IEEE International Conference on Plasma Science, 2000
Summary form only given. We report on the status of a very compact, high efficiency harmonic ampl... more Summary form only given. We report on the status of a very compact, high efficiency harmonic amplifier (HARA) prototype experiment. In this experiment, a 6 kV 200 mA pencil electron beam undergoes circular scanning-modulation inside a short microwave resonator operating in circular polarization at 5.85 GHz. A 35 GHz output cavity operating at the 6th harmonic of the drive frequency
Terahertz for Military and Security Applications II, 2004
Microwave Technologies is developing a revolutionary miniature terahertz traveling-wave microtube... more Microwave Technologies is developing a revolutionary miniature terahertz traveling-wave microtube (TTM) that will provide sub-millimeter wave radiation for many civilian and military applications. This new concept uses a dielectric microtube in conjunction with a microscopic electron beam. The electron beam is produced by a single micron-sized emitter, which lies underneath the microtube to produce high-power terahertz electromagnetic radiation. The TTM should be easily fabricated using state-of-the-art solid-state technology, and will be a pioneering step towards combining vacuum tube technology with solid-state microfabrication technology. Some of the applications for these exciting new devices include terahertz high-resolution radar, THz chemical and biological sensing, commercial THz line-of-sight networking and ultrahigh-speed computers. A key application of the device under development will be as a miniature terahertz source for biological and chemical spectroscopy. We present detailed numerical and computational analysis of this concept. We also present initial experimental testing of a dielectric microtube designed to operate at 0.1 THz. Once successfully developed, TTMs will be the basis for a new generation of high power terahertz sources capable of producing ultrahigh frequency radiation with high efficiency in an amazingly compact and lightweight package.
We are developing a compact high-frequency electron buncher for applications in accelerator and m... more We are developing a compact high-frequency electron buncher for applications in accelerator and microwave tubes. This electron buncher uses a conventional Pierce-type electron gun with a gated field-emitter-array cathode for the production of short, 10kV, 100mA electron bunches. The width of the electron bunches can be adjusted to be a small part (10parameters. We have tested these cold cathodes in
The 33rd IEEE International Conference on Plasma Science, 2006. ICOPS 2006. IEEE Conference Record - Abstracts., 2006
Summary form only given. We are carrying out the development of a compact W-band dielectric trave... more Summary form only given. We are carrying out the development of a compact W-band dielectric traveling-wave tube (DTWT) amplifier. The DTWT amplifier is based on the interaction between a magnetized electron beam and the fields of a traveling wave inside a very compact dielectric waveguide. A high permittivity dielectric waveguide is used to slow down the wave and replaces the less efficient helix structures used in conventional traveling-wave tubes. A novel approach in this development is the use of micromachining techniques for the fabrication of the various components of this amplifier. We will present experimental results of RF and beam transport experiments along the DTWT circuit. The DTWT should be capable of producing millimeter-wave radiation for future military battlespace applications
IEEE Conference Record - Abstracts. 2005 IEEE International Conference on Plasma Science, 2005
Summary form only given. We have begun the development of a compact W-band dielectric traveling-w... more Summary form only given. We have begun the development of a compact W-band dielectric traveling-wave tube (DTWT) prototype. The DTWT amplifier is based on the interaction between a well-collimated electron beam and the electromagnetic fields of a traveling wave inside a very compact dielectric waveguide. The dielectric waveguide is used to slow down the wave and replaces the less efficient helix structures used in conventional traveling-wave tubes. A novel approach in this development is the use of micromachining techniques for the fabrication of the various components of this amplifier. We will present design considerations for a 94 GHz, 10-watt amplifier. The DTWT should be capable of replacing conventional traveling-wave tubes in telecommunication systems for future space applications by offering substantial improvements in size, weight, and especially efficiency over its counterparts
Creation of a rotating wave field in a high-Q resonator usually requires the resonator to be tune... more Creation of a rotating wave field in a high-Q resonator usually requires the resonator to be tuned to compensate for manufacturing errors. The tuning of a rotating wave resonator is more complicated than that of a common resonator. A theory of tuning rotating wave resonators and a procedure for efficiently carrying out this tuning is presented in this paper, along with the authors’ experience in tuning a rotating TM110 mode in a 1.28 GHz microwave resonator.
