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A microwave Hilbert transformer is introduced as a new component for real-time analog processing (RAP). In contrast to its optical counterpart that resorts to optical fiber gratings, this Hilbert transformer is based on the combination of a branch-line coupler and a loop resonator. The transfer function of the transformer is derived using signal flow graphs, and two figures of merits are introduced to effectively characterize the device: the rotated phase and the transition bandwidth. Moreover, a detailed physical explanation of its physical operation is given, using both a steady-state regime perspective and a transient regime perspective. The microwave RAP Hilbert transformer is demonstrated experimentally and demonstrated in three applications: edge detection, peak suppression, and single-sideband modulation. [ABSTRACT FROM AUTHOR]

We model, demonstrate, and characterize dispersion code multiple access (DCMA), and hence, show the applicability of this purely analog and real-time multiple access scheme to high-speed wireless communications. We first mathematically describe DCMA and show the appropriateness of Chebyshev dispersion coding in this technology. We next provide an experimental proof-of-concept in a $2\times 2$ DCMA system. Finally, we statistically characterize DCMA in terms of bandwidth, dispersive group delay swing, system dimension, and signal-to-noise ratio. [ABSTRACT FROM PUBLISHER]

We present a loss-gain equalized reconfigurable C-section analog signal processor (ASP) for dynamic radio analog signal processing (R-ASP). Such an ASP provides realtime tunable group delay response with all-pass transmission. We propose a lumped loss-gain implementation, where tuning and equalization are mostly easily achieved. A theoretical study derives the transfer function and the fundamental characteristics of the device. The ASP is finally experimentally demonstrated, first using a single loss-gain pair and finally a three cascaded loss-gain pair structure with full reconfigurability, where up-chirp and down-chirp group delays are shown for illustration. It is expected that this ASP will find wide applications in R-ASP systems requiring dynamic adaptability. [ABSTRACT FROM AUTHOR]

A novel time-reversal subwavelength transmission technique, based on pulse-shaping circuits (PSCs), is proposed. This technique removes the need for complex or electrically large electromagnetic structures by generating channel diversity via pulse shaping instead of angular spectrum transformation. It is shown that, compared to our previous time-reversal system based on chirped delay lines, the PSC approach offers greater flexibility and larger possible numbers of channels, i.e., ultimately higher transmission throughput. The superiority of the PSC time-reversal system is also demonstrated experimentally. [ABSTRACT FROM PUBLISHER]

Generalized coupled-line all-pass phasers, based on cascaded C-sections (CCSs), cascaded coupled-lines (CCLs), and hybrid-cascaded (HC) coupled transmission-line sections, are presented and demonstrated using analytical, full-wave, and experimental results. It is shown that for N commensurate coupled-line sections, CCL and HC phasers exhibit N group-delay peaks per coupled-line section harmonic frequency band, in contrast to the CCS configuration, which exhibits only one peak within this band. It is also shown that for a given maximum achievable coupling-coefficient, the HC configuration provides the largest group-delay swing. A wave-interference analysis is finally applied to the various coupled-line phasers, explaining their unique group-delay characteristics based on physical wave-propagation mechanisms. [ABSTRACT FROM PUBLISHER]