In this paper, a novel low-profile SWITCHABLE narrow and wide band circular ring sector slot antenna is presented for wireless applications. Adjustable operating frequencies especially with the ability of switching between narrow and wide band MODES could provide considerable immunity from jamming and noises. The combination of two wideband and six narrowband MODES are provided using PIN diode switches inserted on the relatively wide slot. The slot is etched in the ground plane with the size of 33×36 mm2. The results show the operating frequency bands of 3. 47-5. 48 GHz for the first wideband operation and 5. 2-7. 37 GHz for the second wideband operation with S11<-10 dB. In narrowband MODES, the operating frequencies can be adjusted from 2. 58-3 and 4. 88-5. 5 GHz for the first (f1) and second (f2) resonances, respectively. The proposed antenna is suitable for applications such as WLAN IEEE 802. 11a (5. 1 to 5. 8 GHz), WiMAX (2. 5– 2. 8 GHz), the ultra wideband (UWB) sub-band groups (3. 5– 5 GHz and 5– 6. 5 GHz) and also C-band radars.

In this paper, a frequency SWITCHABLE antenna design using genetic algorithms (GAs) for dual band WiMAX (3.5GHz) and WLAN (5.2GHz) applications is proposed. The area of the radiating patch element is divided into 2 mm square cells, with each cell assigned a conducting or non-conducting characteristic. To realize frequency reconfiguration, switches are incorporated into appropriate locations to activate/deactivate corresponding cells. The on/off states of the switches are represented by the presence or absence of conductor, respectively. Hence, the proposed approach allows the antenna to operate as mono-band or dual-band radiator according to the desired application. Further, measurements and simulations are carried out and a reasonable agreement is achieved.

The purpose of this paper is to design and simulate a unit cell that is wideband and multi-polarized for a reflect-array antenna. Bandwidth of structure is greater than 70% of X and Ku bands for satellite applications that reached from two printed dipoles and asymmetric arrow head shape in structure for multi electric and magnetic resonances and used thicker substrate for enhancement of BW by stack up of substrate with different layers. Depending on the antenna usage, the proposed structure can provide dual or triple polarization switching through the use of one or two control bits. Among the innovations of this structure compared to other activities, it can be said that the switching capability to support multiple polarizations occurs in a common wide bandwidth, or in other words, each of the switching MODES is not in different single frequency or a bandwidth of frequencies. Comparing the switching MODES of the proposed design with other existing control structures, the feature of maintaining the polarization of the feeding antenna or converting it to orthogonal polarization in different bits distinguishes the proposed structure. The proposed design has a new geometrical structure and considering that it can have the main polarization of the feeding antenna, its orthogonal polarization and even circular polarization in any switching mode, it has a relatively simple geometry, which reduces the complexity of the construction mechanism.