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A novel design of a 4 × 4 miniaturized UWB-MIMO (multiple-input, multiple-output) antenna with isolation improvement is proposed in this paper. The designing procedure of a flowershaped MIMO antenna is done using characteristic mode analysis (CMA). The flower-shaped UWB-MIMO antenna is made up of four symmetrical flower-shaped radiating elements that are isolated using an orthogonal method. The flower antenna's dimensions are 40×40×1.6 mm 3 (0.44λ 0 ×0.44λ 0 ×0.017λ 0 ). A flower-shaped radiator is used to get good the isolation in MIMO elements. Further isolation is enhanced by inserting a swastik-shaped stub on the ground to get return losses of S 11 < −10 dB and isolation of S 12 < −18 dB. The designed antenna covers the entire UWB (3.1 GHz-14 GHz) spectrum for impedance matching, including (10.7 GHz to 11.7 GHz), 11 GHz (10.7 GHz to 11.7 GHz), and 13 GHz (10.7 GHz to 11.7 GHz) (12.75 to 13.25 GHz). Good diversity performance is achieved in the UWB and ITU range. The designed antenna has a gain of 5.5 dB, an efficiency of 89%, an impedance bandwidth of 123.61%, an envelope correlation coefficient of 0.012, a diversity gain of nearer to 10 dB, a capacity channel loss of 0.29 bp/s/Hz, and a mean effective gain of less than −3.1 dB. The designed antenna is fabricated and tested. These simulated results are validated in state-of-the-art laboratories. According to the simulation and measurement results, this antenna is well suited for reliable wireless communication systems. The potentiality of the designed antenna is high, and the antenna is compact and portable.

Power spectrum is the considerable aspect in the atmospheric radar data processing to estimate wind parameters. Due to the poor resolution and high sidelobe level problems of the existing algorithms, there is a requisite for the novel data-dependent approaches. A non-parametric and hyperparameter-free iterative adaptive approach (IAA) is presented for the power spectral density estimation. This approach is able to work with single snapshot and is obtained by minimizing the weighted least square fitting criterion. The IAA method provides the accurate amplitude and frequency estimation for the simulated data. The data for the above study is collected from Indian MST (mesosphere, stratosphere, and troposphere) radar. The power spectrum and Doppler frequency are estimated using IAA. In this paper, zonal (U), meridional (V), windspeed (W) are also calculated and validated using Global Positioning System Sonde data. The effectiveness of the spectral estimation performance showed by IAA is demonstrated and assessed.

In this article, very compact 2 × 2 and 4 × 4 MIMO (Multiple-Input and Multiple output) antennas are designed with the help of Characteristics Mode Analysis to enhance isolation between the elements for UWB applications. The proposed antennas are designed with Characteristic Mode Analysis (CMA) to gain physical insight and also to analyze the dominant mode. To improve isolation and minimize the mutual coupling between radiating elements, elliptical shaped stubs are used. The dimensions of the 2 × 2 and 4 × 4 MIMO antennas are 0.29λ0 × 0.21λ0 (28 × 20 mm2) and 0.29λ0 × 0.42λ0 (28 × 40 mm2), respectively. These antennas cover the (3.1 GHz–13.75 GHz) UWB frequency band and maintain remarkable isolation of more than 25 dB for both 2 × 2 and 4 × 4 antennas. The impedance bandwidth of the proposed 4 × 4 MIMO antenna is 126.40% from 3.1 GHz to 13.75 GHz, including X-Band and ITU bands. The proposed 4 × 4 antenna has good radiation efficiency, with a value of more than 92.5%. The envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), and channel capacity loss (CCL) matrices of the 4 × 4 antenna are simulated and tested. The corresponding values are 0.0045, 9.982, −3.1 dB, and 0.39, respectively. The simulated results are validated with measured results and favorable agreements for both the 2 × 2 and 4 × 4 UWB-MIMO antennas.