Design and Analysis of 0.5–2.0 GHz RF Frontend Subsystems for IEMI Applications

Abstract

We present RF frontend subsystems for detecting intentional electromagnetic interference (IEMI) over 0.5–2 GHz. The frontend includes a printed log periodic antenna and integrated attenuator cum fourth-order bandpass filter. First, the proposed antenna incorporates trapezoidal shape reflectors with L-shape load, spilt ring resonators, rectangular strips with trapezoid-shaped variation, and periodic strips. The antenna occupies a volume of 320 × 250 × 1.6 $\rm mm^{3}$. A good impedance matching and the minimum gain variation of 0.72 dBi with an average gain of 4.5 dBi are demonstrated in measurements for the fabricated prototype. Second, a cascade of a 5 dB attenuator and a second-order bandpass filter (BPF) are integrated on both sides of an FR4 epoxy multilayer substrate, thereby realizing an integrated 10 dB attenuator cum fourth-order filter prototype. The second-order BPF is designed with short-circuited stubs and miniaturized with stepped-impedance resonators and meander lines. The attenuator is implemented with passive $\pi$-network. The attenuator-cum-filter prototype occupies 40 × 35 × 1.6 $\rm mm^{3}$. On measurement, the fabricated prototype shows desired impedance matching and attenuation of 12–13.6 dB over 0.5–1.7 GHz and 13.6–16.16 dB over 1.7–2 GHz. It has a wide stopband with $|S_{21}| < -40$ dB over 2.4–4 GHz. Further, we demonstrate the reception of voltage scaled IEMI signals using the proposed RF frontend subsystems.