2007 IEEE International Vacuum Electronics Conference, 2007
Summary form only given.This paper presents that the microwave technologies is developing a compa... more Summary form only given.This paper presents that the microwave technologies is developing a compact two-cavity amplifier that uses a rugged carbon-nanotube cold-cathode to produce microwave radiation with very high efficiency. The entire RF circuit and electron gun have already been built and are currently under testing. We will present experimental results of electron beam generation and transport along the C-band RF circuit. Initial microwave amplification results will be also reported. This new amplifier should be capable of replacing conventional traveling- wave tubes in future radar and communication systems by offering substantial improvements in size, weight, and especially efficiency over its counterparts. This work is supported by the missile defense agency under the small business innovation research program.
In this paper, we describe a miniature power-combiner for monolithic millimeter-wave integrated c... more In this paper, we describe a miniature power-combiner for monolithic millimeter-wave integrated circuit (MMIC) chips using spatial power-combining with cavity modes. We have designed GaN MMIC power amplifier chips for 94 GHz, and illustrate the concept of the W-Band Spatial Power Combining Amplifier (WSPCA). Using 1 Watt, 94 GHz MMIC chips in a two-way cavity mode combiner, we were able to achieve 2 Watts of output power with 9 dB gain and 15 % PAE. This technique could be extended to high power MMICs and larger numbers of chips to achieve higher output power in a compact size. Current applications include earth science radar, and may be extended to other applications requiring wider bandwidth.
The Deployable Optical Receive Aperture (DORA), a new technology being developed jointly between ... more The Deployable Optical Receive Aperture (DORA), a new technology being developed jointly between Jet Propulsion Laboratory (JPL) and Arizona State University (ASU), is based on deploying arrays of fast optical detectors to create large receive apertures and seeks to achieve gigabit connectivity at distances of thousands of kilometers. Small spacecraft forming the LunaNet communications network and equipped with optical communications systems, such as the proposed DORA aperture, should be able to communicate at Gigabit per second rates over long distances. This data rate enhancement can allow gigabit per second connectivity between lunar assets (astronauts, rovers, instruments) and the lunar gateway. Under sponsorship of NASA's Small Spacecraft Technology Program (SSTP), JPL is deploying the DORA payload and ASU is developing a 3U CubeSat for a follow on LEO mission to demonstrate DORA's capabilities. The basic DORA payload consists of 5 detector panels, a transmitting telescope and processing units. Each detector panel contains dozens of power-combined detectors to mimic a large optical receive aperture. The total receive aperture of DORA is provided by sum of the effective detecting area of the 5 panels. The transmit telescope includes a 200mW, 850nm laser and a voice-coil fast steering mirror (FSM). The resulting DORA terminal should be able to provide duplex connectivity at rates up to 1 gigabit per second at the distances of interest. We have designed the entire DORA payload and plan to present the test results of our DORA engineering model. These results include angle-of-arrival, data rate and bit error rate measurements.
We have implemented a single wideband receiver package that could cover the 8 to 48 GHz frequency... more We have implemented a single wideband receiver package that could cover the 8 to 48 GHz frequency range of the ngVLA. The current JVLA covers this frequency range employing five distinct receiver packages. We estimate that reducing the number of receiving systems required to cover the full frequency range should reduce operating costs. The receiver package we developed consists of a quad-ridge feed horn, low-noise amplifiers (LNA), and a down-converter to analog intermediate frequencies. Both the feedhorn and the LNA are cryogenically cooled. On the LNA front we pursued two 8-48 GHz MMIC designs, the first using 70-nm gallium arsenide, metamorphic high-electron-mobility-transistors (HEMT), and the second using 35-nm indium phosphide HEMTs. In this paper, we report the measured gain and noise temperatures of these LNAs.
