Search

The article presents a new reconfigurable antenna suitable for cognitive radio (CR) application under interweave paradigm. The new sleeve‐like geometry is improvised in the antenna for designing broadband sensing antenna and it consists of a hexagon shaped metallic patch along with modified coplanar ground plane structure and feed line (nonconventional coplanar waveguide feed). The p‐i‐n diodes are also incorporated with the printed antenna. By varying the switching states of the diodes, frequency hopping occurs over the frequency range 3.75 to 12.67 GHz (108.64% BW) which is better compared to the existing sensing antennas used for designing CR antenna. The antenna also offers suitable gain and omnidirectional radiation pattern over the operating range of frequencies. In addition to frequency domain analysis, time‐domain synthesis of the proposed antenna is also executed by using well‐known electromagnetic solver CST software. Moreover, the antenna is fabricated and measured parameters are in good accordance with measured results. [ABSTRACT FROM AUTHOR]

A wideband ultrathin frequency selective surface (FSS) structure is designed and developed for the complete X‐band. The design employs a metallic tetra‐arrow (two bidirectional arrows placed diagonally) and a circular split structure (metallic) in the top side and bottom side of RT duroid 5880LZ low‐loss substrate respectively. The proposed design has novel contribution in terms of significant reduction in electrical thickness (0.007λ0 which is corresponding to lowest operating frequency, 8.3 GHz) and wider transmission (S21) bandwidth (measured: S21 ≤ − 10 dB, 8.15‐13.2 GHz, 47.3%), covering entire X‐band due to cumulative loading of surface mount chip resistors in the top layer. The principle of operation of the proposed FSS further can be justified with its equivalent transmission line circuit model, which is based on microwave filter (band‐stop and band‐pass) topology for anticipating the desired characteristics. The FSS structure is further integrated with dielectric resonator (DR)‐slot hybrid antenna for enhancing the gain (measured: peak gain of 4.5 dBi without FSS and 7.8 dBi with FSS) of the antenna. The proposed FSS structure is fabricated and measured performance has very similar responses as simulated ones. [ABSTRACT FROM AUTHOR]