Electronically reconfigurable uni‐planar antenna for cognitive radio applications

A single port, electronically reconfigurable, uni‐planar antenna for cognitive‐radio (CR) systems is presented. This design effectively merges the time‐domain properties of tapered slot antennas with uni‐planar nature of coplanar waveguide (CPW). Two tapered slot antennas were excited through a CPW, which is embedded with a PIN diode controlled band‐pass filter. The prototype fabricated on Rogers ® RO3006 high‐frequency laminate with dielectric constant 6.5, loss tangent 0.002 and thickness 1.28 mm facilitates S 11 < −10 dB bandwidth from 1.6 to 6.0 GHz in the wide‐band mode and 3.39 to 3.80 GHz in the narrow‐band mode. The measured radiation characteristics show that the design is suitable for CR applications, in which a wide‐band antenna is used for spectrum sensing and a narrow‐band antenna for transmission. In addition, the measured time‐domain characteristics of the antenna including group delay, impulse response and fidelity factor are presented. These indicate that the proposed antenna can also be used for microwave imaging devices that are connected to the host through high‐speed worldwide interoperability for microwave access terminals. Finally, to assist antenna engineers working on industrial design, the housing effect on the prototype was also studied experimentally in frequency and time domains.