Receiver protecting device based on microstrip structure with high-temperature superconductor film

Abstract

New design of an effective device for protection against high power electromagnetic pulses has been created based on a pair of noninteracting microstrip resonators, which are coupled in the working fre quency band via a third resonator based on a thin film of high temperature superconductor (HTSC) occur ring in the superconducting state. Under the action of an electromagnetic pulse with the power above a cer tain threshold, the HTSC film element passes from the superconducting to normal (high resistivity) state, thus breaking the coupling between resonators. This leads to power limitation at the device output due to a strong signal reflection from the input.

Reflective Power Limiter for X-Band With HTSC Switching Element

“…The frequency-dependence of these coefficients originates from individual distribution of voltage and current (as well as magnetic and electric fields) along the resonator's strip at every frequency. Earlier [19], it was shown that, by choosing a resonator shape and a gap between resonators, one can achieve equality between inductive k L and capacitive k C coupling coefficients at some frequency, which means zeroing of total coupling coefficient. When this occurs, a damping pole (a sharp minimum of transmission) results at this frequency.…”

“…Previously, [19] has shown that the leakage level in the device depends on the width of the bridge (narrow part) in the HTSC dumbbell-shaped element and it is of the order of tens mW. It is obvious that the critical power (i.e.…”

“…Previously, we [19] proposed a PL, based on the 3pole microstrip bandpass filter (BPF), where only the central part of the internal resonator was made from HTSC thin film and the remaining parts from copper. When the superconducting part of the resonator is in the low-loss state, all the resonators form a pass-band, while in the high-loss state there is no coupling between the external resonators and the internal one, and hence most part of the incoming signal power reflects back.…”

Compact Microwave Power Limiter with HTSC Element

“…Increase in distance S 2 leads to reduction of interaction between outer resonators with each other through inner one, and, as a result, bandwidth decreases. As researches showed earlier [5] for such limiters reduction of bandwidth leads to increasing attenuation of a signal in the limitation mode. That is a positive factor for power limiter.…”

“…This shortcoming is absent in HTSC power limiters designed on the basis of the new concept [5,6], where limitation occurs due to reflection, not absorption. Such device has a structure of a three-resonator bandpass microstrip filter.…”