Reflection-Type Artificial Dielectric Substrate Microstrip Dispersive Delay Line (DDL) for Analog Signal Processing

A reflection-type artificial dielectric substrate (ADS) microstrip dispersive delay line (DDL) for analog signal processing is presented. This DDL is realized by nonuniformly alternating conventional and ADS microstrip sections with a linearly increasing period (linear group delay or constant chirp) so that the different spectral components of a modulated signal incur different delays proportional to their frequency to be discriminated in time. Design guidelines are provided. The proposed DDL is demonstrated theoretically, numerically, and experimentally, and is fully characterized in terms of reflective level, bandwidth, group delay, and chirping coefficient for excitation at both ports. The DDL is then demonstrated in a frequency discriminator. Finally, it is compared with a stepped-impedance DDL and a sinusoidal-impedance DDL, and shown to exhibit superior symmetry along to smaller overall loss due to dramatically mitigated radiation, thereby leading to superior performances in various analog signal-processing systems such as impulse delay lines, real-time Fourier transformers, and compressive receivers.