Mithilesh Kumar

Bio: Mithilesh Kumar is an academic researcher from Rajasthan Technical University. The author has contributed to research in topics: Microstrip antenna & Patch antenna. The author has an hindex of 12, co-authored 103 publications receiving 734 citations. Previous affiliations of Mithilesh Kumar include Indian Institute of Technology Delhi & University College Hospital.

Miniaturized Slotted Ground UWB Antenna Loaded with Metamaterial for WLAN and WiMAX Applications

Abstract: This paper presents a miniaturized ultra wideband (UWB) antenna with metamaterial for WLAN and WiMax applications. For miniaturization of UWB antenna resonating 3.1–10.6 is designed Ghz using fractalization of the radiating edge and slotted ground structure approach. A miniaturization of active patch area and antenna volume is achieved up to 63.48% and 42.24% respectively, with respect to the conventional monopole UWB antenna. This antenna achieves a 143% impedance bandwidth covering the frequency band from 2.54GHz to 15.36GHz under simulation and 132% (2.95–14.28 GHz) in measurement. The electrical dimension of this antenna is 0.32λ × 0.32λ (38mm×38mm) at lower frequency of 2.54GHz. As per IEEE 802.11a/b/g and IEEE 802.16e standards, WLAN (2.4–2.5 GHz, 5.150–5.250 GHz, 5.725–5.825 GHz), WiMAX (3.3–3.8 GHz) bands are achieved by using slotted ground structure and metamaterial rectangular split ring resonator. The proposed antenna is fabricated on FR4 substrate of thickness 1.6mm and a dielectric constant 4.3 and tested. The proposed antenna yields a −10 dB impedance bandwidth of about 11.1% (2.39–2.67 GHz), 59.1% (2.87–5.28 GHz) and 7.4% (5.58–6.01 GHz) under simulation and 4.5% (2.41–2.52 GHz), 51.1% (3.12–5.26 GHz) and 3.8% (5.69– 5.91GHz) in measurement for 2.4, 3.5 & 5 and 5.8GHz bands respectively. Stable radiation patterns with low cross polarization, high average antenna gain of 3.02 dBi under simulation and 2.14 dBi in measurement and measured peak average radiation efficiency of 76.6% are observed for the operating bands. Experimental results seem in good agreement with the simulated ones of the proposed antenna.

A Frequency Band Reconfigurable UWB Antenna for High Gain Applications

Abstract: An octagonal shape patch antenna with switchable inverted L-shaped slotted ground is designed for frequency band reconfigurable and experimentally validated. The antenna is capable of frequency band switching at five different states including an ultra wideband (UWB) state, two narrowband states and a dual-band state by using RF switching element p-i-n diodes. In the case of ultrawide band (UWB) state, the proposed antenna operates over impedance bandwidth of 141% (2.87- 16.56 GHz) under simulation and 139% (2.85-15.85 GHz) in measurement with return loss S11 < �10 dB. For two narrowband states, 10 dB impedance bandwidth achieved is 16% (5.05-5.91 GHz) and 11% (8.76-9.80 GHz) under simulation and 14% (5.01-5.79 GHz) and 10% (8.68-9.69 GHz) in measurement, respectively. For the dual band state, 10 dB impedance bandwidth of 2.21-2.52 GHz (13%) & 5.07- 5.89 GHz (15%) and 2.18-2.52 GHz (14%) & 8.78-9.71 GHz (10%) under simulation and 2.20-2.50 GHz (12%) & 5.05-5.90 GHz (15%) and 2.19-2.50 GHz (13%) & 8.70-9.60 GHz (9%) in measurement with return loss S11 < �10 dB. The proposed antenna is capable to serve in different wireless communication applications such as WLAN (802.11b/g/n (2.4-2.48 GHz), 802.11a/h/j/n (5.2 GHz), ISM band (2.4- 2.5 GHz)), Bluetooth (2400-2484 MHz), WiMAX (2.3-2.4 & 5.15-5.85 GHz), WiFi (2.40-2.48, 5.15- 5.85 GHz) and UWB (3.1-10.6 GHz). It also works at 9.2 GHz where airborne radar applications are found. Next, the antenna gain is improved with the help of a circular loop frequency selective surface (FSS) and a PEC (perfect electric conductor) sheet. Measured peak gain represents average improvements about 4 dB-5 dB over the UWB band. Experimental results seem in good agreement with the simulated ones of the proposed antenna with and without the frequency selective surface.

