Abstract: A method for measuring s-parameters of an N-port device under test (DUT), using an N-port test fixture and a network analyzer. The method includes: measuring calibration errors of the N-port test fixture using a reduced set of N/2 calibration standards; measuring calibration errors due to the network analyzer by calibrating only the network analyzer using analyzer-only calibration standards; isolating test fixture s-parameters errors using results of the analyzer-only calibration standards measurement and the N-port test fixture calibration standard measurement; measuring the s-parameters errors of the DUT; and correcting the s-parameters errors of the DUT corresponding to the isolated test fixture s-parameters errors and the calibration errors of the network analyzer.

Abstract: A method for measuring s-parameters of an N-port device under test (DUT), using an N-port test fixture and a network analyzer. The method includes: measuring calibration errors of the N-port test fixture using a reduced set of N/2 calibration standards; measuring calibration errors due to the network analyzer by calibrating only the network analyzer using analyzer-only calibration standards; isolating test fixture s-parameters errors using results of the analyzer-only calibration standards measurement and the N-port test fixture calibration standard measurement; measuring the s-parameters errors of the DUT; and correcting the s-parameters errors of the DUT corresponding to the isolated test fixture s-parameters errors and the calibration errors of the network analyzer.

Abstract: A phased array radar system employs programmable microelectromechanical (MEM) switches and transmission lines to provide true time delays or phase shifts in order to steer the array beam. The array includes an excitation signal source, a power division network for dividing the excitation signal into a plurality of excitation signal components, a plurality of programmable time delay/phase shift circuits including the transmission lines and MEM switches, and a plurality of radiating elements. An adaptive controller provides the control signals to set the MEM switches and select the time delay/phase shift through each time delay/phase shift circuit, thereby steering the array beam to a desired direction.

Abstract: A minimum phase shift microwave attenuator circuit, providing very low insertion phase change with changing attenuation levels. Three PIN diodes are biased in parallel from a common node. The PIN diodes are held at zero or reverse bias for the "no attenuation" state, and are made slightly lossy to produce the attenuation state. In the attenuation state, the PIN diodes are utilized as current controlled lossy capacitors which change resistance with applied bias, but maintain constant capacitance, thereby providing low insertion phase deviation across wide attenuation levels.

Abstract: An adjustable microwave power divider circuit (50), providing the capability of adjusting the power division ratio after the device has been fabricated. The device includes three 90 degree transmission line networks (60, 70, 80) incorporating open transmission line stubs (66, 76, 86), two networks (70, 80) as power division networks, and the third network (60) as an input impedance matching network. A series isolation resistor (90) is connected across the outputs of the power division networks. In operation, an input signal is split between the two power division networks (70, 80) with equal voltage and phase. The power split between the two outputs is adjusted by adjusting the open stub length, thereby varying the characteristic impedance level between the two power division networks. Any signal reflected back into any one of the power divider networks is absorbed by the isolation resistor. The stub length can be trimmed after device fabrication using a laser or abrasion system.

Abstract: A phase shifting circuit (10) which is especially suitable for use as a 180.degree. phase bit for an antenna element in a phased radar antenna array includes a first transmission line (16) connected between first and second diodes (22,24), which are connected to input and output terminals (12,14) respectively. Second and third transmission lines (18,20) are connected in series with each other between the input and output terminals (12,14). A third diode (26) is connected between the junction (28) of the second and third transmission lines (18,20) and ground. The first transmission line (16) is less than one-quarter wavelength long at the operating frequency of the circuit (10), whereas the second and third transmission lines (18,20) are each approximately three-eighths wavelength long. Forward biasing the diodes (22,24,26) causes substantially all of the signal to propagate from the input terminal (12) to the output terminal (14) through the first transmission line (16), producing minimum phase shift.