The Effect of Quarter-Wave Transformer Matching Network to the X-Circular Polarized Antenna

This technical paper presents the 2 design of xcircular polarized with slanted rectangular slot microstrip patch antenna by using single port in X-form is at 45 0 , 135 0 , 225 0 and 315 0 . The combination of 4 circular patches of Design 1 and the additional of quarter wave impedance matching technique for Design 2 have been used to design the X-circular polarized with slanted rectangular slot microstrip patch antenna. The designs are simulated using Computer Simulation Technology (CST) with dielectric constant, εr =4.3 and tan δ=0.019 and thickness of substrate, t=1.6mm. The simulation results such as return loss, bandwidth, gain, directivity and polarization have been compare

Performance Analysis of Concurrent Transmission with Reducing Handshakes in Multi-Hop Wireless Mesh Networks (WMNS)

The IEEE 802.11 Distributed Coordination Function (DCF) Medium Access Control (MAC) protocol continues to suffer from throughput degradation when directly applied in multi-hop Wireless Mesh Network (WMN). The Request-to-Send/Clear-to-Send (RTS/ CTS) signaling partially solved hidden node problems however the exposed node problems remain unaddressed. These exposed nodes lead to throughput degradation especially when the transmission in multi-hop networks is considered. The major reason for this poor performance is the restricted nature of the IEEE 802.11 MAC, which does not allow exposed nodes to initiates its transmission for the entire duration of ongoing transmission. Moreover, since multi-hop communication such as wireless mesh network transfer the data packet via intermediate nodes, the amount of control handshakes that take place at each intermediate node significantly reduce the throughput. This project proposes a set of enhancement to the existing IEEE 802.11 DCF MAC by enabling concurrent transmission by the exposed nodes and reduces the amount of handshakes required at every hop until the data packet reaches its destination. Analytical models are developed for analytical study of MAC protocols operating in multi-hop mesh networks and simulated over quasi-static Rayleigh fading channel. The multi-hop network performances are evaluated in terms of throughput and delay. The protocol outperforms the existing IEEE DCF MAC with more than 260% increase in overall throughput of multi-hop WM

Dual Polarization Single Port Inset Feed Microstrip Patch Array Antenna

This paper present the designs of array antenna from type of inset-fed microstrip patch antenna by using single port oriented at 45° and -45°. The antennas are capable to generate dualpolarization radiation pattern centered at 45° and -45°. Combinations of two patches using quarter-wave impedance matching technique has been used to designs the array antennas operate at 2.4 GHz. The designs are simulated using Microwave Office 2004 and were fabricated on FR4 substrate with a dielectric constant εr =4.7, tan δ =0.019 and thickness =1.6mm. The simulation and measurement result have been compared. The 3 design 1x2 array antennas yield a bandwidth greater than 5%. The gain of the proposed antennas is also stable with operated frequency. The result showed that the combination of more patches in array can improve the return loss and gain performances. 

Evolution of the Boolean function manipulation

Solving large systems of Boolean equations is a hard combinatorial problem. It can be greatly facilitated by preliminarily reducing the number of roots in separate equations which, in turn, leads to a reduction in the number of variables, equations and time complexity. This can have a significant effect upon the physical space and connectivity of electronic logic circuits when these are implemented using actual electronic devices or components. In this paper, we review various representation techniques, Boolean function manipulation issues and problems that are used in a practical design environment for digital systems design

Inverse phi Shape Sloted Planar Atenna for RFID Application

The new inverse phi slotted planar antenna is a dual-band linear polarized antenna. Recent communication requirements continue to push for more bandwidth capabilities for antenna systems. In order to communicate with tags from different countries, the RFID system requires a separate set of antennas for reader application. As a result, our environments are infected by diverse kinds of antennas. This inverse phi slotted planar antenna is designed to obtain dual-band RFID reader operation at the UHF bands of 860MHz- 960MHz and free ISM bands of 2.45 GHz. Therefore, this antenna is design to reduce the set of antenna in RFID system

Design High Gain PHEMT LNA for Wireless Application at 5.8 GHz

This research present a design of a higher gain (68.94dB) for PHEMT LNA using an inductive drain feedback technique for wireless application at 5.8GHz. The amplifier it is implemented using PHEMT FHX76LP transistor devices. The designed circuit is simulated with Ansoft Designer SV. The LNA was designed using inductive drain feedback, inductive generation to the source, and the T-network as a matching technique was used at the input and output terminal. The low noise amplifier (LNA) provides a noise figure 0.64 dB and gain (S21) of 68.94 dB. The output reflection (S22), input reflection (s11) and return loss (s12) are -17.37 dB, -15.77 dB and -88.39 dB respectively. The measurement shows the stability were at 4.54 and 3-dB bandwidth of 1.72 GHz. The input sensitivity is -92 dBm exceeded the standards required by IEEE 802.16