Application of Bacteria Foraging Algorithm in Designing Log Periodic Dipole Array for Entire UHF TV Spectrum

摘要

In this article, an attempt has been made to revisit the design of well-established log periodic dipole array (LPDA) in light of recent optimization technique, the bacteria foraging algorithm (BFA). Although there are many works published in the literatures based on various optimization techniques, this article deals with the optimization of the LPDA for the entire ultra high frequency (UHF) television (TV) spectrum (470-870 MHz) covering 400 MHz bandwidth and accommodating 49 channels. The challenges of this design lie in selecting suitable values of τ and σ for 134 frequency points for which different sets of all the output parameters such as gain, input impedance (Z_(in)), front-to-back ratio (FTBR), first side lobe level (FSLL), voltage standing wave ratio (VSWR), and so forth are obtained and then averaged over to get Gain_(av), Z_(inAav), FTBR_(av), FSLL_(av), and VSWR_(av) close to the desired values. These average values are used to design suitable fitness function. Another important aspect of this article is to provide exhaustive design details for LPDA using network theory that would couple to the BFA for getting the optimized number of elements to satisfy the desired values of Z_(inav), Gain_(av), FTBR_(av), FSLL_(av), and VSWR_(av), set as 50 Ω, 9 dBi, 40 dB, 40 dB, and 1.1, respectively. Moreover, this LPDA design considers the standard wire gauge dipole elements, which is just a very practical approach in the design procedure.