Frequency Reconfigurable Antenna for Portable Wireless Applications

In this paper,the design and experimental evaluation of a hexagonalshaped coplanar waveguide(CPW)-feed frequency reconfigurable antenna is presented using flame retardant(FR)-4 substrate with size of 37×35×1.6 mm3.The antenna is made tunable to three different modes through the status of two pin diodes to operate in four distinct frequency bands,i.e.,2.45 GHz wireless fidelity(Wi-Fi)in MODE 1,3.3 GHz(5G sub-6 GHz band)in MODE 2,2.1 GHz(3G Long Term Evolution(LTE)-advanced)and 3.50 GHz Worldwide Interoperability for Microwave Access(WiMAX)in MODE 3.The optimization through simulation modeling shows that the proposed antenna can provide adequate gain(1.44∼2.2 dB),sufficient bandwidth(200∼920 MHz)and high radiation efficiency(80%∼95%)in the four resonating frequency bands.Voltage standing wave ratio(VSWR)<1.5 is achieved for all bands with properly matched characteristics of the antenna.To validate the simulation results,fabrication of the proposed optimized design is performed,and experimental analysis is found to be in a considerable amount of agreement.Due to its reasonably small size and support of multiple frequency bands operation,the proposed antenna can support portable devices for handheld 5G and Wireless LAN(WLAN)applications.

Frequency reconfigurable antenna actuated by inflated triangular structure:Design and analysis

This paper proposes a frequency reconfigurable triangular antenna actuated by an inflated triangular structure.The open path antenna is transformed from an open type to a closed structure by inflating.Inflatable structures are easy to manufacture by fusing 2 inextensible membranes together along a defined pattern of lines.However,the prediction of their deployed shape remains a challenge.To solve the pattern changed problem,guided by geometric analyses and local buckle characteristics,the inflated triangular structure has been designed and verified by experiment and simulation.In the process of transformation of the antenna,the resonant frequency of the antenna is changed because this frequency is determined by the conformational change.The resonant frequency changes from GHz to kHz when the design of initial structure sizes is from millimeter to meter.The measured peak gains,the frequency,and the radiation direction are also reconfigurable by the initial size.Finally,the reconfigurable resonator array is presented,which is coupled to electric fields to absorb all incident radiation.In this work,the changed pattern design by inflating is applied to the antenna design,and its frequency reconfigurability is achieved.Through the electricity performance analysis of the reconfigurable antenna,precise manufacturing will be possible and provide guidance for manufacturing frequency reconfigurable antennas.

Ultrahigh frequency tunability of aperture-coupled microstrip antenna via electric-field tunable BST

A composite ceramic with nominal composition of 45.0 wt%（Ba0.5Sr0.5）TiO3–55.0 wt%MgO（acronym is BST–MgO） is sintered for fabricating a frequency reconfigurable aperture-coupled microstrip antenna. The calcined BST–Mg O composite ceramic exhibits good microwave dielectric properties at X-band with appropriate dielectric constant εr around85, lower dielectric loss tan δ about 0.01, and higher permittivity tunability 14.8% at 8.33 k V/cm. An ultrahigh E-field tunability of working frequency up to 11.0%（i.e., from 9.1 GHz to 10.1 GHz with a large frequency shift of 1000 MHz）at a DC bias field from 0 to 8.33 k V/cm and a considerably large center gain over 7.5 d B are obtained in the designed frequency reconfigurable microstrip antenna. These results demonstrate that BST materials are promising for the frequency reconfigurable antenna.

RF MEMS Based Reconfigurable Rectangular Slotted Self Similar Antenna

Wireless communication systems which require flexibility and reconfigurability in antenna systems faces main problems like antenna performance, size, weight and cost. A wide band Frequency Reconfigurable Rectangular Slotted Self Similar Antenna has been proposed in this paper. The rectangular slotted patch is repeated for two iterations at different scales and is separated by means of Radio Frequency Micro Electro Mechanical Systems (RF MEMS) switches in order to provide reconfigurability. The antenna can operate in three frequency bandsi.e. K-band, Ku-band and Ka-band by altering the states of RF MEMS switches. To avoid fringing effects and to improve antenna performance, quarter wavelength (λ/4) spacing is required between the antenna and the ground plane. However, a Reconfigurable Antenna requires different λ/4 spacing which is difficult to achieve using a common ground plane. So the Frequency Reconfigurable antenna is integrated with high impedance surface (HIS) like Electronic Band Gap (EBG) structures to suppress standing waves and surface waves with a unified profile thickness of 1.75 mm. The overall dimension of the proposed antenna along with RF MEMS Switch, feed element and HIS is about 8 mm × 8 mm × 1.75 mm. The simulated results of the proposed antenna reveal enhancement in antennas performance like Voltage Standing Wave Ratio (VSWR), Front to Back Ratio (FBR) and bandwidth when it is placed over HIS EBG. Also the radiation patterns of the proposed antenna when placed over EBG shows the suppression of side lobe and backward radiation.