Experimental Investigation of the Breast Phantom for Tumor Detection Using Ultra-Wide Band-MIMO Antenna Sensor (UMAS) Probe

Abstract: In this work, a novel Ultra-wideband-Multi-Input-Multi-Output Antenna Sensor (UMAS) probe is designed for the detection of the malignant cells in the breast. The Sensor probe has four radiating elements and it is operated within the 2.8 GHz to 20 GHz ultra-wide band range. Isolation between the radiating element is more than 20 dB. Further, three kinds of the breast phantoms (i.e. normal phantom, phantom with single and multiple tumors) are fabricated using tissue mimicking material. The electrical characteristics of the malignant cells are different from non-malignant cells of the breast. The S-parameter and Specific Absorption Rate (SAR) analysis are best approaches to detect the malignant cells in the breast. The UMAS sensing probe is embedded on the phantoms and S-parameters of the probe are recorded from the Vector Network Analyzer (VNA). Measured S-parameters of the probe for normal and malignant phantoms are differ from each other. The statistical machine learning concept of Principal Component Analysis (PCA) is also applied on the measured S-Parameters. Which exhibits clear detection of normal and malignant breast phantoms. Further verification is done by using Simulation based specific absorption rate (SAR) study of the phantom models for tumor detection. The obtained maximum SAR results are well differentiating the normal phantom.

Microstrip patch antenna for radiolocation using DGS with improved gain and bandwidth

Abstract: This paper presents the analysis of compact triband microstrip patch antenna for radiolocation. The proposed structure shows the multi-frequency band operation and it covers C and X-band frequencies that are allocated for radiolocation application of radar. Firstly dual band frequency operation achieved by simple rectangular microstrip patch antenna with four rectangular slots and for getting triple band a cylindrical slot is cut on the patch. For improving the performance (gain, directivity & bandwidth) of microstrip patch antenna rectangular DGS (defective ground structure) is used. This antenna is designed on FR-4 substrate with dielectric constant 4.9 and thickness 1.8 mm and its size is 14 X 14 X 1.87 mm3. The parameters of proposed antenna like return loss, VSWR and radiation pattern (gain, directivity and efficiency) are simulated and analyzed using commercial computer simulation technology microwave studio (CST MWS). By simulating proposed antenna we get three frequency bands which are 5.84–6.03GHz, 9.00–9.32GHz and 10.43–10.73GHz with resonant frequencies 5.9, 9.1 and 10.4GHz. The gain of proposed antenna is improved by using the DGS structure as the gain without DGS at resonant frequencies was 2.3, 5.8 and 4.6dBi and after DGS it was enhanced to 2.5, 6.1 and 5.3dBi. And the requirement for microstrip antenna VSWR ≤ 2 is full filled by all the resonant frequencies. The antenna structure is very simple, compact and occupies less space all these qualities make this antenna suitable for practical applications.

Response to FCC 98-208 notice of inquiry in the matter of revision of part 15 of the commission's rules regarding ultra-wideband transmission systems

Abstract: In general, Micropower Impulse Radar (MIR) depends on Ultra-Wideband (UWB) transmission systems. UWB technology can supply innovative new systems and products that have an obvious value for radar and communications uses. Important applications include bridge-deck inspection systems, ground penetrating radar, mine detection, and precise distance resolution for such things as liquid level measurement. Most of these UWB inspection and measurement methods have some unique qualities, which need to be pursued. Therefore, in considering changes to Part 15 the FCC needs to take into account the unique features of UWB technology. MIR is applicable to two general types of UWB systems: radar systems and communications systems. Currently LLNL and its licensees are focusing on radar or radar type systems. LLNL is evaluating MIR for specialized communication systems. MIR is a relatively low power technology. Therefore, MIR systems seem to have a low potential for causing harmful interference to other users of the spectrum since the transmitted signal is spread over a wide bandwidth, which results in a relatively low spectral power density.