A measuring bridge (1) provides a first matching pad (2), a second matching pad (3) and a third matching pad (4), wherein all matching pads (2, 3, 4) comprise at least three resistors (2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3, 4.sub.1, 4.sub.2, 4.sub.3) which are arranged in a T-structure. A second resistor (3.sub.2) of the second matching pad (3) is connected to a second resistor (2.sub.2) of the first matching pad (2), and a third resistor (4.sub.3) of the third matching pad (4) is connected to a third resistor (2.sub.3) of the first matching pad (2). A second resistor (4.sub.2) of the third matching pad (4) can be connected to a device under test (7). A third resistor (3.sub.3) of the second matching pad (3) can be connected to a calibration standard (5), and a first resistor (3.sub.1, 4.sub.1) of the second and the third matching pad (3, 4) are connected in each case to a signal input of an element (11) which suppresses a common-mode component on its two signal inputs.

A measuring bridge (1) provides a first matching pad (2), a second matching pad (3) and a third matching pad (4), wherein all matching pads (2, 3, 4) comprise at least three resistors (2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3, 4.sub.1, 4.sub.2, 4.sub.3) which are arranged in a T-structure. A second resistor (3.sub.2) of the second matching pad (3) is connected to a second resistor (2.sub.2) of the first matching pad (2), and a third resistor (4.sub.3) of the third matching pad (4) is connected to a third resistor (2.sub.3) of the first matching pad (2). A second resistor (4.sub.2) of the third matching pad (4) can be connected to a device under test (7). A third resistor (3.sub.3) of the second matching pad (3) can be connected to a calibration standard (5), and a first resistor (3.sub.1, 4.sub.1) of the second and the third matching pad (3, 4) are connected in each case to a signal input of an element (11) which suppresses a common-mode component on its two signal inputs.

An inductive-capacitive (LC) wireless sensor for the detection of toxic heavy metal ions includes inductors and interdigitated electrodes (IDE) in planar form. The sensor may be fabricated by screen printing silver (Ag) ink onto a flexible polyethylene-terephthalate (PET) substrate to form a metallization layer. Palladium nanoparticles (Pd NP) may be drop casted onto the IDEs to form a sensing layer. The resonant frequency of the LC sensor may be remotely monitored by measuring the reflection coefficient (S.sub.11) of a detection coil (planar inductor). The resonant frequency of the LC sensor changes with varying concentrations of heavy metals such as mercury (Hg.sup.2+) and lead (Pb.sup.2+) ions. Changes in the resonant frequency may be used to detect the presence and/or concentration of heavy metal ions.

An inductive-capacitive (LC) wireless sensor for the detection of toxic heavy metal ions includes inductors and interdigitated electrodes (IDE) in planar form. The sensor may be fabricated by screen printing silver (Ag) ink onto a flexible polyethylene-terephthalate (PET) substrate to form a metallization layer. Palladium nanoparticles (Pd NP) may be drop casted onto the IDEs to form a sensing layer. The resonant frequency of the LC sensor may be remotely monitored by measuring the reflection coefficient (S.sub.11) of a detection coil (planar inductor). The resonant frequency of the LC sensor changes with varying concentrations of heavy metals such as mercury (Hg.sup.2+) and lead (Pb.sup.2+) ions. Changes in the resonant frequency may be used to detect the presence and/or concentration of heavy metal ions.

Methods, apparatus, and computer program products using spectrum analysis or cross correlation techniques to discriminate against interference. These approaches are straight forward if both the forward and reflected signals contain complex or quadrature (I and Q) samples. But, if only single axis samples are available as is often the case to reduce the sampling rate, the resulting samples could represent the I component, the Q component or, more likely, some combination of the two. This generally requires some type of time alignment procedure to ensure proper phase. Assuming that the transmitted signal exists in complex form, this signal can be mathematically rotated in phase and then single axis sampled for comparison against the single axis reflected signal. If the rotation is done over equally spaced intervals that spans one complete cycle, the average of the absolute value all such return loss ratios will approach the actual return loss ratio and the interference will be suppressed. The resultant can be compared to a threshold value and trigger an alarm.

A microwave (MW) system includes an object support adapted to support an object, a MW transmitter, a MW receiver, an outer rotation unit, an inner rotation unit, a controller and a computation processor. The outer rotation unit includes an outer ring, having a ring shape, with an outer ring mount, upon which one of either an antenna of the MW transmitter or an antenna of the MW receiver is mounted. The inner rotation unit comprises an inner ring, having a ring shape, with an inner ring mount, upon which the other of an antenna of the MW transmitter or an antenna of the MW receiver is mounted. The controller is configured to independently control both the rotation of the inner ring and the outer ring. The computation processor is configured to receive data including MW data representative of MW scattered field detected by the MW receiver.

A self-calibrating transmission line resonator oscillating driver apparatus, including: a first output driver module configured to transmit a first forward signal along a transmission line; a second output driver module configured to transmit a second forward signal along the transmission line; a first reflection detection module configured to detect a first return signal of the first forward signal reflected along the transmission line; and a second reflection detection module configured to detect a second return signal of the second forward signal reflected along the transmission line; wherein, when the first reflection detection module detects the first return signal of the first forward signal reflected along the second direction of the transmission line, providing a signal to i) change a power state of the first output driver module to an off-power state and to ii) change a power state of the second output driver module to an on-power state.

A self-calibrating transmission line resonator oscillating driver apparatus, including: a first output driver module configured to transmit a first forward signal along a transmission line; a second output driver module configured to transmit a second forward signal along the transmission line; a first reflection detection module configured to detect a first return signal of the first forward signal reflected along the transmission line; and a second reflection detection module configured to detect a second return signal of the second forward signal reflected along the transmission line; wherein, when the first reflection detection module detects the first return signal of the first forward signal reflected along the second direction of the transmission line, providing a signal to i) change a power state of the first output driver module to an off-power state and to ii) change a power state of the second output driver module to an on-power state.

Each of a plurality electronic circuit devices fixed to a structural component of a physical structure can be scanned a first time, using a radio frequency (RF) scanner to receive, from each of the plurality of electronic circuit devices, first data indicating a first measured electrical impedance of a respective conductor connected to the electronic circuit device and an identifier assigned to the electronic circuit device. For each of the plurality of electronic circuit devices, the first data indicating the first measured electrical impedance and the identifier assigned to the electronic circuit device can be stored to a first memory. The first data indicating the first measured electrical impedance and the identifier for each of the electronic devices can form a baseline measurement of the electronic circuit devices.

A reflectometer for use in measuring scattering (S-)parameters for a device under test (DUT) includes a test port, a radio frequency (RF) output signal source, and a local oscillator (LO) signal. The LO signal is used to downconvert the RF output signal to an incident IF signal. The reflectometer is useable as a first reflectometer with a second reflectometer such that the first and second reflectometers are phase synchronized by a synchronization signal. Phase and magnitude of transmission S-parameters of the DUT are measurable when the first reflectometer is used with the second reflectometer. The roles of the first and second reflectometers are reversible to allow for measurement of forward and reverse parameters. Further, the synchronization signal can be provided by one reflectometer to the other (or both can receive a separately generated synchronization signal) via a wire or fiber optic cable, for example, or via a wireless connection.