Defected Ground Structure Multiple Input-Output Antenna For Wireless Applications

In this paper,the investigation of a novel compact 2×2,2×1,and 1×1 Ultra-Wide Band(UWB)based Multiple-Input Multiple-Output(MIMO)antenna with Defected Ground Structure(DGS)is employed.The proposed Electromagnetic Radiation Structures(ERS)is composed of multiple radiating elements.These MIMO antennas are designed and analyzed with and without DGS.The feeding is introduced by a microstrip-fed line to significantly moderate the radiating structure’s overall size,which is 60×40×1 mm.The high directivity and divergence characteristics are attained by introducing the microstripfed lines perpendicular to each other.And the projected MIMO antenna structures are compared with others by using parameters like Return Loss(RL),Voltage Standing Wave Ratio(VSWR),Radiation Pattern(RP),radiation efficiency,and directivity.The same MIMO set-up is redesigned with DGS,and the resultant parameters are compared.Finally,the Multiple Input and Multiple Output Radiating Structures with and without DGS are compared for result considerations like RL,VSWR,RP,radiation efficiency,and directivity.This projected antenna displays an omnidirectional RP with moderate gain,which is highly recommended for human healthcare applications.By introducing the defected ground structure in bottom layer the lower cut-off frequencies of 2.3,4.5 and 6.0 GHz are achieved with few biological effects on radio propagation in human body communications.The proposed design covers numerous well-known wireless standards,along with dual-function DGS slots,and it can be easily integrated into Wireless Body Area Networks(WBAN)in medical applications.This WBAN links the autonomous nodes that may be situated either in the clothes,on-body or beneath the skin of a person.This system typically advances the complete human body and the inter-connected nodes through a wireless communication channel.

A SIZE-REDUCED LOG PERIODIC DIPOLE ANTENNA

A rectangle capacity patch was adopted as the resonance unit of the Log Periodic Dipole Antenna (LPDA) so as to realize the miniaturization of this aerial in this paper. Fifteen rectangle capacity patch units of different parameters were analyzed in this paper and three design laws of size-reduction were found. Accord-ing to these design laws, a 70% miniaturization ratio LPDA was designed and fabricated. The Voltage Standing Wave Ratio (VSWR) and pattern of the fabricated LPDA were measured. The results indicate that this size-reduction method do not deteriorate performance.

AN ULTRA-WIDEBAND ANTENNA FOR THE REINFORCED CONCRETE DETECTION

In this paper,an Ultra-Wideband(UWB) planar antenna is proposed for the reinforced concrete detection,which consists of a pair of planar waterdrop arms,a microstrip to coplanar parallel-strips transition and a shallow rectangular cavity.In order to overcome the disadvantages of the shallow cavity,some absorbing material is loaded to weaken the narrow-band effect of the cavity and the crosstalk interference.The simulated and measured results show that the proposed antenna has a large bandwidth from 0.48 GHz to 3.6 GHz with Voltage Standing Wave Ratio(VSWR) below 2 and a fractional bandwidth about 200% under the center frequency of 1.6 GHz,directional radiation characteristics and small late-time ringing in the time domain,which can be suitable for nondestructive detection of the reinforced concrete.