4nec2 simulation results for Ken Nist's w1713a.ez file (as found in ant.xls on www.hdtvprimer.com/SIMS). Compared to VHF Raw and Net Gain charts (as posted on www.hdtvprimer.com/ANTENNAS/comparing.html). Latest version of 4nec2 refused to convert w1713a.ez file. Thanks are due to <300ohm> for using EZNEC to convert the file.
Ken Nist's ant.xls and w1713a.ez files do NOT show Big Gain Loss across Ch13, as depicted in VHF Raw and Net Gain Charts on hdtvprimer.
w1713a.ez measurements (prior to 2006) are somewhat different than recently purchased YA-1713. [Different sub-contractor???] Substituting larger radius elements measured in holl_ands YA-1713, a moderate Gain Loss is exhibited in upper half of Ch13.
Note that Ken Nist found 300-ohm impedance, vice 75-ohm for newer YA-1713 (holl_ands below) with different dimensions.
Date(s): 21 Jan 2009 NEW. Album by holl_ands. 1 - 24 of 24 Total. 2890 Visits.
enlarge 0KB, 1024x683 1 Ken Nist's w1713a.ez Comparisons - Raw Gain
Chart posted on hdtvprimer does NOT agree with ant.xls or w1713a.ez
enlarge 0KB, 1024x683 2 Ken Nist's w1713a.ez Comparisons - Net Gain
Element Sizes per holl_ands measurements result in significant Gain Loss across Ch13.
enlarge 0KB, 1024x683 3 Ken Nist's w1713a.ez Comparisons - SWR (For both 75 & 300-ohm assumptions.)
Nist assumed a 300-ohm Balun, whereas a 1:1 75-ohm Balun was readily identified (see photos).
enlarge 16KB, 1024x749 4 Raw Gain Chart from hdtvprimer
YA-1713 is line "F". Note Big Gain Loss across Ch13.
enlarge 18KB, 1024x712 5 Net Gain Chart from hdtvprimer [Includes loss due to SWR]
YA-1713 is line "F". Note Big Gain Loss across Ch13.
enlarge 0KB, 1024x495 6 Geometry View for w1713a.ez.nec
SOURCE is on Element#3, which is connected to Element#2 via a Crossover Transmission Line. TL Card assumes Zc=300-ohms and Lc=0.239776 meters (the distance between Element#3 and #2). (Negative impedance in TL Card denotes crossover)
All elements assumed by Nist to have 0.15 inch radius, although YA-1713 measured by holl_ands has 0.1925 inch radius for Element#3 and #2 and 0.1875 for all other elements.
enlarge 0KB, 826x1024 7 Raw Gain Chart from ant.xls Does NOT show Gain Loss across Ch13. YA-1713 is 2nd from top, gain increases 10 to 12+ dB
enlarge 0KB, 826x1024 8 Net Gain Chart from ant.xls YA-1713 line is MISSING from this chart due to a missing calculation cell. After correction, a Moderate Gain Loss for upper half of Ch13 is found (see chart above).
enlarge 0KB, 1024x819 9 Ken Nist's w1713a.ez file results
Average Gain Test = 1.0 (Excellent) [An assessment of the antenna model accuracy.]
Keep clicking on images to see higher rez. Click on "X" as usual to exit window.
enlarge 0KB, 1024x819 10 Ken Nist's w1713a.ez file results - Gain
