Pipes are widely used in many industrial and mechanical applications and devices. Although there are many different constructions according to the specific application and device, these can show helical pattern, such as spiral pipes, wire-reinforced pipes/shells, spring-suspension, and so on. Theoretical modelling of wave propagation provides a prediction about the dynamic behavior, and it is f...

Drag reduction of an object is the major concern in many engineering applications. Experimental studies have been carried out on circular cylinder with helical grooves in a subsonic wind tunnel. Different cases of helical grooves with different pitches, helical groove angles and number of starts of helical groove on circular cylinder are tested. Experimental results show the drag coefficient is...

In this paper, a new antenna is presented which has an application in cellular telecommunication systems. The designed antenna works at the frequency range of 1900-2600 MHz which is able to cover 2G, 3G and 4G (LTE) services of the cellular telecommunication. In this paper, the micro-strip structure has been used to design the antenna. The shape of the patches is triangular where a peripheral r...

In this paper, a new method for designing an active dual-band dipole antenna is proposed. The operating frequencies of the proposed antenna are 150 and 450 MHz that are usually used in military applications. Using a series stub is the main idea in the proposed dual-band antenna, where it makes an independent resonance frequency higher than the main resonance frequency of a conventional dipole. ...

This paper presents a new design of a CPW-Fed multi bands planar antenna. This antenna can be integrated easily with passive and active elements. The proposed antenna is suitable to operate for GPS, PCS and WiMAX bands. Its entire area is 52.3x52.6mm2 and is employed on an FR-4 epoxy substrate and fed by a 50 Ohm coplanar line. The antenna parameters have been analyzed and optimized by using AD...

In this paper a microstrip antenna on a suspended substrate with capacitive feed is presented. capacitive feed is created by a slot within the rectangular patch around the feed point. The proposed antenna exhibits a much higher impedance bandwidth of about 47% (S11 < −10 dB). Effects of key design parameters such as the air gap between the substrate and the ground plane, the gap width between r...

This paper presents an E-ring shaped printed monopole antenna for UWB applications with dual notched bands performance. In order to generate single frequency band notch function, we applied a U-ring shaped monopole antenna, and by inserting a rectangular ring in the centre of it an E-ring shaped radiating patch created and a dual band-notch function can be achieved. The measured bandwidth of th...

In this paper a study of helical antenna resonating at high-frequency (HF) band with very compact structure is reported. The designed antenna's S11 parameter magnitude change frequency was calculated for different geometrical parameters. For each case, first, only single changed. Then fair comparison, multiple parameters were changed simultaneously while the total wire length set to be constant...

fresnel zone plate antenna (fzpa) was considered as a recieving antenna. an expression of electric field on axis of antenna produced by an incidente plane wave was found . the expression was used for calculation of gain, efficiency and optimum phase correcting function. several fzpa are fabricated and tested. experimental and theoretical results were compared and it was shown that there was a g...