RAJASEKHAR MANDA
@pace.ac.in
Associate Professor, Electronics and Communication Engineering
PACE Institute of Technology and Sciences (A)
RESEARCH INTERESTS
Antennas, Radar Signal Processing
Scopus Publications
Scopus Publications
Tathababu Addepalli, Jagadeesh Babu Kamili, Subbarao Boddu, Rajasekhar Manda, Anveshkumar Nella, and Bandi Kiran Kumar
Springer Science and Business Media LLC
Tathababu Addepalli, Rajasekhar Manda, Thota Vidyavathi, Kamili Jagadeesh Babu, and Bandi Kiran Kumar
Wiley
The design of novel compact two‐element and eight‐element lotus shaped multiple‐input‐multiple‐output (MIMO) antenna system employing pattern diversity with enhanced isolation characteristics is presented. The proposed two‐element antenna system is arranged rotationally on a square‐hollow substrate resulting in an eight‐element MIMO antenna system employing pattern diversity. The developed eight‐element MIMO antenna system resonates in the frequency range 3.1 to 14.6 GHz housing the complete UWB band with triple band‐notch characteristics at 3.7–4.5 GHz (C‐band satellite down link [3.7–4.2 GHz]), 5.1–5.9 GHz (WLAN) and 6.8–8.25 GHz (X‐band satellite down link (7.25–7.75 GHz) and up link (7.9–8.4 GHz)) bands. The antenna system gives element‐to‐element isolation of more than 25 dB in the majority of the operating band with a peak gain of 6.8 dBi and a maximum 90% efficiency. The important MIMO metrics like ECC (envelope correlation coefficient), DG (diversity gain), total active reflection coefficient (TARC), channel capacity losses (CCL) and MEG (mean effective gain) are presented for both two‐element and eight‐element to estimate the performance the proposed antennas in multi‐antenna environments. The both two‐ and eight‐element designs are fabricated and the measured results of those are well agreed with simulation results.
Tathababu Addepalli, K. Vasu Babu, T. Vidyavathi, Rajasekhar Manda, and Bandi Kiran Kumar
Springer Science and Business Media LLC
Udayabhaskar Pattapu, Rajasekhar Manda, and Sushrut Das
Informa UK Limited
Manish Sharma, Tathababu Addepalli, Rajasekhar Manda, T. Vidyavathi, and Prabhakara Rao Kapula
Cambridge University Press (CUP)
Abstract This research investigates the MIMO antenna by using the Theory of Characteristics Mode (TCM) where 10 modes are subjected in designing. Also, 5 modes are the significant mode and 2 modes correspond to non-significant which defines the operating bandwidth and notched bands. The proposed 2 × 2 MIMO antenna configuration is designed for wideband applications with a size of 0.44 × 0.68 mm2. The two isolated 12-sided polygons radiating patches placed adjacent to each other share a common ground which is printed on an FR4 substrate. The measured impedance bandwidth covers bandwidth 3.11–11.98 GHz with two bands rejecting capability: Wireless Local Area Network (WLAN) and Downlink-Uplink Satellite (DUS) system. These two interfering bands are mitigated by etching a C-type slot on the radiating patch and an inverted U-type slot in the microstrip feed. The simulated and measured results are also compared in the far-field region (Normalized Radiation Efficiency (NRE), Peak Gain (PG), and 2-D/3-D radiation pattern). Proposed MIMO antenna also offers good diversity performance with ECC2×2 < 0.00001, DG2×2 > 9.999 dB, TARC2×2 < −15.0 dB, CCL2×2 < 0.001 b/s/Hz and MEG2×2 ≅ −3.0 dB.
Tathababu Addepalli, Jagadeesh Babu Kamili, D. Vishnu Vardhan, Kiran Kumar Bandi, Rajasekhar Manda, Bhaskara Rao Perli, and V. Satyanarayana
Informa UK Limited
Tathababu Addepalli, Jagadeesh Babu Kamili, Kiran Kumar Bandi, and Rajasekhar Manda
IEEE
A Novel Multiple Input Multiple Output Antenna (MIMO) with eight-element antennas is proposed. The MIMO system covers the frequency range 3.3 GHz to 6 GHz, making the antenna suitable for 5G sub: 6 GHz applications. The 5G bands covered by the antenna are N77 (3.3 to 4.2 GHz), N78 (3.3 to 3.8 GHz), N79 (4.4 to 5.0 GHz), and WLAN (5.15 to 5.85 GHz). The developed antenna works in these bands with a reduced mutual coupling of -15 dB between the adjacent elements of the MIMO system. The maximum isolation of 60 dB is obtained among the diagonal elements with a gain of 6 dBi and radiation efficiency of 97%. The proposed antenna is very compact with a low profile with dimensions of $\\mathbf{72}\\ \\mathbf{mm} \\times \\mathbf{72}\\ \\mathbf{mm} \\times \\mathbf{1.6}\\ \\mathbf{mm}$ and eight antenna elements. The important MIMO parameters like CCL (Channel Capacity Loss), TARC (Total Active Reflection Coefficient), and ECC (Envelope Correlation Coefficient) are also presented to validate the performance of the proposed eight-element antenna system under the MIMO environment.
