Design and fabrication of a microstrip feedline-based Vivaldi antenna in the frequency range of 6.0–8.0 GHz have been presented. The Vivaldi antenna is a planar antenna, fabricated at the microstrip feedline by having an exponentially tapered slot profile on it. An optimized computer-aided design has been developed and simulated for the desired radiation parameters like voltage standing wave ratio, bandwidth, directionality, beam-width, etc. The optimized design has been fabricated and tested. Wherever the results are not found as desired; problem has been comprehensively investigated and analyzed. This is found associated with a discontinuity at feed line, fabrication tolerance constraints and parasitic capacitance at the edges or the bent of the microstrip feedline which introduce the parasitic reactance in antenna design. Here, the presented work explores a generalized theoretical procedure for the compensation of associated problem by incorporating the reactive patch on the feedline. The developed theory is applied in fabrication and tested for the desired results.

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Stimulated Brillouin scattering has been widely utilized to realize frequency-agile narrowband and wideband microwave photonic bandpass filters by primarily utilizing its gain response. However, most demonstrated wideband Brillouin-based filters are limited in operation due to the high-power requirements for bandwidth tailoring. We propose a novel approach to realize wideband reconfigurable, Brillouin-based microwave photonic bandpass filters employing RF interferometry and advanced phase engineering. Demonstrated filters exhibit >20 dB selectivity and >700 MHz bandwidth using only 8 dB peak SBS gain (of intrinsic linewidth 30 MHz), and total optical pump power of only ∼14 dBm. We also demonstrate frequency tunability up to 22 GHz. The filter passband has a very flat and highly linear phase response, thus exhibiting zero group delay which we have experimentally verified by propagating an RF pulse at 10.25 GHz. Furthermore, the filter does not suffer from added Brillouin noise in the passband, which is a major advance compared to conventional Brillouin-based microwave photonic sub-systems. This paper presents simulations, mathematical analysis, and experimental results of the proposed filter. The proposed filter demonstrates a pathway toward power-efficient Brillouin-based microwave photonic filters, utilizing SBS responses, in combination with phase manipulation for advanced filtering operations.

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