We are developing an inter-satellite omnidirectional optical communicator (ISOC) that will enable... more We are developing an inter-satellite omnidirectional optical communicator (ISOC) that will enable cross-link communications between spacecraft at Gbps data rates over distances of up to thousands of kilometers in free space. The ISOC will allow superfast cross-links and will be a technology enabler for swarms and formation flying spacecraft. The ISOC under development features a truncated dodecahedron geometry that can hold an array of fast photodiode detectors and gimbal-less MEMS scanning mirrors. The main goals of the ISOC development include: 1) full sky coverage, 2) Gbps data rates and 3) the ability to maintain multiple simultaneous links. We have developed two omnidirectional communicator prototypes capable of full-duplex operation. We are using advanced single-mode laser diodes operating at 850 nm capable of producing hundreds of milliwatts of laser radiation. We are also employing MEMS-based beam steering mirrors, and fast PIN photodiodes to achieve long-range communications. The ultimate goal of the project is to achieve full duplex operation at 1 Gbps data rates over 200 km and slightly lower data rates at longer distances. In this paper we describe the overall ISOC architecture and present the design tradeoffs for gigabit data-rate operation. We also present preliminary NRZ On-Off Keying communications simulation results obtained using our optical link budget model. The ISOC is ideally suited for crosslink communications among small spacecraft, especially for those forming a swarm and/or a constellation. Small spacecraft furnished with ISOC communications systems, should be able to communicate at gigabit per second rates over long distances. This data rate enhancement can allow real-time, global science measurements and/or ultra-high fidelity observations from tens or hundreds of Earth-orbiting satellites, or permit high-bandwidth, direct-to-earth communications for planetary missions.
Omnidirectional Optical Antennas (OOA) with 360 Field of Regard along with full-duplex laser comm... more Omnidirectional Optical Antennas (OOA) with 360 Field of Regard along with full-duplex laser communication capability can play a remarkable role in achieving sophisticated CubeSat mission that can achieve high speed (≥1Gbps), long distance (≥50km) data communication, data relaying among CubeSats and that possesses formation flying ability. In this paper, we discuss miniature optical antenna design optimization techniques using COTS components to facilitate OOA development. In particular, we present challenges involving design tradeoffs among scanning mirror size, scanning angle, transmit beam width, beam divergence, pointing accuracy requirements and component availability in a SWaP-C limited system. We show that to achieve maximum SNR at long distance, the transmit laser beam diameter to mirror diameter ratio needs to be 0.8-0.9. Moreover, we show that the peak intensity varies and can decrease up to 70% over the mirror scanning range depending on transmitter beam size. Furthermore...
Vacuum-tube amplifiers such as klystrons and traveling-wave tubes are the workhorses of high-powe... more Vacuum-tube amplifiers such as klystrons and traveling-wave tubes are the workhorses of high-power microwave radiation generation. At JPL, vacuum tubes are extensively used in ground and flight missions for radar and communications. Vacuum tubes use electron beams as the source of energy to achieve microwave power amplification. Such electron beams operate at high kinetic energies and thus require high voltages to function. In addition, vacuum tubes use compact cavity and waveguide structures that hold very intense radio frequency (RF) fields inside. As the operational frequency is increased, the dimensions of these RF structures become increasingly smaller. As power levels and operational frequencies are increased, the highly intense RF fields inside of the tubes' structures tend to arc and create RF breakdown. In the case of very high-power klystrons, electron interception-also known as body current-can produce thermal runaway of the cavities that could lead to the destruction of the tube. The high voltages needed to power vacuum tubes tend to require complicated and cumbersome power supplies. Consequently, although vacuum tubes provide unmatched high-power microwaves, they tend to arc, suffer from thermal issues, and require failure-prone high-voltage power supplies. In this article, we present a new concept for generating high-power microwaves that we refer to as the Spatial Power Combining Amplifier (SPCA). The SPCA is very compact, requires simpler, lowervoltage power supplies, and uses a unique power-combining scheme wherein power from solid-state amplifiers is coherently combined. It is a two-port amplifier and can be used inline as any conventional two-port amplifier. It can deliver its output power to a coaxial line, a waveguide, a feed, or to any microwave load. A key feature of this new scheme is the use of higher-order-mode microwave structures to spatially divide and combine power. Such higher-order-mode structures have considerably larger cross-sections than comparable klystrons and traveling-wave tube counterparts and thus avoid RF breakdown and thermal issues common to vacuum tubes. We present a basic description of the SPCA mechanism and initial results of an S-band (2.4 GHz) 100-W, 45-dB gain SPCA prototype. We also discuss future X-band (8.4 GHz), Ka-band (32 GHz), and W-band (94 GHz) SPCA designs for both radar and communications applications.
