An UWB to four sub-bands frequency reconfigurable CPW-fed disc monopole antenna

Abstract

An UWB to four sub-bands frequency reconfigurable CPW-fed disc monopole antenna is presented. A single pair of ring slot resonators is inserted to the CPW ground plane to achieve the reconfiguration, maintaining the original size unchanged. The proposed antenna is capable of switching between a wide operating band of 2.3 GHz -10.5 GHz and four different sub-bands, offering pre-filtering functionality to the system. Switches were employed at specific locations in the resonator to change its effective electrical length, hence forming different filter configurations. Antenna performances obtained from simulation and measurement results show a good agreement, which validates the proposed design approach. The antenna is potentially suitable for applications requiring dynamic band switching such as cognitive radios.

Compact, Frequency-Reconfigurable Filtenna With Sharply Defined Wideband and Continuously Tunable Narrowband States

“…The size of this optimized filtenna design is only 0.235 λ L × 0.392 λ L , where λ L = c/f L is the wavelength corresponding to the lowest frequency f L of its entire -10 dB operational frequency range. A direct comparison of the performance characteristics of the filtenna with those of the CR antennas reported in [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] is given; it establishes the fact that this filtenna is a simpler and more compact design. Moreover, its 36% frequency-agile fractional bandwidth is shown to be wider than the previously reported cases [17,18] without degrading the realized gain values.…”

“…Owing to their inherent tunable and dynamically-controlled features, frequency-agile and reconfigurable technologies have become practical approaches to empower both functionalities [2,3]. As a result, many years of effort have been devoted to designing reconfigurable antennas for CR applications [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

“…On the one hand, PIN diodes or GaAs field effect transistors are incorporated into an antenna to switch between its wideband state, which is used to sense the available spectra, and its multiple, discrete, fixed narrow-band states for communications [4][5][6][7][8][9][10][11][12][13][14][15]. On the other hand, PIN and varactor diodes are employed, respectively, to switch between the wideband and the narrowband states, and to realize continuous tuning amongst the various narrowband states [16][17][18].…”

“…The elements which provide the ON/OFF switching functions facilitate only a few, fixed narrow bands. One does not obtain a frequency-agile property which allows one to continuously shift the operational narrow-bands across the entire sensing band [4][5][6][7][8][9][10][11][12][13][14][15]. In contrast, employing continuously-controllable elements overcomes this issue.…”

“…Nevertheless, the related frequency-agile bandwidths are quite narrow (~ 20 %) and their configurations are not compact [17,18]. Moreover, to the best of our knowledge, the CR antennas that have been reported to date do not provide the necessary out-of-band rejection performance characteristics throughout the wideband state [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. It would be advantageous to effectively eliminate the impact of any signals that lie outside of the sensing spectrum, i.e., to have very sharp out-of-band rejection properties associated with the filter defining the sensing spectrum.…”