dB Power Loss Research Articles

Low-Complexity Beamforming Optimization for IRS-Aided MU-MIMO Wireless Systems

In this paper, we propose a cost-efficient beamforming optimization algorithm for multi-user wireless communication systems associated with the intelligent reflecting surface (IRS). From the baseline successive refinement algorithm, which gives a sub-optimal solution for the power minimization problem under the signal-to-interference-plus-noise-ratio (SINR) constraint at each user, several optimization techniques are proposed to reduce the computation complexity while maintaining the algorithm-level performance. To reduce the number of required multiply-accumulate (MAC) operations, we first simplify the complicated matrix inversion by utilizing the channel hardening effect. We also present the two-phase refinement process for the group-level optimization of phase-shift elements, further relaxing the computation complexity as well as the processing latency. Applying the proposed optimization techniques, as a result, numerical results show that the fully-optimized algorithm can reduce the computational costs by up to 89.4% while showing less than 1 dB power loss, leading to the practical solution for the next-generation IRS-aided communication.

A 38–40 dB Power Gain and 2.4 dB NF Three-Stage Cascaded/Cascoded LNA for Long Range Automotive Radar Application

This paper demonstrates novel technique to devise a three-stage millimeter-wave low noise amplifier (LNA) operated at 76–77 GHz frequency band used in long range automotive Radar application. LNA having high power gain along with low noise figure is necessary for long range automotive Radar application. High power gain is one of the biggest challenges in the LNA design of the long range automotive application (nearly 40 dB power loss of received echo signal). Here, we propose a novel method to design an LNA using three configurations, i.e., cascaded, cascoded and differential. Design methodology used for this proposed LNA are also discussed in this paper. Power, small-signal, noise and stability analysis of post-layout and RC-extracted novel LNA are carried for the same. The proposed LNA is implemented in 45 nm complementary metal oxide semiconductor process, and its results show 2.4 dB noise factor 38–40 dB maximum power gain. It also provides outstanding stability and minimum size which is best suitable for Automotive integrated Radar sensor.

The Landau damping of magnetospherically reflected whistlers within the plasmasphere

Evidence for significant energetic electron precipitation by magnetospherically reflected (MR) whistlers has recently been found in SAMPEX energetic electron data [Blake et al., 2001], implying that these waves undergo many reflections before being attenuated through Landau damping. We quantify the Landau damping of MR whistlers, using recent energetic electron data from the HYDRA instrument on POLAR and show that the MR wave components can endure for as long as ∼20 seconds and undergo as many as 17 reflections before experiencing a 6 dB power loss due to Landau damping. Our results suggest that MR whistler wave energy may thus significantly enhance the total amount of energetic electron precipitation induced by each individual lightning discharge.

On the Feasibility of Power Transmission using Microwave Energy in Circular Waveguide*

SummaryA cylindrical waveguide operating in the TE01 mode can transmit powers of the order of thousands of megawatts in frequency ranges below lOgc/s with acceptable copper losses over distances of hundreds of miles, provided It can be made with sufficient accuracy to avoid excessive power transfer into other unwanted high-loss modes. The tolerances on the guide straightness appear to be the most severe limitation on the use of this type of guide as a high power system component. These tolerances are evaluated here and found to be of the order of 10 to 100 mils in distances of a few hundred feet for typical values of the other parameters such as 2.0 gc/s in a 1-meter-radius guide providing one db power loss in a distance of 200 miles. It is also shown that low loss bends (about 0.005 db/mile) with bending radii of the order of 1.0 mils are possible if the length of the bend is accurately controlled and the guide has a dielectric lining of the proper thickness.

Cylindrical waveguide as a power transmission medium—Limitations due to mode conversion

A cylindrical waveguide operating in the TE 01 mode can transmit powers of the order of thousands of megawatts in frequency ranges below 10 Gc/s with acceptable copper losses over distances of hundreds of miles, provided it can be made with sufficient accuracy to avoid excessive power transfer into other unwanted high-loss modes. The tolerances on the guide straightness appear to be the most severe limitation on the use of this type of guide as a high power system component. These tolerances are evaluated here and found to be of the order of 10 to 100 mils in distances of a few hundred feet for typical values of the other parameters such as 1.0 Gc/s in a 2-meter-diameter guide providing 1 dB power loss in a distance of 200 miles. Tolerances on diameter variations and cross-section ellipticity are also evaluated and found to be of the same order of magnitude as the deviations from straightness, but should be easier to control by the proper manufacturing process. It is also shown that low loss bends (about 0.01 dB/mile) with bending radii of the order of 0.5 mile are possible if the length of the bend is accurately controlled and the guide has a dielectric lining of the proper thickness.