ICOPS 2000. IEEE Conference Record - Abstracts. 27th IEEE International Conference on Plasma Science (Cat. No.00CH37087)
Summary form only given, as follows. Microwave Technologies Incorporated is developing a miniatur... more Summary form only given, as follows. Microwave Technologies Incorporated is developing a miniature cold cathode electron gun (MCEG) prototype as a potential replacement for conventional thermionic cathodes. The MCEG employs Pierce-type geometry and uses microscopic silicon cathode for the generation of a good-quality high-current-density electron beam. We will report on a MCEG proof-of-principle experiment which is designed for the generation
Small satellites and cubesats often have low data transmission rates due to the use of low-gain r... more Small satellites and cubesats often have low data transmission rates due to the use of low-gain radio links in UHF and S bands. These links typically provide up to only 1 Mbps for communication between the ground and LEO, limiting the applications and mission operations of small satellites. Optical communication technology can enable much higher data rates and is rapidly gaining hold for larger satellites, including for crosslinks within SpaceX’s Starlink constellation and upcoming NASA deep space missions. However, it has been difficult to implement on small satellites and cubesats due to the need for precision pointing on the order of arcseconds to align the narrow optical laser beam between terminals--a laser transmitter in LEO may yield a footprint less than 100 meters wide at its receiving ground station. We report the development of a 3U cubesat to demonstrate new optical communication technology that eliminates precision pointing accuracy requirements on the host spacecraft. ...
We are developing a low SWaP (size, weight and power) inter-spacecraft omnidirectional optical co... more We are developing a low SWaP (size, weight and power) inter-spacecraft omnidirectional optical communicator (ISOC) to enable spacecraft swarms. The ISOC employs arrays of lasers telescopes and detectors fitted inside a truncated dodecahedron geometry to provide full sky coverage. Each telescope operates at 850nm and includes a 1W laser diode, collimator, MEMS mirror and steering lens. The photodetectors are strategically arranged around the ISOC body and are used for continuous angle-of-arrival (AOA) calculation of the incoming signals using proprietary AOA algorithms. The ISOC provides full sky coverage (4π steradians) and will be able to maintain multiple gigabit links simultaneously. In this paper we will present the latest experimental results obtained with the ISOC including high data rate communication tests between 2 ISOCs. We will also present results of our swarm simulator that includes 4 ISOCs mounted on computer-controlled moving platforms. Lastly, we will present design details of a technology demonstration mission concept for validating the ISOC as well as examples of future swarm missions that could be enabled by this technology.
IEEE International Conference on Plasma Science, 2000
Summary form only given. We report on the status of a very compact, high efficiency harmonic ampl... more Summary form only given. We report on the status of a very compact, high efficiency harmonic amplifier (HARA) prototype experiment. In this experiment, a 6 kV 200 mA pencil electron beam undergoes circular scanning-modulation inside a short microwave resonator operating in circular polarization at 5.85 GHz. A 35 GHz output cavity operating at the 6th harmonic of the drive frequency
Terahertz for Military and Security Applications II, 2004
Microwave Technologies is developing a revolutionary miniature terahertz traveling-wave microtube... more Microwave Technologies is developing a revolutionary miniature terahertz traveling-wave microtube (TTM) that will provide sub-millimeter wave radiation for many civilian and military applications. This new concept uses a dielectric microtube in conjunction with a microscopic electron beam. The electron beam is produced by a single micron-sized emitter, which lies underneath the microtube to produce high-power terahertz electromagnetic radiation. The TTM should be easily fabricated using state-of-the-art solid-state technology, and will be a pioneering step towards combining vacuum tube technology with solid-state microfabrication technology. Some of the applications for these exciting new devices include terahertz high-resolution radar, THz chemical and biological sensing, commercial THz line-of-sight networking and ultrahigh-speed computers. A key application of the device under development will be as a miniature terahertz source for biological and chemical spectroscopy. We present detailed numerical and computational analysis of this concept. We also present initial experimental testing of a dielectric microtube designed to operate at 0.1 THz. Once successfully developed, TTMs will be the basis for a new generation of high power terahertz sources capable of producing ultrahigh frequency radiation with high efficiency in an amazingly compact and lightweight package.
