Microstrip Patch Array Antenna Pattern Design With Active Element

This paper proposed design of microstrip phased patch array antenna . The proposed design array is combination of linear and colinear feed with active element . The Active element pattern technique is applied for analyzing microstrip array, which reduces analysis problem and computation . The mutual coupling effect is added in the results of the proposed design . The FR-4 substrate with Dielectric constant 4.3 and loss tangent 0.019 is used for proposed design at resonant frequency of 3 GHz. Radiation characteristics, gain and return loss of the planar array antenna is simulated using Zeland IE3D simulation software . Operating frequency of these antennas are 3 GHz, 3.5 GHz and 5.4 GHz , so these design is suitable for S-band and C-band application. Kyewords :Microstrip patch , array antenna , Mutual Coupling, IE3D . I . INTRODUCTION The Microstrip patch array antenna are perfect choice for S-band and L-band various application due to following features, low profile, small size and conformability. But microstrip antennas suffer from bandwidth limitations. The bandwidth can be increased by adding lossy elements but it affects efficiency of the antenna. So the better method is to use array antenna. This design of microstrip array antenna is for Wimax and WLAN applications. The microstrip patch antenna is design at resonant frequency of 3GHz ,This designed added mutual coupling into account of simulated results . With this active array pattern the simulation time will be reduced and calculation will be easier . The spacing difference between two element is λ/4 for introducing mutual coupling between the elements . The common probe feeding is given to the centered active patch in my design based on slot coupling . Ring shaped slot is on the radiating patch and two rectangular slots on groung plane . Due to many advantages such as low profile , light weight , low cost ,ease of fabrication microstrip are widely applied in communication system . The simulated results of the proposed design achives a triple band 2.9 GHz to 3.2 GHz , 3.3 GHz to 3.6 GHz and 5 GHz – 5.6 Ghz (return loss less than -10dB). At this frequency band it is also useful in WiMAX[1] aplications and third band provide applications for wilreless local area network ( WLAN )[1] services such as IEEE 802.11a in the USA (5.15 to 5.35 GHZ,5.7 to 5.825GHz ) and HIPERLAN/2 in Europe (5.15 to 5.35 GHZ , 5.47 to 5.725GHz) . II.DESIGN METHODOLOGY AND PARAMETERS Theoretical analysis and calculation of a single microstrip patch is calculated with following equations [2] : The first step is to find the width , W of the patch at the resonant frequency using Equation 1 ; o r c 2 w= 2f ε +1 . (1) Where εr is the relative permittivity of the substrate, c is the speed of the light in free space and fo is the resonant frequency . Length of the patch is calculated by Equation 2; o eff c L= 2f ε . (2) Where , εeff is the effective dielectric constant of the substrate . To measure for the fringing effects , the actual length of the patch also includes the correction factor due to fringing effect . Actual length is given by Equation 3 ; r eff -2ΔL c L= 2f ε . (3) Correction factor can be found using the equation 4;