Study of trapezoidal toothed log-periodic antenna fed through tapered microstrip line-to-coplanar stripline transition

The simulation and experimental studies of a wideband trapezoidal toothed log-periodic (balanced type) antenna excited through tapered microstrip (MS) line to coplanar stripline (CPS) transition (balanced type feed) are presented in this paper. Effect of the balanced type feed on the performance of antenna is discussed. The tapered MS line provides impedance matching between CPS transition, which is connected to antenna and 50-Ω coaxial cable. A quarter-wavelength radial stub at the output end of transition is responsible for field transition. The simulated reflection coefficient-frequency characteristic of the combination of the antenna and tapered MS line-to-CPS transition is compared with the corresponding characteristic of the antenna fed through microstrip-to-parallel strip balun. Further, the simulated input and radiation characteristics of the antenna fed through the proposed transition are also compared with corresponding experimental results. The antenna along with transition achieves simulated reflection coefficient bandwidth (reflection coefficient ≤ −10 dB) of 7.67:1 (0.9–6.9 GHz). The simulated peak realized gain and radiation efficiency vary in the range 0.25−5.6 dB and 71−95%, respectively over the operational bandwidth of the antenna-transition combination. The simulated input and radiation characteristics of the proposed antenna are nearly in agreement with the corresponding measured results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1671–1677, 2015