We are developing a compact high-frequency electron buncher for applications in accelerator and m... more We are developing a compact high-frequency electron buncher for applications in accelerator and microwave tubes. This electron buncher uses a conventional Pierce-type electron gun with a gated field-emitter-array cathode for the production of short, 10kV, 100mA electron bunches. The width of the electron bunches can be adjusted to be a small part (10parameters. We have tested these cold cathodes in
The 33rd IEEE International Conference on Plasma Science, 2006. ICOPS 2006. IEEE Conference Record - Abstracts., 2006
Summary form only given. We are carrying out the development of a compact W-band dielectric trave... more Summary form only given. We are carrying out the development of a compact W-band dielectric traveling-wave tube (DTWT) amplifier. The DTWT amplifier is based on the interaction between a magnetized electron beam and the fields of a traveling wave inside a very compact dielectric waveguide. A high permittivity dielectric waveguide is used to slow down the wave and replaces the less efficient helix structures used in conventional traveling-wave tubes. A novel approach in this development is the use of micromachining techniques for the fabrication of the various components of this amplifier. We will present experimental results of RF and beam transport experiments along the DTWT circuit. The DTWT should be capable of producing millimeter-wave radiation for future military battlespace applications
IEEE Conference Record - Abstracts. 2005 IEEE International Conference on Plasma Science, 2005
Summary form only given. We have begun the development of a compact W-band dielectric traveling-w... more Summary form only given. We have begun the development of a compact W-band dielectric traveling-wave tube (DTWT) prototype. The DTWT amplifier is based on the interaction between a well-collimated electron beam and the electromagnetic fields of a traveling wave inside a very compact dielectric waveguide. The dielectric waveguide is used to slow down the wave and replaces the less efficient helix structures used in conventional traveling-wave tubes. A novel approach in this development is the use of micromachining techniques for the fabrication of the various components of this amplifier. We will present design considerations for a 94 GHz, 10-watt amplifier. The DTWT should be capable of replacing conventional traveling-wave tubes in telecommunication systems for future space applications by offering substantial improvements in size, weight, and especially efficiency over its counterparts
Creation of a rotating wave field in a high-Q resonator usually requires the resonator to be tune... more Creation of a rotating wave field in a high-Q resonator usually requires the resonator to be tuned to compensate for manufacturing errors. The tuning of a rotating wave resonator is more complicated than that of a common resonator. A theory of tuning rotating wave resonators and a procedure for efficiently carrying out this tuning is presented in this paper, along with the authors’ experience in tuning a rotating TM110 mode in a 1.28 GHz microwave resonator.
2007 IEEE International Vacuum Electronics Conference, 2007
Summary form only given.This paper presents that the microwave technologies is developing a compa... more Summary form only given.This paper presents that the microwave technologies is developing a compact two-cavity amplifier that uses a rugged carbon-nanotube cold-cathode to produce microwave radiation with very high efficiency. The entire RF circuit and electron gun have already been built and are currently under testing. We will present experimental results of electron beam generation and transport along the C-band RF circuit. Initial microwave amplification results will be also reported. This new amplifier should be capable of replacing conventional traveling- wave tubes in future radar and communication systems by offering substantial improvements in size, weight, and especially efficiency over its counterparts. This work is supported by the missile defense agency under the small business innovation research program.
In this paper, we describe a miniature power-combiner for monolithic millimeter-wave integrated c... more In this paper, we describe a miniature power-combiner for monolithic millimeter-wave integrated circuit (MMIC) chips using spatial power-combining with cavity modes. We have designed GaN MMIC power amplifier chips for 94 GHz, and illustrate the concept of the W-Band Spatial Power Combining Amplifier (WSPCA). Using 1 Watt, 94 GHz MMIC chips in a two-way cavity mode combiner, we were able to achieve 2 Watts of output power with 9 dB gain and 15 % PAE. This technique could be extended to high power MMICs and larger numbers of chips to achieve higher output power in a compact size. Current applications include earth science radar, and may be extended to other applications requiring wider bandwidth.
The Deployable Optical Receive Aperture (DORA), a new technology being developed jointly between ... more The Deployable Optical Receive Aperture (DORA), a new technology being developed jointly between Jet Propulsion Laboratory (JPL) and Arizona State University (ASU), is based on deploying arrays of fast optical detectors to create large receive apertures and seeks to achieve gigabit connectivity at distances of thousands of kilometers. Small spacecraft forming the LunaNet communications network and equipped with optical communications systems, such as the proposed DORA aperture, should be able to communicate at Gigabit per second rates over long distances. This data rate enhancement can allow gigabit per second connectivity between lunar assets (astronauts, rovers, instruments) and the lunar gateway. Under sponsorship of NASA's Small Spacecraft Technology Program (SSTP), JPL is deploying the DORA payload and ASU is developing a 3U CubeSat for a follow on LEO mission to demonstrate DORA's capabilities. The basic DORA payload consists of 5 detector panels, a transmitting telescope and processing units. Each detector panel contains dozens of power-combined detectors to mimic a large optical receive aperture. The total receive aperture of DORA is provided by sum of the effective detecting area of the 5 panels. The transmit telescope includes a 200mW, 850nm laser and a voice-coil fast steering mirror (FSM). The resulting DORA terminal should be able to provide duplex connectivity at rates up to 1 gigabit per second at the distances of interest. We have designed the entire DORA payload and plan to present the test results of our DORA engineering model. These results include angle-of-arrival, data rate and bit error rate measurements.
