A low radio frequency electro-mechanical load pull impedance tuner uses four rotary, remotely controlled variable shunt capacitors and three fixed series transmission lines to create up to 10.sup.8 independently controllable impedance states at each frequency covering the entire Smith chart in the frequency range between 1 and 10 MHz; the capacitors and control motors and gear are immersed in high epsilon dielectric fluid inside individual sealed containers. Appropriate Error Function-based optimization algorithms, allow fast impedance tuning at the fundamental frequency at the output of DUT's operated in high gain compression. Stepper motors, drivers and control software are used to remotely control the variable shunt capacitors of the tuner and allow it to be automated, pre-calibrated and used in an automated load pull measuring setup.

A system for passive microwave remote sensing using at least one microwave radiometer includes a fixed body portion and a mobile body portion. The mobile body portion is configured for rotatably coupling with the fixed body portion for rotation about a rotation axis. The mobile body portion is configured for supporting the microwave radiometer therein such that the microwave radiometer rotates about the rotation axis when the mobile body portion is rotated about the rotation axis such that a polarization axis of the radiometer is aligned with an earth axis. The fixed body portion includes a motor mechanism for effecting rotation of the mobile body portion. In an embodiment, the mobile body portion includes a plurality of body section, each body section being configured for supporting a microwave radiometer therein. In another embodiment, each one of the plurality of body sections is configured to be interchangeably coupled with each other.

The focus of the teachings is on using Compact ferrite antenna to detect the motion of metal objects using a very low frequency (VLF) square wave, propagated between a pair of compact ferrite-particle dielectric-core RWA antennas in free space. The two salient features in the signal are observed; both of which are characteristic of Brillouin-precursor propagation: (1) a temporal Bessel-like waveform; and (2) an algebraic, rather than exponential, attenuation with distance over three meters. The key element teaching shows pair of source and detector antenna enables the detection of metals (weapon gun, knife) on a person or package between the ferrite-particle dielectric-core antennas-source (S) and detector (D) pairs or arrays of S-D tractor. The detection consisted of a change in the amplitude of the Bessel-like waveform of the received signal for security system to detect weapons.

Various examples are provided related to anisotropic constitutive parameters (ACPs) that can be used to launch Zenneck surface waves. In one example, among others, an ACP system includes an array of ACP elements distributed above a medium such as, e.g., a terrestrial medium. The array of ACP elements can include one or more horizontal layers of radial resistive artificial anisotropic dielectric (RRAAD) elements positioned in one or more orientations above the terrestrial medium. The ACP system can include vertical lossless artificial anisotropic dielectric (VLAAD) elements distributed above the terrestrial medium in a third orientation perpendicular to the horizontal layer or layers. The ACP system can also include horizontal artificial anisotropic magnetic permeability (HAAMP) elements distributed above the terrestrial medium. The array of ACP elements can be distributed about a launching structure, which can be excited with an electromagnetic field to facilitate the launch of a Zenneck surface wave.

A vector network analyzer configured to analyze a high-frequency signal received is described. The vector network analyzer includes three or more reflectometers, each reflectometer operating at a respective frequency range and having a first terminal and a second terminal. The reflectometers are connected with each other in series such that a combined frequency range of the vector network analyzer is established. A first reflectometer is connected to one of a load or a signal source via its first terminal. A last reflectometer is connected to a test port via its second terminal. At least two reflectometers are interconnected with each other by an interposed frequency selective absorptive filter.

A measuring carrier for position-resolved meteorological determination of a measurement variable dependent on the dielectric permittivity of a device under test. The measuring carrier has a supporting means comprising a measuring surface, to which the device under test can be applied, and a measuring transmission line which entirely or partially forms the measuring surface and comprises a multiplicity of transmission line cells for the purpose of transmitting a radio-frequency measurement signal which can be injected at the input port. The measuring surface is structured in a cellular manner, wherein each of the transmission line cells has a cell-individual propagation constant with respect to the radio-frequency measurement signal in a state free of a device under test. This constant differs from the respective cell-individual constants of the other transmission line cells.

A measuring carrier for position-resolved meteorological determination of a measurement variable dependent on the dielectric permittivity of a device under test. The measuring carrier has a supporting means comprising a measuring surface, to which the device under test can be applied, and a measuring transmission line which entirely or partially forms the measuring surface and comprises a multiplicity of transmission line cells for the purpose of transmitting a radio-frequency measurement signal which can be injected at the input port. The measuring surface is structured in a cellular manner, wherein each of the transmission line cells has a cell-individual propagation constant with respect to the radio-frequency measurement signal in a state free of a device under test. This constant differs from the respective cell-individual constants of the other transmission line cells.

A sampling circuit includes: a first transmission line that transmits an input signal; a second transmission line that transmits a clock signal; and a plurality of sample-hold circuits that are connected to the first and second transmission lines at a constant line distance, wherein the first transmission line transmits the input signal at a first propagation time for each of the line distances, and the second transmission line transmits the clock signal at a second propagation time that is a sum of a preset sampling interval and the first propagation time for each of the line distances.

A sampling circuit includes: a first transmission line that transmits an input signal; a second transmission line that transmits a clock signal; and a plurality of sample-hold circuits that are connected to the first and second transmission lines at a constant line distance, wherein the first transmission line transmits the input signal at a first propagation time for each of the line distances, and the second transmission line transmits the clock signal at a second propagation time that is a sum of a preset sampling interval and the first propagation time for each of the line distances.

An S-parameter of a reference impedance is determined and converted to a desired mode of operation. Example modes of operation include a single-ended input output mode, a differential input output mode, and a common input output mode. The complex values of the impedance at each port as a function of frequency can be computed using the novel closed-form quadratic S-parameter equation which utilizes the concept of matched networks by setting the reflections and re-reflections to zero through S-parameter renormalization. Using the S-parameter renormalization, the insertion loss corresponding to zero reflections and re-reflections is calculated. Based on the determination of the matching impedance used to reduce the reflections and re-reflections to zero, a parameter of a circuit comprising the network may be modified to reduce noise.