Microstrip-Fed Circular Disc Monopole Antenna with Defected Waveguide Structure

This paper presented the microstrip-fed circular disc monopole antenna with defected waveguide structure. First, the microstrip-fed circular disc monopole antenna was designed. Next, the monopole antenna was designed with waveguide and lastly followed by the defected waveguide structure where the uniplanar compact (UC) structure was used. CST Microwave studio software was used for simulation and parametric studies process. Initially, the microstrip-fed circular disc monopole antenna was designed to achieve return loss less than -10dB for wideband frequencies. Then, the gain and directivity was improved with the integration of waveguide. The highest directivity of 11.38dBi found at 13.5GHz. However, low efficiency and narrower bandwidth were obtained. Next, uniplanar compact defected waveguide structure (UC DWS) was designed at inner surface of waveguide. The bandwidth achieved 3.09GHz where it covered from 10.91GHz to 14GHz. Meanwhile, the directivity maintained higher than the monopole antenna with highest directivity of 8.84dBi at 10GHz. The gain was also improved from 11GHz to 14GHz with highest gain of 6.38dB occurred at 13.5GHz

CPW-Fed Circular Disc Monopole Antenna with Defected Waveguide Structures

This paper presented a parametric study on coplanar waveguide-fed (CPW-fed) circular disc monopole antenna with defected waveguide structure (DWS). The CPWfed circular disc monopole antenna was designed to cover wideband frequencies. Afterward, the monopole antenna was attached to a waveguide with a uniplanar compact defected waveguide structure (UC DWS). The simulation design and parametric studies were done by using the CST Microwave studio software. Initially, the CPW-fed circular disc monopole antenna was designed to achieve return loss of -10dB from 2.36GHz to 10GHz. The directivity has improved significantly when the monopole antenna was attached to a waveguide where the highest directivity was 9.83dBi at 8.5GHz. However, narrower bandwidth and lower efficiency were achieved. It achieved a bandwidth of 0.49GHz and highest efficiency of -1.76dB at 8.5GHz. The UC DWS was then designed on the inner surface of the waveguide with smaller dimension with 6.25 x 6.25mm 2 and a small gap of 0.3mm. The directivity and gain have been improved. The highest directivity and gain were 7.10dBi at 8.5GHz and 5.42dB at 6.5GHz respectively. The bandwidth was 3.66GHz where it covered from 6.34GHz to 10GHz

A novel green antenna phase-shift system with data acquisition boards

A novel green phase shifter system is proposed in this research. The system is developed by a combination of reconfigurable beam steering antennas and data acquisition (DAQ) boards. A combination of two reconfigurable beam steering antennas, located side-by-side, forms a spatial configuration structure with a fabricated ‘green’ element plank of rice husk placed in between. The concept of a spatial configuration technique has been ‘mutated’ by shifting the structure of spiral feed line and aperture slots of first beam steering antenna by as much as 45 ◦ . The PIN diode switches connected to the DAQ boards enable the intelligent capability of the spatial antennas. The activation of certain degree radiation patterns of either the first beam steering antenna or the second beam steering antenna depends on the memory of the DAQ boards — Beam Manager. When an intruder comes from the cardinal angles of 0◦/ 360◦, 90◦, 180◦, or 270◦, its range and angles’ location will be automatically detected by the first antenna through the output ports of the 1st DAQ: P1.0, P1.1, P1.2, and P1.3. The second antenna is then activated by the output ports of the 2nd DAQ: P2.0 up to P2.3, to adaptively maneuver the beam towards four different ordinal directions of 45◦, 135◦, 225◦, and 315◦

Single Feed Square Aperture Circular Polarized Antenna

In recent years, circular polarized antennas become more important in wireless communication systems because of the ability of radiating circular polarized wave. In this paper, the design of single-feed square-aperture antenna with and without reflector towards the circular polarized antenna performance is presented. The antenna made of square ground plane, square-aperture and a probing strip feed by using microstrip transmission line. The design has achieved a target axial ratio, which is less than 3 dB at frequency range of 4 GHz to 6.5 GHz. When a square ground plane reflector is integrated on the CP antenna for the unidirectional pattern, the presented antenna enhanced gain about 8 dB

