Superconducting Quantum Interference Devices for the Detection of Magnetic Flux and Application to Airborne High Frequency Direction Finding

Electrically small antennas trade reception performance for physical size reduction. The SQUID maximizes the reception performance; still achieving a physically small size leading to satisfying the demanding antenna requirements of an airborne high frequency direction finding antenna system. High frequency electromagnetic reception for a direct current (DC) superconducting quantum interference device (SQUID) is simulated using the resistor-capacitor-shunted-junction (RCSJ) electronic circuit model, producing a set of two-dimensional ordinary differential equations to describe the electrical operating characteristics for the DC SQUID. A time-varying magnetic flux, consisting of frequencies from the HF band, is applied to characterize the voltage response of the DC SQUID. An instantaneous voltage develops across the DC SQUID, although a fast time-average must be computed to produce usable voltage samples. These voltage samples are shown to be representative samples of the applied time-varying signal containing a voltage bias. The waveform produced from these voltage samples is periodic, while preserving the phase of the incident signal. The HF reception characteristics of a single DC SQUID is shown, including an examination for expanding the loop area, simulating a DC SQUID array. Additionally, the DC SQUID is compared to the MGL-S8A BDOT sensor using by optical responsitivity