A novel reconfigurable slotted leaky-wave antenna (LWA) based on a substrate integrated waveguide (SIW) with a fixed-frequency beam-steering capability is presented in this paper. For improved compactness, the structure is based on a SIW technology with rectangular slots fed by associated coupling with plated-through holes (PTH).This represents a new feeding method for etched slots in SIW antennas. Each via is loaded with a pin diode on both sides frontend of the waveguide. The pin diodes are tunable by adjusting the DC bias voltage, which results in beam scanning at a fixed frequency of around 27 GHz. Thus an electronically controlled steerable SIW antenna has been designed and experimentally verified that the radiation angle varies from −33 • to +33 • .

Abstract-This paper presents the development and design of flexible and conformal printed monopoles antennas. The main objective is to control the level of radiation in broadside antenna from zero to a maximum by changing the curvature of printed board. Two printed antennas types are considered: thin wire and disk monopole. Furthermore, with the curving radius R increasing, the classical null on the broadside radiation pattern disappears gradually for both wire and disk. Increasing the curvature radius of conformal flexible antenna while keeping all other parameters same, wire monopole antenna becomes mismatched while the disk monopole antenna which remains matched for all radius of curvatures. The simulated results of various monopoles are compared successfully with measurements.

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AB ST RA CT :For lower frequencies (typically UHF), it is interesting to reduce the size of antenna. This paper presents a new structure of shortened antenna operating around 400 ?vlHz. The shortened monopole antenna using step change line is printed on Duroid with dielectric constant Er = 2,2 M,02 and thickness t = 0,8 f 0,02 mm. A shortening ratio ( ) of 51% is achieved. and the Babinet principle [ 11 allows to optimize easily the geometry and the choice of ratio of the sizes of lines. The calculated results of input impedance are. validated by experiment.A simple analysis based on the transmission line mode P applied to printed dipole antennas, INTRODUCTION:

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