UHF 13-Element Twin-Boom (Layered) LPDA (Log Periodic Dipole Array) with Dimensions Optimized for Highest Gain (i.e. Sigma = 0.18) using nikiml's Python Scripts. Boom-Length = 36.7-inches. Detailed Dimensions found in below Word *.doc file (formatting errors in *.pdf).
UHF Raw Gain = 10.6 to 11.0 to 10.2 to 10.6 dBi, F/B & F/R Ratio Min = 25.0 dB and SWR (75-ohms) under 1.6.
Note that Max UHF Raw Gain occurs when Sigma = 0.213 (per Optimization) and 0.22 (per Parameter Study), but Quasi-Optimum Sigma = 0.18 is nearly SAME Performance, with much shorter Length, as analyzed here.
This Webpage includes Spread Sheets and Results Images for a Larger Number of Different LPDA's, illustrating how the Optimized, Max Gain increases as the number of Element Pairs is increased. Boom Length (and Gain) also increases as OPTIMIZED SIGMA increases [SIGMA is Normalized Spacing between Elements].
Note that there IS INDEED an OPTIMUM BOOM LENGTH for each choice of the number of Element Pairs, so there is NO ADVANTAGE to simply making the Boom any Longer and making the Boom SHORTER for a given number of Element Pairs REDUCES the Gain from Optimum. So you can say that a Longer Boom has more Gain....but it requires ADDING the RIGHT Number of Element Pairs. And since SIGMA also increases, the DENSITY of Element Pairs per Foot remains more of less the SAME.
Date(s): 13 May 2015. Album by holl_ands. 1 - 23 of 23 Total. 1708 Visits.
enlarge 171KB, 1024x742 1 13 & 7-Element Twin-Boom (Layered) LPDA Max Raw Gain vs Sigma Design Parameter [OPTIMIZED SOLUTIONS]
enlarge 93KB, 791x1024 22 UHF 13-El Twin-Boom LPDA - Sigma = 0.18 SUMMARY OF DIMENSIONS Very close to Optimum Sigma = 0.213, while being over 6-inches shorter.
enlarge 140KB, 791x1024 23 LPDA SPREAD SHEET Includes Dimensions for All Twin-Boom (Layered) Designs
