Towards software defined antenna for cognitive radio networks through appropriate selection of RF-switch using reconfigurable antenna array

A compact six port antenna for better spectrum utilization efficiency in cognitive radio applications

“…However, the lower band edge frequency of Ant I (P3) from simulation is found to be 4.66 GHz. The difference between the lower band edge frequencies found from Equation (12) and simulation is 7.95%, which is acceptable as the lower band edge frequency calculated Equation (12) ensures an accuracy of 10% approximately. In the next step, a parametric analysis is done by varying the width of the ground plane of the Ant I (P3) of Figure 19 in positive X-direction.…”

“…Initially, a rectangular patch, which is fed by a tapered feed line producing a bandwidth of 4.65 to 8 GHz, is designed, as shown in Ant I (P3) of Figure 17. The lower band edge frequency of Ant I (P3) in the evolution of antenna associated with port 3 can be estimated by Equation (12) that is normally used for a rectangular monopole antenna. 19 f L Ant I P3 ð Þ = 7:2…”

“…Also, some other antennas for cognitive radio applications have been reported in the literature. [6][7][8][9][10][11][12][13][14][15] Most of the reported antennas in the literature are based on reconfigurable mechanisms that have unavoidable drawbacks like negative effects of the biasing lines, which affect the radiation characteristics when switches like PIN diodes, varactor diodes and RF MEMS are embedded into the radiating surface of the antenna, slow tuning, and power consumption. Moreover, it is difficult to implement these reconfigurable mechanisms in practice.…”

A wideband circularly polarized crossed dipole antenna with compact structure and frequency reconfiguration

“…The broadband frequency reconfigurable antennas have already demonstrated their potential in reducing interference and improving SNR while providing the high data rate. [8][9][10] At present, many methods are proposed to expand the antenna bandwidth, for example, the bandwidth can be expanded by responding multiple resonators simultaneously 11 or exciting multiple radiation modes on the same radiator. 12 Another way to achieve wideband operation is to employ a crossed dipole antenna, [13][14][15] in which a printed ring is introduced to supply a 90 phase difference.…”

Gain‐improved VHF broadband whip antenna loaded with radiation blades

“…However, in the trend of miniaturisation of antennas, whip antennas with limited height often belong to electrically small antennas in short wave band, whose input impedance is very sensitive to frequency, especially in low‐frequency band, the input resistance is small and the input reactance is large, which is difficult to match the impedance of feeder, and results in a narrow working band of antennas. In order to improve the bandwidth of whip antenna, scholars have proposed such methods as top load [2], RLC network load [3–5], matching network [3, 6–10] and fractal antenna [11, 12]. At present, loading and matching network technology are widely used, but the introduction of resistance brings new losses to the antenna and reduces the efficiency of the antenna.…”