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Daniel J. Hoppe

Other affiliations: Jet Propulsion Laboratory
Bio: Daniel J. Hoppe is an academic researcher from California Institute of Technology. The author has contributed to research in topic(s): Antenna (radio) & NASA Deep Space Network. The author has an hindex of 16, co-authored 77 publication(s) receiving 1046 citation(s). Previous affiliations of Daniel J. Hoppe include Jet Propulsion Laboratory.
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01 Apr 2002
Abstract: A tunable nanomechanical oscillator device and system is provided. The nanomechanical oscillator device comprising at least one nanoresonator, such as a suspended nanotube, designed such that injecting charge density into the tube (e.g. by applying a capacitively-cuopled voltage bias) changes the resonant frequency of the nanotube, and where exposing the resonator to an RF bias induces oscillitory movement in the suspended portion of the nanotube, forming a nanoscale resonator, as well as a force sensor when operated in an inverse mode. A method of producing an oriented nanoscale resonator structure with integrated electrodes is also provided.

209 citations

01 Apr 2002
Abstract: A tunable nanomechanical filter system (10) comprising an array of nanofeatures (18), such as nanotubes, where the nanofeatures (18) are in signal communication with means for inducing a difference in charge density in the nanofeature (18) such that the mechanical resonant frequency of the nanofeature (18) can be tuned, and where the nanofeature (18) is in signal communication with a waveguide (14) or other RF bias conduit such that an RF signal having a frequency corresponding to the mechanical resonant frequency of the array will couple to the array thereby inducing resonant motion in the array of nanofeatures (18), and subsequently coupling to an output waveguide (16), forming a nanoscale RF filter (10) is provided. A method of producing a nanoscale RF filter (10) structure controllably positioned and oriented with a waveguide (14/16) and integrated electrodes (20) is also provided.

100 citations

Journal ArticleDOI
Abstract: This article describes the development of a deployable high-gain antenna (HGA) for the proposed Mars Cube One (MarCO) CubeSat mission to Mars. The antenna is a new folded-panel reflectarray (FPR) designed to fit on a 6U (10 ? 20 ? 34 cm3) CubeSat bus and support 8.425-GHz Mars-to-Earth telecommunications. The FPR provides a gain of 29.2 dBic with right-hand circular polarization (RHCP). Small stowage volume is a key advantage of the FPR design, as it only consumes ~4% of the usable spacecraft payload volume with a mass of less than 1 kg.

96 citations

Journal ArticleDOI
Abstract: A method of using low-loss waveguide septum combiners is developed into a high-power -band (31-36 GHz) amplifier producing 50 W at 33 GHz (Ka-band) using 32 low-power (>2 W) solid-state amplifier modules. By using low-loss waveguide combining and a packaged monolithic microwave integrated circuit with a low-loss microstrip-to-waveguide launcher, the output loss is minimized, allowing for the overall power-combining efficiency to remain high, 80% (average insertion loss of combiner < 0.7 dB and average insertion loss of launcher <0.3 dB) over 31-36 GHz. In the past, lower power-combining efficiencies have limited the number of modules that can be combined at -band, and hence, have limited the power output. The approach demonstrated in this paper, with high power-combining efficiency, allows a very large number (32) of solid-state amplifier modules to be combined to produce high powers. Greater than 50 W was demonstrated with low power modules, but even higher powers 120 W are possible. The current approach is based on corporate combining, using low-loss waveguide septum combiners that provide isolation, maintaining the true graceful degradation of a modular solid-state amplifier system.

75 citations

Proceedings ArticleDOI
17 May 2015
Abstract: Two novel high gain deployable reflectarray antennas to support CubeSat telecommunications are described and compared with other high gain CubeSat antenna technologies. The first reflectarray is the Integrated Solar Array and Reflectarray Antenna (ISARA), a K/Ka-band antenna that also incorporates a dense packing of solar cells used to provide electrical power for the spacecraft. The second is an X-band reflectarray designed to provide a bent pipe telecom link. These reflectarrays are ideal for CubeSat applications because they require negligible stowed volume and impose a modest mass increase. The antenna designs and measured performance results are presented.