Tathababu Addepalli and Rajasekhar Manda
IEEE
This work proposes a novel design of a 4-element MIMO antenna for 5G sub: 6GHz N77/N78 and N79 band applications. The proposed work is designed on a 100 × 100 mm2size FR4 defected substrate having a height of 1.6mm, constant of 4.4. Initially, a 30 × 30 mm2size single antenna is designed; later, it is extended to a 4-element antenna. Both the antennas work in the range of 3.0GHz to 5GHz and cover the 5G sub:6 GHz bands, which include N77 (3.3-4.2 GHz) and N78 (3.3-3.8 GHz) and N79 (4.4-5.0 GHz). The isolation values above 17.5 dB when elements are placed orthogonal and above 25 dB are attained in the structure's entire working region. High radiation efficiency and gain values are attained due to the systematic design. The proposed antenna is fabricated and checked with the measured results with simulation results. The compared results are almost in good agreement, and these results include S-parameters and diversity performance characteristics. The proposed antenna is designed with a popular and efficient simulator known as Ansoft HFSS.
Tathababu Addepalli and Rajasekhar Manda
IEEE
This paper designs an 8-element MIMO antenna with the connected ground on a novel swastika-shaped substrate for super-wideband applications. The proposed design is working in the band of 2.9–15.3 GHz with element-to-element isolation is minimum of above 15 dB, and the overall structure dimensions are $88\\times 88\\times 1.6\\ mm^{3}$. The proposed structure is designed on low cost FR4 material with a constant of 4.4, and it covers the entire band of Ultra Wide Band (UWB), X-band, and partial Ku band region. The radiation performance of the design is evaluated with efficiency and gain results. The gain values of 7.2 dBi occur at 6.8 GHz, and a minimum of above 3 dBi is achieved in the entire working region. The proposed design's efficiency values above 75% are attained in the complete working region. The diversity characteristics Total Active Reflection Coefficient (TARC) and Channel Capacity Losses (CCL) are calculated using S-parameter results and are presented.
Kadiyala Yaswanth, Rajasekhar Manda, and Durgesh Nandan
Springer Singapore
Guthula Hema Mutya Sri, Galla Bharggav, Rajasekhar Manda, and Durgesh Nandan
Springer Singapore
Rajasekhar Manda, P. Preetham Raj, and P. Rajesh Kumar
IEEE
Most of the RADAR and Telecommunication system are affected by EMI. In the past, frequency allocation to different frequency bands can minimize the EMI and narrow bandwidth usage. EMI reduction requires other means than frequency allocation possibly non-interfering coded waveforms or sequences such as PI, P2, P3, P4, Px, Golomb, Frank, and the Chu known as Polyphase sequences. The commonly used waveforms in RADAR are frequency phase and amplitude. In this paper, the Modified Merit Factor (MMF) and minimum correlation level are used as the parameters to analyze the EMI reduction in RADAR. Weighted Integrated sidelobe level (WISL) metric can reduce the correlation level for a region of interest. Out of Cyclic Algorithm pruned obtained Polyphase sequences CAP (Chu), CAP (Px) and CAP (Golomb) exhibit the minimum correlation level as -81.77dB, 132. 77dB and 155. 15dB for Lengths $10^{2}, 10^{3}$ and $10^{4}$ respectively. These sequences are more immune to interference. All the results are implemented on MATLAB.
Rajasekhar Manda and P. Rajesh Kumar
IEEE
Most of RADAR devices are capable of transmitting many different types of waveforms. Certain types of waveforms are better suited for detecting how fast an object is traveling, while others are better at detecting the range resolution of an object. Applications such as radar, sonar and medical imaging, demand proper designs of the probing waveform. A well-synthesized waveform can significantly increase the system performance in terms of signal-to-interference ratio, Merit factor, ISL (integrated side lobe level), PSLR (peak side lobe ratio), spectrum containment, beam pattern matching, target parameter estimation and so on. The focus of this work is on designing probing waveform i.e Unimodular sequence using computational algorithms CA, CAN & WeCAN with AF (Ambiguity Function) plots. These are best suited for designing probing sequence in COGNITIVE RADAR.