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In this paper presents nano-composites based on polyester (PE) matrix with multi-walled carbon nanotubes (MWCNTs) as fillers have been developed for microwave absorbing materials. The MWCNTs/PE composite samples were fabricated with different weight ratio of MWCNTs (3 wt%, 5 wt%, and 10 wt%). The electromagnetic properties of different MWCNTs/PE composite have been determined by using rectangular waveguide technique and Agilent material measurement software. Moreover, the reflection loss (microwave absorption) of MWCNTs/PE composite have been calculated based on the basis of transmission line theory. The performance of electromagnetic properties and microwave absorption of MWCNTs/PE composite were analyzed in X-band frequency. The dielectric loss properties of the composite are increse with increasing in MWCNTs weight ratio. The microwave absorption results show that such 3 wt% MWCNTs/PE composites sample with 4 mm thickness has achieved less than -10 dB values (< 90 % microwave absorption) of reflection loss.

This paper is to study the performance of rice husk and rice husk ash (RH-RHA) mixture material as a microwave absorber. The microwave absorption and dielectric properties, ε of RH-RHA mixture with different ratio were investigated in microwave frequency region 8.2 to 12.4 GHz (X-band). A waveguide transmission line method (Nicholson-Ross-Weir) was used to measure the complex permittivity of RH-RHA with different weight ratio mixture. The RH-RHA microwave absorbers were designed and simulated in CST-MWS. The various ratio RH-RHA mixtures show the different dielectric properties and the microwave absorption was investigated. The 60%RH-40%RHA microwave absorber has the best microwave absorption 46-76%. [ABSTRACT FROM AUTHOR]

This paper presents the dielectric properties of rice husk and carbon nanotubes (RHCNTs) composites materials. The RHCNTs composites materials prepared with various weight ratios of rice husk with CNTs 0-10 wt%. The length, width, and thickness of each RHC-NTs composite sample are 15.799 mm, 7.899 mm, and 5mm was fabricated. The rectangular waveguide technique was used to measure the complex relative permittivity of the RHCNTs composites materials. The conversion of s-parameters to complex relative permittivity parameter is computed by using 85071E Agilent technology software which using a transmission line technique consists of a network analyzer to perform the conversion to complex relative permittivity, εr. The complex relative permittivity is represented in terms of both the real and imaginary parts of permittivity in Ku-band frequency. The conductivity of RHCNTs shows increasing when the ratio of CNTs mixture increases. The materials, their dielectrics properties measurement result over 12.4-18 GHz frequency range are discussed. [ABSTRACT FROM AUTHOR]

The microwave industry has shown increasing interest in electronic ceramic material (ECM) due to its advantages, such as light weight, low cost, low loss, and high dielectric strength. In this paper, simple antennas covered by superstrate layers for 2.30 GHz to 2.50 GHz are proposed. The antennas are compact and have the capability of producing high performance in terms of gain, directivity, and radiation efficiency. Bismuth titanate with high dielectric constant of 21, was utilized as the ECM, while the superstrate layers chosen included a split ring resonator and dielectric material. The superstrate layers were designed for some improvement in the performance of directivity, gain, and return loss. The proposed antennas were simulated and fabricated. The results obtained were small antennas that possess high gain and high directivity with 360°, omni-directional signal transmission that resonant types of conventional dipole antenna cannot achieve. The gain of the antenna with the superstrate layer was enhanced by about 1 dBi over the antenna without a superstrate layer at 2.40 GHz. [ABSTRACT FROM AUTHOR]

We investigated a dielectric resonator ceramic microstrip patch antenna. The antenna was formed using barium strontium titanate (BST), which had a dielectric constant of 15. A new approach, i.e., the use of a high temperature dielectric probe kit, was used to determine the dielectric constant of BST. A computer simulation technology (CST) microwave studio was used to simulate the BST array antennas, taking into consideration the dielectric constant. We also measured the gain of the antennas loaded with two-, four-, and six-element arrays of the BST antenna and found that the gain of a six-element BST array antenna was enhanced by a gain of about 1.6 dB over the four-element BST array antenna at 2.3 GHz. The impedance bandwidths of these BST array antennas for voltage standing wave ratio (VSWR) < 2 were in the application ranges, i.e., 2.30 to 2.50 GHz, established for Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN). Compared with the conventional array antenna with the same aperture size, the performance of the antenna obviously was improved, and the design is suitable for array applications, including base stations, for example. [ABSTRACT FROM AUTHOR]

In this paper is showing about Beam Switching Antenna that able to shift the antenna direction by using four microstrip antenna and aluminum. The antenna is using FR-4 and the saiz is 40 mm x 78 mm. By using aluminum it able increase the gain from 5.269 dB to 8.128 dB while the directivity is from 7.126 dBi to 11.09 dBi. With this antenna it able to control the direction of the radiation pattern up to four location. [ABSTRACT FROM AUTHOR]