Rajan Mishra

Relation of Forest Structure and Soil Properties in Natural, Rehabilitated and Degraded Forest

Relation of Forest Structure and Soil Properties in Natural, Rehabilitated and Degraded Forest Plant community structure, species diversity and soil properties of natural, rehabilitated and degraded forests were studied in order to assess relationship of different forests structure and soil properties in upper Indo-Gangetic plain of Uttar Pradesh state of India. The composition of species, population bundance and importance value of the woody species were investigated in each forest; the representative soil samples from 30 cm depth of each forest were also analyzed for the soil properties. Dominant families at the natural forest are Moraceae (21.9%) and Rubiaceae (15.6%) while at the rehabilitated forest are Moraceae (53.8%) and Fabaceae (23%). In the degraded forest, the Moraceae and Fabaceae are dominant families occupy 33% each. These among forest community structure indicate that degraded forests are less complex ecosystems than natural forest stands.

A Triple Band

A triple band

Shape Slotted PIFA for 2.4 GHz and 5 GHz WLAN Applications

shape slotted planar inverted-F antenna (PIFA) is proposed for ISM band 2.4/5 GHz applications. The results have been compared between the antenna with slotted ground plane and the antenna with intact ground plane. Various improvements in the simulated results, such as large bandwidth, large gain, and higher radiation efficiency, have been achieved in the antenna with slotted ground as compared to non-slotted ground PIFA antenna. The size of the antenna is 100 × 40 × 1.6 mm3. FR4 epoxy is taken as substrate of the antenna. Three resonant frequencies are obtained at 2.4, 3.76, and 4.68 GHz. Respective bandwidths obtained at these frequencies are 81.5 MHz., 102 MHz., and 683 MHz. The results have been simulated on Ansoft HFSS 13.0. Proposed antenna applications include dual-band WLAN operation at 2.4 and 5 GHz.

Bandwidth enhancement of a microstrip patch antenna for ultra-wideband applications

The microstrip antennas are used where size, weight, cost, and performance are constraints. Microstrip antennas (MSA) are being used in many government and commercial applications among which it is mostly used in wireless communication. The proposed antenna is designed for Ultra-wideband (UWB), it is designed on FR4 substrate material with er = 4.3 and 0.0025 loss tangent. The shape and size of patch in microstrip patch antenna plays an important role in its performance. In the proposed antenna design the respective changes have been introduced which includes slotting the feedline,adding a curved slot in patch and change in patch shape itself to improve the bandwidth of the conventional antenna. The simulated results of proposed antenna shows impedance bandwidth (defined by 10 dB return loss) of 2-11.1GHz, VSWR<2 for entire bandwidth of antenna and peak gain is 5.2 dB. Thus the antenna covers the UWB range and it can also be used for bands such as 2.4/3.6/5 -GHz WLAN bands, 2.5/3.5/5.5GHz WiMAX bands and X band satellite communication at 7.25-8.395 GHz.The microstrip antennas are used where size, weight, cost, and performance are constraints. Microstrip antennas (MSA) are being used in many government and commercial applications among which it is mostly used in wireless communication. The proposed antenna is designed for Ultra-wideband (UWB), it is designed on FR4 substrate material with er = 4.3 and 0.0025 loss tangent. The shape and size of patch in microstrip patch antenna plays an important role in its performance. In the proposed antenna design the respective changes have been introduced which includes slotting the feedline,adding a curved slot in patch and change in patch shape itself to improve the bandwidth of the conventional antenna. The simulated results of proposed antenna shows impedance bandwidth (defined by 10 dB return loss) of 2-11.1GHz, VSWR<2 for entire bandwidth of antenna and peak gain is 5.2 dB. Thus the antenna covers the UWB range and it can also be used for bands such as 2.4/3.6/5 -GHz WLAN bands, 2.5/3.5/5.5GHz WiMAX bands and ...

Design of a compact dual band meandering line monopole antenna for WLAN 2.4/5.0 GHz applications

Recent years have seen development of variety of dual band antennas specifically for next generation wireless communications systems that will require increased bandwidth and higher data rates. These dual band antennas find application in mobile terminals, such as cellular devices or portable laptops, Wi-Fi dongles. Antennas employed in such systems have certain requirements: High gain, stable and omni-directional radiation pattern, reduced interference. This paper presents a compact dual band monopole antenna suitable for 2.4/5 GHz WLAN application. The antenna is fabricated on an FR4 substrate of size 20 × 30 × 0.8 mm3 and consists of multiple meandering lines connected to the 50-Ohm microstrip feed signal line to generate the desired dual resonance frequencies. Two impedance bandwidths, for S11≤−10 dB, of 240 MHz and 2570 MHz have been obtained from simulation results which show that the required bandwidths of IEEE 802.11b/g (2.4–2.485 GHz) and IEEE 802.11a (5.15–5.825 GHz) can be completely covered by the proposed antenna. Prototype of the proposed antenna shows good agreement between simulated and measured results. Improved bandwidth and nearly omni-directional radiation pattern of the proposed antenna at both resonance frequencies make it a viable choice for integration into modern portable devices. All simulations have been carried out using Ansofts HFSS ver. 15.0.

A Novel Dual Polarized Dual Feed Multi-Band Meander-Line Antenna for Mobile Applications

A multi-band dual polarized log periodic meander-line antenna is presented in this paper. The Ansoft HFSS 3D EM simulator is employed for design simulation. The proposed antenna is realized on a FR-4 Epoxy substrate with εr = 4.4 and tan ξ = 0.02. The size of the antenna is 14.5 x 20 x 1.59 mm 3 . The proposed antenna is fabricated and comparison between simulated and measured result for return loss has been observed and is found in good agreement. In addition to micro-strip transmission line feed, a capacitive probe feed has been introduced and enhancement in impedance bandwidth has been observed as compared to only transmission line feeding method. Small size of the antenna enables itself to be introduced in complex systems and can be used for various applications including GSM1800/1900, WCDMA2100 and LTE1800/2300/3700 TDD for mobile handsets and mobile assisted health applications.