63 citations

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16 Jul 2002
Abstract: The present invention relates generally to sub-microelectronic circuitry, and more particularly to nanometer-scale articles, including nanoscale wires which can be selectively doped at various locations and at various levels. In some cases, the articles may be single crystals. The nanoscale wires can be doped, for example, differentially along their length, or radially, and either in terms of identity of dopant, concentration of dopant, or both. This may be used to provide both n-type and p-type conductivity in a single item, or in different items in close proximity to each other, such as in a crossbar array. The fabrication and growth of such articles is described, and the arrangement of such articles to fabricate electronic, optoelectronic, or spintronic devices and components. For example, semiconductor materials can be doped to form n-type and p-type semiconductor regions for making a variety of devices such as field effect transistors, bipolar transistors, complementary inverters, tunnel diodes, light emitting diodes, sensors, and the like.

598 citations

Journal ArticleDOI
Abstract: Spurred by the discovery of carbon nanotubes in 1991 and the subsequent nanotechnology revolution, there has been a marked increase in the volume of scientific and engineering literature dealing with various aspects of the vibratory behavior of carbon nanotubes and their composites in the last few years. This paper is an attempt to present a coherent yet concise review of as many of these publications as possible. The major topics covered in this review are modeling and simulation of vibrating nanotubes, studies of nanomechanical resonators and oscillators, the use of vibration measurements to characterize nanotube mechanical properties, nanotube augmentation of dynamic structural properties of composites, vibrations of nanotube-based sensors and actuators, sonication of nanotube-reinforced polymer resins, Raman scattering from nanotubes, and high frequency wave–nanotube interactions. Summaries of both theoretical and experimental studies are included, along with key conclusions and recommendations from these studies.

481 citations

04 Oct 2006
Abstract: A bulk-doped semiconductor that is at least one of the following: a single crystal, an elongated and bulk-doped semiconductor that, at any point along its longitudinal axis, has a largest cross-sectional dimension less than 500 nanometers, and a free-standing and bulk-doped semiconductor with at least one portion having a smallest width of less than 500 nanometers. Such a semiconductor may comprise an interior core comprising a first semiconductor; and an exterior shell comprising a different material than the first semiconductor. Such a semiconductor may be elongated and may have, at any point along a longitudinal section of such a semiconductor, a ratio of the length of the section to a longest width is greater than 4:1, or greater than 10:1, or greater than 100:1, or even greater than 1000:1. At least one portion of such a semiconductor may a smallest width of less than 200 nanometers, or less than 150 nanometers, or less than 100 nanometers, or less than 80 nanometers, or less than 70 nanometers, or less than 60 nanometers, or less than 40 nanometers, or less than 20 nanometers, or less than 10 nanometers, or even less than 5 nanometers. Such a semiconductor may be a single crystal and may be free-standing. Such a semiconductor may be either lightly n-doped, heavily n-doped, lightly p-doped or heavily p-doped. Such a semiconductor may be doped during growth. Such a semiconductor may be part of a device, which may include any of a variety of devices and combinations thereof, and a variety of assembling techniques may be used to fabricate devices from such a semiconductor. Two or more of such a semiconductors, including an array of such semiconductors, may be combined to form devices, for example, to form a crossed p-n junction of a device. Such devices at certain sizes may exhibit quantum confinement and other quantum phenomena, and the wavelength of light emitted from one or more of such semiconductors may be controlled by selecting a width of such semiconductors. Such semiconductors and device made therefrom may be used for a variety of applications.

460 citations

Journal ArticleDOI
Abstract: Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.

452 citations

01 Oct 2002
Abstract: Starting from the equivalence theorem any composite metallic and dielectric structure can be analyzed by using SIE (surface integral equations). Such integral equations are usually solved by MoM (method of moments). Most of the existing MoM methods for solving SIE are developed for BORs (bodies of revolution). There are only few such methods that can handle structures of arbitrary shape. These methods use sub-domain basis functions defined over triangles, requiring a very large number of unknowns even for the simplest problems. This paper presents a new MoM method for electromagnetic modeling of composite metallic and dielectric structures. The method uses entire-domain basis functions defined over bilinear surfaces, resulting in a remarkably small number of unknowns.

428 citations

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Author's H-index: 16

No. of papers from the Author in previous years