We have implemented a single wideband receiver package that could cover the 8 to 48 GHz frequency... more We have implemented a single wideband receiver package that could cover the 8 to 48 GHz frequency range of the ngVLA. The current JVLA covers this frequency range employing five distinct receiver packages. We estimate that reducing the number of receiving systems required to cover the full frequency range should reduce operating costs. The receiver package we developed consists of a quad-ridge feed horn, low-noise amplifiers (LNA), and a down-converter to analog intermediate frequencies. Both the feedhorn and the LNA are cryogenically cooled. On the LNA front we pursued two 8-48 GHz MMIC designs, the first using 70-nm gallium arsenide, metamorphic high-electron-mobility-transistors (HEMT), and the second using 35-nm indium phosphide HEMTs. In this paper, we report the measured gain and noise temperatures of these LNAs.
We are developing an inter-satellite omnidirectional optical communicator (ISOC) that will enable... more We are developing an inter-satellite omnidirectional optical communicator (ISOC) that will enable cross-link communications between spacecraft at Gbps data rates over distances of up to thousands of kilometers in free space. The ISOC will allow superfast cross-links and will be a technology enabler for swarms and formation flying spacecraft. The ISOC under development features a truncated dodecahedron geometry that can hold an array of fast photodiode detectors and gimbal-less MEMS scanning mirrors. The main goals of the ISOC development include: 1) full sky coverage, 2) Gbps data rates and 3) the ability to maintain multiple simultaneous links. We have developed two omnidirectional communicator prototypes capable of full-duplex operation. We are using advanced single-mode laser diodes operating at 850 nm capable of producing hundreds of milliwatts of laser radiation. We are also employing MEMS-based beam steering mirrors, and fast PIN photodiodes to achieve long-range communications. The ultimate goal of the project is to achieve full duplex operation at 1 Gbps data rates over 200 km and slightly lower data rates at longer distances. In this paper we describe the overall ISOC architecture and present the design tradeoffs for gigabit data-rate operation. We also present preliminary NRZ On-Off Keying communications simulation results obtained using our optical link budget model. The ISOC is ideally suited for crosslink communications among small spacecraft, especially for those forming a swarm and/or a constellation. Small spacecraft furnished with ISOC communications systems, should be able to communicate at gigabit per second rates over long distances. This data rate enhancement can allow real-time, global science measurements and/or ultra-high fidelity observations from tens or hundreds of Earth-orbiting satellites, or permit high-bandwidth, direct-to-earth communications for planetary missions.
Omnidirectional Optical Antennas (OOA) with 360 Field of Regard along with full-duplex laser comm... more Omnidirectional Optical Antennas (OOA) with 360 Field of Regard along with full-duplex laser communication capability can play a remarkable role in achieving sophisticated CubeSat mission that can achieve high speed (≥1Gbps), long distance (≥50km) data communication, data relaying among CubeSats and that possesses formation flying ability. In this paper, we discuss miniature optical antenna design optimization techniques using COTS components to facilitate OOA development. In particular, we present challenges involving design tradeoffs among scanning mirror size, scanning angle, transmit beam width, beam divergence, pointing accuracy requirements and component availability in a SWaP-C limited system. We show that to achieve maximum SNR at long distance, the transmit laser beam diameter to mirror diameter ratio needs to be 0.8-0.9. Moreover, we show that the peak intensity varies and can decrease up to 70% over the mirror scanning range depending on transmitter beam size. Furthermore...
