | Multiprotocol RFID reader |
| US20070008132A1 (en) * | 2004-12-23 | 2007-01-11 | Bellantoni John V | Switchable directional coupler for use with RF devices |
| US20080278385A1 (en) * | 2007-05-07 | 2008-11-13 | Tera-X, Llc | Broadband antennas and related systems, devices, and methods |
| US7768458B2 (en) * | 2007-05-07 | 2010-08-03 | Tera-X, Llc | Systems, methods and devices for improved imaging |
| US7804455B2 (en) * | 2006-12-05 | 2010-09-28 | Electronics And Telecommunications Reseach Institute | Antenna apparatus for linearly polarized diversity antenna in RFID reader and method of controlling the antenna apparatus |
| US20110168891A1 (en) * | 2007-05-07 | 2011-07-14 | Tera-X, Llc | Systems, methods and devices for improved imaging and sensation of objects |
| US20130207741A1 (en) * | 2012-02-13 | 2013-08-15 | Qualcomm Incorporated | Programmable directional coupler |
| US20140062613A1 (en) * | 2011-10-31 | 2014-03-06 | Technology Service Corporation | Systems and methods for high power rf channel selection |
| DE102013214818A1 (en) * | 2013-04-29 | 2014-10-30 | Rohde & Schwarz Gmbh & Co. Kg | Coupled line system with controllable transmission behavior |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2975381A (en) * | 1957-02-21 | 1961-03-14 | Raytheon Co | Duplexers |
-
1970
- 1970-09-08 US US70024A patent/US3659227A/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2975381A (en) * | 1957-02-21 | 1961-03-14 | Raytheon Co | Duplexers |
Cited By (40)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4165497A (en) * | 1977-11-11 | 1979-08-21 | Aiken Industries Inc. | Wideband RF switching matrix |
| US4190815A (en) * | 1978-03-09 | 1980-02-26 | The United States Of America As Represented By The Secretary Of The Air Force | High power hybrid switch |
| FR2556507A1 (en) * | 1983-12-09 | 1985-06-14 | Europ Agence Spatiale | Waveguide structure for switching electromagnetic waves between several gateways |
| WO1987004012A1 (en) * | 1985-12-19 | 1987-07-02 | Hughes Aircraft Company | Hybrid power combiner and amplitude controller |
| US4697160A (en) * | 1985-12-19 | 1987-09-29 | Hughes Aircraft Company | Hybrid power combiner and amplitude controller |
| USH880H (en) * | 1987-08-10 | 1991-01-01 | The United States Of America As Represented By The Secretary Of The Air Force | In-plane transmission line crossover |
| US4814780A (en) * | 1988-03-11 | 1989-03-21 | Itt Gilfillan, A Division Of Itt Corporation | Variable directional coupler |
| DE3940252A1 (en) * | 1989-12-06 | 1991-06-13 | Philips Patentverwaltung | Nuclear resonance device - uses 2 cascaded directional couplers for transmitter-receiver decoupling, full transmission power and undamped received signal transfer |
| US6225874B1 (en) * | 1998-05-29 | 2001-05-01 | Agilent Technologies Inc. | Coupling structure as a signal switch |
| US20050093640A1 (en) * | 1998-07-31 | 2005-05-05 | James Brady | Apparatus and method for reducing propagation delay in a conductor |
| US20090206946A1 (en) * | 1998-07-31 | 2009-08-20 | James Brady | Apparatus and method for reducing propagation delay in a conductor |
| US7495526B2 (en) * | 1998-07-31 | 2009-02-24 | Stmicroelectronics, Inc. | Apparatus and method for reducing propagation delay in a conductor system selectable to carry a single signal or independent signals |
| US6359530B1 (en) | 2000-03-24 | 2002-03-19 | General Signal Corporation | Switching waveguide directional coupler and method |
