A Wide Spectrum Sensing and Frequency Reconfigurable Antenna for Cognitive Radio

Abstract

Abstract-A novel hybrid antenna capable of both spectrum sensing and frequency reconfigurability is proposed in this paper. The proposed hybrid antenna senses spectrum over a wide frequency range from 1 GHz-12 GHz and accordingly reconfigures its operating frequency in any of the four different frequencies, i.e., 2.1 GHz, 2.96 GHz, 3.5 GHz and 5 GHz. Since wideband response for spectrum sensing and each frequency state works independently, there is no interference among various signals. The wideband response for spectrum sensing is obtained by exciting semicircular arc having staircase-shaped slot in the ground plane. Frequency reconfiguration is achieved by electronic switching among various matching stubs. Both simulated and experimental results for the return loss, gain and radiation patterns are presented. The proposed hybrid antenna shows a measured return loss better than −20 dB in all the operating bands, a bidirectional radiation pattern and 4.8 dB gain in θ = 20 • and 120 • in E plane.

A Novel Reconfigurable Antenna With Separate Sensing Mechanism for Cr System

“…The proposed antenna will work for UWB mode if port 2 is activated, and it can switch its bandwidth over any one of the five NBs (case 1 -case 5 ) by activating port 1 . In literature, a number of antennas are reported in which a separate sensing antenna is designed without degrading the overall performance [2][3][4][5][6][7][8][9][10][11][12][13]. In all these designs, the numbers of reconfigurable features are limited to one or two.…”

“…These two antennas are integrated together on a single substrate so that they work simultaneously without interfering with each others' characteristics. In literature, a separate UWB antenna is used as sensing antenna, and then reconfigurable antenna changes its characteristics by mechanical [5], optical [6,7] or electrical [8][9][10][11][12][13] means. These antenna designs can smartly sense the spectrum and accordingly reconfigure either its frequency state or radiation pattern.…”

Two Port Integrated Reconfigurable Microstrip Patch Antenna

“…Integrated reconfigurable antenna which provides multiple selectable features meets the above said requirement. In [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], some design schemes are available in which two antennas are integrated on a solitary substrate to optimize the space utilization. In these reported schemes, small antennas are incorporated in huge sized UWB radiator either by reutilization of large printed area of UWB antenna as ground plane for the second antenna [4][5][6][7][8][9] or by placing the small sized antenna in electrically neutral area of UWB antenna [10][11][12][13].…”

“…All these designs are good and solve the problem of underutilization of large printed area of UWB antenna. However in all reported designs, the numbers of reconfigurable features are confined to either frequency reconfiguration or NB-WB reconfiguration [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. However, single reconfiguration feature is not sufficient for future communication devices.…”

A versatile reconfigurable antenna with integrated sensing mechanism

“…Further to decrease the system size, these two antennas must be optimally integrated on a single substrate. A lot of antenna designs have been already reported in the literatures which are compatible with CR [4][5][6][7][8], but only a handful of techniques based on integration concept of these antennas are reported in literature [9][10][11][12][13][14][15][16][17][18][19][20]. In all the reported designs, the numbers of reconfiguration features are limited and further upgradation of these antennas to increase the reconfiguration states are quite challenging because of limited space constraints on board.…”