FREQUENCY-RECONFIGURABLE MONOPOLE ANTENNA WITH WIDE TUNING RANGE FOR COGNITIVE RADIO

The design of a frequency-reconfigurable planar monopole antenna with a wide tuning range for cognitive radio is presented. The radiator of the antenna consists of two sections, Section I and Section II, which are connected together using a PIN-diode. Section I is meandering and responsible for generating a high-frequency band at about 2.69 GHz. Section II has a U-shape and, together with Section I, generates a low-frequency band at about 2.39 GHz. The PIN-diode is used to select whether only Section I or both Sections I and II together to work as the radiator for the antenna. The radiator has a very compact size of only 11.5 x 8.4 mm(2). Continuous tuning for the low- and high-frequency bands is accomplished by placing a varactor on Section I of the radiator. The varactor and the PIN diode are biased using very simple DC circuits. The frequency-reconfigurable antenna is studied, designed, and optimized using computer simulation. Measurement is used for verification of the simulation results. Results show that the antenna can be tuned from 2.69 to 3.0 GHz using Section I and from 2.39 to 2.62 GHz using both Sections I and II together. Using the PIN-diode, the antenna can achieve a wide tuning range of 2.39 to 3.0 GHz. The antenna performance in terms of tuning range, radiation pattern, realized peak gain, and efficiency is presented. The feeding cable used in measurement causes substantial discrepancies between the simulated and measured results. A simulation cable model is used to verify such cable effects. (c) 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:145-152, 2014