Jonathan Wilkerson

• Sandia National Laboratories

An analytic formulation of passive intermodulation distortion (PIM) in antennas is presented for PIM introduced by electro-thermal modulation of conductivity by current-related losses. A silver rectangular patch antenna was fabricated using a sapphire substrate isolating the thermal process from other possible sources. Two-tone testing at 990 MHz u...

Passive intermodulation distortion (PIM) generated on antennas is experimentally investigated and shown to agree with calculations based on an electro-thermal origin. Two-tone testing is used in the investigations with tone spacings ranging from 3 Hz to 100 kHz. The two-tone measurement system has a minimum spurious-free dynamic range of 125 dB at...

The essence of radar, radio and wireless sensor engineering is extracting small information-bearing signals. This is notoriously difficult and engineers compensate by transmitting high power signals, reducing range, and spacing wireless systems in frequency and time. New understandings of passive intermodulation distortion, thermal effects, time-fr...

A theoretical treatment of distributed electro-thermally induced intermodulation distortion is developed for microstrip transmission lines. The growth of passive intermodulation distortion (PIM) along the length of a line is derived accounting for both loss and electrical dispersion. PIM dependencies on width, length, thickness, and substrate param...

This paper presents an intermodulation distortion measurement system based on automated feedforward cancellation that achieves 113 dB of broadband spurious-free dynamic range for discrete tone separations down to 100 Hz. For 1-Hz tone separation, the dynamic range is 106 dB, limited by carrier phase noise. A single-tone cancellation formula is deve...

An analytic formulation of dynamic electro-thermally induced nonlinearity is developed for a general resistive element, yielding a self-heating circuit model based on a fractional derivative. The model explains the 10 dB/decade slope of the intermodulation products observed in two-tone testing. Two-tone testing at 400 MHz of attenuators, microwave...

The use of sound as a means to gather information about our environment has been developed with limited scope over the past several decades. The primary application of this technology has been ultrasound and ultrasonic ranging. Recent developments in nonlinear acoustics have proven that two-tone measurements and directional high frequency parametri...

This paper presents an intermodulation distortion measurement system based on automated feedfoward cancellation that achieves 95 dB of broadband dynamic range. A single tone cancellation formula is developed requiring only the power of the probing signal and the power of the combined probe and cancellation signal to predict the required phase shift...

Co-site interference has been a vexing problem in communications since the origins of radio. The problem occurs when a radio operating at one frequency is jammed by a radio or set of radios operating at other frequencies or time slots. It is well understood that nonlinear mixing can result in the generation of spurious interfering signals but this...

This paper explores the generation of passive intermodulation distortion products through the self heating of resistive elements in a microwave attenuator. A compact electrothermal resistor model requiring only two physical parameters is developed for platinum resistors and applied to a resistive attenuator pi network to predict electrothermal PIM....