A single layer substrate compact dual band rectangular micro-strip patch antenna with transmission line feeding is designed for Wireless Local Area Networks (WLAN) implementation. The desired antenna consists of a rectangular patch having two I-slots and a dielectric material with dielectric constant of 2.4. The use of cavity model with transmission line feed has the favor of low profile, high gain and wide bandwidth of the antenna. The antenna has overall size of 46.9 mm by 38.01 mm and gives bandwidth of about 90 MHz at resonance frequency of 2.45 GHz and that of 115 MHz at 4.1 GHz frequency with Defected Ground Structure (DGS). The antenna with DGS has return losses-21.25 dB at 2.45 GHz and-27.5 dB at 4.1 GHz where the gains are 6.70 dB for 2.45 GHz and 6.80 dB for 4.1 GHz. Finally the designed antenna has been simulated using Computer Simulation Technology (CST) microwave studio 2009 and it is comparable with manual computation results which are found to be suitable for WLAN applications.

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A dual band circular micro-strip patch antenna is designed and simulated to obtain electronic circuit miniaturization of an antenna in high speed wireless local area networks (IEEE 802.11a standard). The proposed antenna contains a substrate layer (FR-4 lossy) with a dielectric constant of 4.9 and there is a circular patch on the upper layer of the substrate. The coaxial probe feed is used to excite the desired antenna which reduces the spurious radiation and hence obtained good efficiency. Also the cavity model is used for larger bandwidth while maintaining the lower size of the antenna. An ‘E’ shaped slot is introduced in the radiating patch to obtain dual band resonance frequency with maximum current distribution on the surface. Finally the simulated results using Computer Simulation Technology (CST) microwave studio 2009 in this design are compared with manual computation results and are found to be suitable for WLAN applications.

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A dual band linearly polarized micro-strip antenna is designed and simulated to obtain electronic circuit miniaturization of an antenna in high speed wireless local area networks (IEEE 802.11a standard). The proposed antenna contains a substrate layer (FR-4 lossy) with a dielectric constant of 4.4 and there is a circular patch on the upper layer of the substrate. The coaxial probe feed is used to excite the desired antenna which reduces the spurious radiation and hence obtained good efficiency. It is shown that using cavity model 20% excess bandwidth can be achieved while maintaining the lower size of the antenna. An "E" shaped slot is introduced in the radiating patch to obtain dual band resonance frequency with maximum current distribution on the surface. Finally the simulated results using Computer Simulation Technology (CST) microwave studio 2009 in this design is compared with manual computation results which are found to be suitable for WLAN applications.

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A single band circularly polarized rectangular microstrip patch antenna has been simulated from the cavity equation at first and then the antenna design has been extended to 2 3 2 array. The length and thickness of the each element of the rectangular patch antenna with a slot in the center of the rectangular patch are 38 mm and 0.1 mm, respectively, which are comparatively smaller than our previously presented single-element circularly polarized microstrip antenna with an I-slot. In comparison to the bandwidth and efficiency of single element antenna, the quantity have increased about 39% and more than 90%, respectively, in the desired array antenna at the same resonant frequency that is 2.8 GHz. In this article, we also have studied and presented the return loss, bandwidth, gain, directivity, axial ratio of our aimed antenna. K E Y W O R D S cavity model, coaxial probe feed, microstrip antenna, return loss, single band antennaAbstract A novel compact X-band bandpass filter with a flat and wide passband as well as enhanced out-of-band performance is presented based on a source-load coupling architecture. The proposed architecture is symmetrically constructed of a pair of stepped-impedance feed structures and an embedded T-shape resonator, substantially improving the filter's frequency selectivity and passband performance. In order to obtain a broader stopband region, a set of stubs is loaded at the edges of the tapped open stub in the T-shape resonator. By utilizing a two-layer low temperature co-fired ceramic substrate, a prototype filter is

We have investigated the Vanadium- (V) substituted Ni–Zn–Co ferrites where the samples are prepared using the solid-state reaction technique. The impact of V5+ substitution on the structural, magnetic, dielectric and electrical properties of Ni–Zn–Co ferrites has been studied. The XRD analysis confirms the formation of a single-phase cubic spinel structure. The lattice constants have been calculated both theoretically and experimentally along with other structural parameters such as bulk density, x-ray density and porosity. The FESEM images are studied for analyzing the surface morphology. FTIR measurement confirms spinel structure formation. The saturation magnetization (M s), coercive field (H c) and Bohr magnet on (μ B) are calculated from the obtained M-H loops. The temperature-dependent permeability is studied to obtain the Curie temperature. The frequency and the composition dependence of permeability are also analyzed. Frequency dependent dielectric behavior and ac resistivity are also investigated. An inverse relationship is observed between the composition dependent dielectric constant and ac resistivity. The obtained results such as the electrical resistivity, dielectric constants and magnetic properties suggest the appropriateness of the studied ferrites in microwave device applications.