The Effects of Nano Fillers on Space Charge Distribution in Cross-Linked Polyethylene

The performance of polymeric insulation will be distorted by the accumulation of space charge. This will lead to local electric field enhancement within the insulation material that can cause degradation and electrical breakdown. The introduction of nanofillers in the insulation material is expected to reduce the space charge effect. However, there is a need to analyze potential nanofillers to determine the best option. Therefore, the objective of this research work is to examine two types of nanofillers for Cross-Linked Polyethylene (XLPE); Zinc Oxide (ZnO) and Acrylic (PA40). The effects of these nanofillers were measured using the Pulsed-Electro Acoustic (PEA) method. The development of space charge is observed at three different DC voltage levels in room temperature. The results show that hetero charge distribution is dominant in pure XLPE materials. The use of both nanofiller types have significant effect in decreasing the space charge accumulation. With nanofillers, the charge profile changed to homo-charge distribution, suppressing the space charge formation. Comparisonbetween both the nanofillers show that PA40 has better suppression performance than ZnO

Analgesic efficacy and safety of peri-operative pregabalin following radical cystectomy: A dose grading study

AbstractPurposeAdding novel drugs like pregabalin to analgesic regimens might reduce postoperative pain, total opioid consumption and side effects, this study compares multiple doses of pregabalin for postoperative analgesia following radical cystectomy.MethodsThis study is registered at www.clinicaltrials.gov at no.: NCT02724293. Sixty patients were randomized into 4 groups: Group I: control (placebo) group, Group II: received pregabalin 300mg 2h preoperatively, Group III: received pregabalin 300mg 2h preoperatively and 12h thereafter, Group IV: received pregabalin 600mg 2h preoperatively. Postoperative pain, time to first request of analgesia, and total morphine consumption were recorded.ResultsVAS was significantly reduced in groups II, III, IV in comparison with group I immediately postoperative, and after 2h (P<0.05). Sedation score was significantly higher in groups II, III, IV compared to group I immediately postoperative (P<0.05). First request of analgesia was significantly delayed in groups II, III, IV compared to control group (P=0.000). Total analgesic consumption was significantly reduced in groups II, III, IV compared to group I (P=0.000). Group IV showed a significantly higher incidence of dizziness compared to group I.ConclusionPeri-operative pregabalin at doses of 300mg and 600mg reduced postoperative opioid consumption and prolonged time to first request of analgesia in patients who underwent radical cystectomy, and a single preoperative dose of 600mg is superior in analgesia to others, without serious side effects

Effect of Single Complimentary Split Ring Resonator Structure on Microstrip Patch Antenna Design

This paper had been comparing the performance of the normal patch antenna with single complimentary SRR patch antenna. Four different shapes of single complimentary split ring resonator structure had been incorporated into the microstrip patch antenna - square, circular, triangular, and rhombic. This simulation works had been done in CST Microwave Studio simulation software. The operating frequency of this antenna is 2.40 GHz for Wireless Local Area Network (WLAN) application.The parameters that considered in these works are return loss,resonant frequency, input impedance, gain, radiation pattern and bandwidth. The focusing parameter is to achieve the best gain performance that obtained from the single complimentary split ring resonator patch antenna. The addition of square SRR onto patch antenna will improve the gain from 6.334 dB to 6.508 dB

Rhombic Split Ring Resonator (R-SRR) Structure on Rectangular Patch Antenna Design

Abstract- This work focusing on the effect of the complementary rhombic split ring resonator (R-SRR) structure of gain, return loss and the radiation pattern the rectangular patch antenna design. The basic rectangular patch antenna design had been simulated in CST Microwave Studio simulation software. Then, the single unit of the R-SRR had been added into the patch antenna design. The targeting frequency of this antenna is 2.40 GHz for Wireless Local Area Network (WLAN) application. Compared with the conventional microstrip patch antenna with the same aperture size, the performance gain of the patch antennas is improved obviously and suitable for targeting frequency of 2.40 GHz. The parametric studies done this work work are the different variation pattern of R-SRR, different distance between two RSRR structure and different size of R-SRR