| US6667670B2 (en) * | 2000-07-25 | 2003-12-23 | Korea Institute Of Science And Technology | Microwave double-pole double-throw switch and microwave divide/through switch and power amplifier using thereof |
| US20050052259A1 (en) * | 2003-09-09 | 2005-03-10 | Ntt Docomo, Inc | Quadrature hybrid circuit |
| EP1515390A1 (en) * | 2003-09-09 | 2005-03-16 | NTT DoCoMo, Inc. | Quadrature hybrid circuit |
| JP2005086533A (en) * | 2003-09-09 | 2005-03-31 | Ntt Docomo Inc | 90 degrees hybrid circuit |
| CN100359752C (en) * | 2003-09-09 | 2008-01-02 | 株式会社Ntt都科摩 | 90 degrees hybrid circuit |
| US7084717B2 (en) | 2003-09-09 | 2006-08-01 | Ntt Docomo, Inc. | Quadrature hybrid circuit |
| WO2005065423A3 (en) * | 2003-12-31 | 2006-09-28 | Wj Communications Inc | Multiprotocol rfid reader |
| US7197279B2 (en) | 2003-12-31 | 2007-03-27 | Wj Communications, Inc. | Multiprotocol RFID reader |
| US7239858B2 (en) | 2003-12-31 | 2007-07-03 | Wj Communications, Inc. | Integrated switching device for routing radio frequency signals |
| US20050231367A1 (en) * | 2003-12-31 | 2005-10-20 | Wj Communications, Inc. | Multiprotocol RFID reader |
| WO2005065423A2 (en) * | 2003-12-31 | 2005-07-21 | Wj Communications, Inc. | Multiprotocol rfid reader |
| US20050143026A1 (en) * | 2003-12-31 | 2005-06-30 | Wj Communications, Inc. | Integrated switching device for routing radio frequency signals |
| JP2005253059A (en) * | 2004-02-03 | 2005-09-15 | Ntt Docomo Inc | Variable resonator and variable phase shifter |
| US20070008132A1 (en) * | 2004-12-23 | 2007-01-11 | Bellantoni John V | Switchable directional coupler for use with RF devices |
| US7804455B2 (en) * | 2006-12-05 | 2010-09-28 | Electronics And Telecommunications Reseach Institute | Antenna apparatus for linearly polarized diversity antenna in RFID reader and method of controlling the antenna apparatus |
| US20100315314A1 (en) * | 2007-05-07 | 2010-12-16 | Tera-X, Llc | Systems, methods and devices for improved imaging |
| US7768458B2 (en) * | 2007-05-07 | 2010-08-03 | Tera-X, Llc | Systems, methods and devices for improved imaging |
| US20080278385A1 (en) * | 2007-05-07 | 2008-11-13 | Tera-X, Llc | Broadband antennas and related systems, devices, and methods |
| US20110168891A1 (en) * | 2007-05-07 | 2011-07-14 | Tera-X, Llc | Systems, methods and devices for improved imaging and sensation of objects |
| US8059037B2 (en) | 2007-05-07 | 2011-11-15 | Tera-X, Llc | Broadband antennas and related systems, devices, and methods |
| US8098209B2 (en) | 2007-05-07 | 2012-01-17 | Tera-X, Llc | Systems, methods and devices for improved imaging |
| US20140062613A1 (en) * | 2011-10-31 | 2014-03-06 | Technology Service Corporation | Systems and methods for high power rf channel selection |
| US9941561B2 (en) | 2011-10-31 | 2018-04-10 | Technology Service Corporation | Systems and methods for high power RF channel selection |
| US20130207741A1 (en) * | 2012-02-13 | 2013-08-15 | Qualcomm Incorporated | Programmable directional coupler |
| DE102013214818A1 (en) * | 2013-04-29 | 2014-10-30 | Rohde & Schwarz Gmbh & Co. Kg | Coupled line system with controllable transmission behavior |
| US9484611B2 (en) | 2013-04-29 | 2016-11-01 | Rohde & Schwarz Gmbh & Co. Kg | Coupled line system with controllable transmission behaviour |
| DE102013214818B4 (en) | 2013-04-29 | 2024-12-05 | Rohde & Schwarz GmbH & Co. Kommanditgesellschaft | Coupled line system with controllable transmission behavior |
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