Vacuum-tube amplifiers such as klystrons and traveling-wave tubes are the workhorses of high-powe... more Vacuum-tube amplifiers such as klystrons and traveling-wave tubes are the workhorses of high-power microwave radiation generation. At JPL, vacuum tubes are extensively used in ground and flight missions for radar and communications. Vacuum tubes use electron beams as the source of energy to achieve microwave power amplification. Such electron beams operate at high kinetic energies and thus require high voltages to function. In addition, vacuum tubes use compact cavity and waveguide structures that hold very intense radio frequency (RF) fields inside. As the operational frequency is increased, the dimensions of these RF structures become increasingly smaller. As power levels and operational frequencies are increased, the highly intense RF fields inside of the tubes' structures tend to arc and create RF breakdown. In the case of very high-power klystrons, electron interception-also known as body current-can produce thermal runaway of the cavities that could lead to the destruction of the tube. The high voltages needed to power vacuum tubes tend to require complicated and cumbersome power supplies. Consequently, although vacuum tubes provide unmatched high-power microwaves, they tend to arc, suffer from thermal issues, and require failure-prone high-voltage power supplies. In this article, we present a new concept for generating high-power microwaves that we refer to as the Spatial Power Combining Amplifier (SPCA). The SPCA is very compact, requires simpler, lowervoltage power supplies, and uses a unique power-combining scheme wherein power from solid-state amplifiers is coherently combined. It is a two-port amplifier and can be used inline as any conventional two-port amplifier. It can deliver its output power to a coaxial line, a waveguide, a feed, or to any microwave load. A key feature of this new scheme is the use of higher-order-mode microwave structures to spatially divide and combine power. Such higher-order-mode structures have considerably larger cross-sections than comparable klystrons and traveling-wave tube counterparts and thus avoid RF breakdown and thermal issues common to vacuum tubes. We present a basic description of the SPCA mechanism and initial results of an S-band (2.4 GHz) 100-W, 45-dB gain SPCA prototype. We also discuss future X-band (8.4 GHz), Ka-band (32 GHz), and W-band (94 GHz) SPCA designs for both radar and communications applications.
ICOPS 2000. IEEE Conference Record - Abstracts. 27th IEEE International Conference on Plasma Science (Cat. No.00CH37087)
Summary form only given, as follows. Microwave Technologies Incorporated is developing a miniatur... more Summary form only given, as follows. Microwave Technologies Incorporated is developing a miniature cold cathode electron gun (MCEG) prototype as a potential replacement for conventional thermionic cathodes. The MCEG employs Pierce-type geometry and uses microscopic silicon cathode for the generation of a good-quality high-current-density electron beam. We will report on a MCEG proof-of-principle experiment which is designed for the generation
Small satellites and cubesats often have low data transmission rates due to the use of low-gain r... more Small satellites and cubesats often have low data transmission rates due to the use of low-gain radio links in UHF and S bands. These links typically provide up to only 1 Mbps for communication between the ground and LEO, limiting the applications and mission operations of small satellites. Optical communication technology can enable much higher data rates and is rapidly gaining hold for larger satellites, including for crosslinks within SpaceX’s Starlink constellation and upcoming NASA deep space missions. However, it has been difficult to implement on small satellites and cubesats due to the need for precision pointing on the order of arcseconds to align the narrow optical laser beam between terminals--a laser transmitter in LEO may yield a footprint less than 100 meters wide at its receiving ground station. We report the development of a 3U cubesat to demonstrate new optical communication technology that eliminates precision pointing accuracy requirements on the host spacecraft. ...
We are developing a low SWaP (size, weight and power) inter-spacecraft omnidirectional optical co... more We are developing a low SWaP (size, weight and power) inter-spacecraft omnidirectional optical communicator (ISOC) to enable spacecraft swarms. The ISOC employs arrays of lasers telescopes and detectors fitted inside a truncated dodecahedron geometry to provide full sky coverage. Each telescope operates at 850nm and includes a 1W laser diode, collimator, MEMS mirror and steering lens. The photodetectors are strategically arranged around the ISOC body and are used for continuous angle-of-arrival (AOA) calculation of the incoming signals using proprietary AOA algorithms. The ISOC provides full sky coverage (4π steradians) and will be able to maintain multiple gigabit links simultaneously. In this paper we will present the latest experimental results obtained with the ISOC including high data rate communication tests between 2 ISOCs. We will also present results of our swarm simulator that includes 4 ISOCs mounted on computer-controlled moving platforms. Lastly, we will present design details of a technology demonstration mission concept for validating the ISOC as well as examples of future swarm missions that could be enabled by this technology.
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Papers by Jose Velazco