Compact tunable bandstop filters using defected microstrip structure for multi-standard wireless systems

A novel compact tunable bandstop filter using Defected Microstrip Structure (DMS) is presented in this paper. The structure utilizes a modified T shaped DMS which helps in miniaturization of the filter. To verify the concept, one such filter was simulated, designed, fabricated and tested. Measurements on a fabricated tunable filter confirm the accuracy of the design procedure. The tuning range of 20% is achieved, ranging from 2.26 GHz to 2.747 GHz. Tuning is achieved by using NXP BB179 varactor diode. A nonlinear distortion evaluation in a tunable filter was experimentally verified. Experimental verification shows the filter is highly linear.

On the structure and performance of a novel blind source separation based carrier phase synchronization error compensator

In this paper we carry out a detailed performance analysis of a novel blind-source-seperation (BSS) based DSP algorithm that tackles the carrier phase synchronization error problem. The results indicate that the mismatch can be effectively compensated during the normal operation as well as in the rapidly changing environments. Since the compensation is carried out before any modulation specific processing, the proposed method works with all standard modulation formats and lends itself to efficient real-time custom integrated hardware or software implementations.

Variable centre frequency resonator based bandpass Σ-Δ modulator

A novel resonator-based bandpass Σ-Δ modulator with an in-built variable centre frequency feature is presented. This structure is designed by analytically determining and subsequently verifying through behavioural level simulations the necessary compensation hardware to be placed in the feedback to ensure stability and good dynamic range performance.

Rethinking crises and the accretion of executive power: the “War on Terror” and conditionality evidence from seven political systems

External shocks to democratic systems are likely to threaten the stability of relations between the executive and the representative assembly. This article investigates the impact of the so-called “war on terror” on executive-assembly relations in comparative perspective. We analyze data from seven countries, which varied in terms of form of government, level of democracy, culture, social structure, and geographic location, to evaluate its effects. We find that whereas in some systems the “war on terror” altered the balance of power between the executive and the assembly, in other cases the extant balance of power was preserved. We postulate various conditions under which the constitutionally sanctioned balance of power is most likely to be preserved in times of crisis.