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This paper presents a miniaturized Vivaldi antenna in order to meet the practical requirements of antenna array applications. Compared to the conventional Vivaldi antenna (CVA), the width of the modified Vivaldi antenna aperture is reduced 38.05% by adding regular slot edges (RSE), which will prevent the antenna array from generating the grating lobes. Additionally, the RSE has improved the radiative...
An improved low profile CP directional antenna with high gain is proposed, which combines the equiangular spiral antenna, ground and two discrete grid parasitic layers. Every rectangular element in the grid layer is expressed by its code height i(j.k) in 0.9∼1.1, so that the whole antenna can be achieved by optimizing all these parameters. Later, the optimized low profile CP directional antenna is...
We experimentally demonstrate the best known 16-ary 4-d modulation format at 24.8 Gb/s using coherent optical OFDM, achieving 0.58 dB OSNR gain over PDM-QPSK at a SER of 10-2. With 7% overhead optimal codes, a 0.38 dB gain is theoretically achievable.
A 231.5-Gb/s PDM-OFDM signal with 256-iterative-polar-modulation, outperforming 256-QAM by 1.2 dB in required OSNR after soft-FEC decoding, is generated, FEC-decoded, and transmitted over a record distance of 800 km with 11.15-b/s/Hz intrachannel spectral efficiency.
Optical OFDM's high PAPR values limit the systems nonlinear tolerance (NLT). A 2.6-dB improvement in NLT has been found by peak clipping. Towards higher bit rates above 50 Gb/s, we observe an additional NLT increase of 8 dB per 10x increase in signal bit rate.
This paper investigates the electrothermal stress- induced performance degradation of a cascode low-noise amplifier (LNA) built using InGaP/GaAs heterojunction bipolar transistors (HBTs). Changes in device characteristics due to the electrothermal stress were examined experimentally. At the moderate base-emitter voltage, the base current increases and current gain decreases after stress. The SPICE...
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