Hi-VHF Stacked ZigZag LPA using RG-59+

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Hi-VHF Stacked ZigZag LPA using RG-59+

Hi-VHF Band, Stacked Zig-Zag LPA, using Saw-Tooth Wire Elements.
Balun (4:1, 300 to 75-ohm coax transformer) connects between Top and Bottom Zig-Zags at small end (on right).
This version modeled with a simple VERTICAL FEED. SLANT FEED (between outer wire ends) had slightly higher gain (and messy trigonometry).
Stacked Zig-Zag has 1-2 dB loss versus SAME Geometry/Construction as a 14-Element LPDA...BUT is much EASIER to construct.

Date(s): 23 Dec 2008. Album by holl_ands. 1 - 19 of 19 Total. 3253 Visits.

enlarge 0KB, 1024x481 1 3D View - Stacked Zig-Zag LPA (Log Periodic Array) Antenna Optimum Vertical Separation Zsep = 3 to 5 inches.	enlarge 0KB, 1024x380 2 Stacked Zig-Zag LPA Dimensions - Top View RED is Bottom and GREEN is Top Zig-Zag. Keep clicking to see hi-rez. Click "OK" as usual to exit window.	enlarge 0KB, 1024x328 3 Stacked Zig-Zag LPA - View Along X-axis One small grid box = 1 inch. Note this version models a VERTICAL FEED. SLANTED FEED directly between Top & Bottom outer apexes works slightly better.
enlarge 0KB, 1024x819 4 Stacked Zig-Zag LPA - BARE RG-59 (no PVC Jacket) Zsep = 3.25 inches (2by4 on End) Gain = 8.2 to 8.6 dBi and F/B over 20 dB.	enlarge 0KB, 1024x819 5 Stacked Zig-Zag LPA - BARE RG-59 Zsep = 3.25 inches (2by4 on End) SWR less than 1.35 - Good Match to 300-ohm	enlarge 0KB, 1024x819 6 Stacked Zig-Zag LPA - BARE RG-59 Impedance vs Frequency Hi-VHF Band (Ch7-13) is 174 to 216 MHz. Plots extend 12 MHz above and below the band.
enlarge 0KB, 1024x819 7 Stacked Zig-Zag LPA - Wide Sweep Zsep Optimum Zsep = 3 to 5 inches.	enlarge 0KB, 1024x819 8 Stacked Zig-Zag LPA - Wide Sweep Optimum Zsep = 3 to 5 inches. Best F/B with reasonable Gain and SWR.	enlarge 0KB, 1024x819 9 Stacked Zig-Zag LPA - BARE RG-59 Wide Sweep Zsep SWR is CONSTANT vs Separation.
enlarge 0KB, 1024x819 10 Stacked Zig-Zag LPA - BARE RG-59 Wide Sweep Zsep GAIN slightly increases with separation, but F/B Ratio is best for Zsep = 3 to 5 inches.	enlarge 0KB, 1024x819 11 Stacked Zig-Zag LPA - BARE RG-59 Narrow Sweep Zsep Best F/B Ratio is for Zsep = 3 to 5 inches.	enlarge 0KB, 1024x819 12 Stacked Zig-Zag LPA Sweep Wire Conductivity (Cwire) Negligible - Only 0.03 dBi Gain over entire range of Copper, Aluminum and Copper Braid.
enlarge 0KB, 1024x819 13 Stacked Zig-Zag LPA - Zsep = 3.25 inches Sweep Wire Radius (Rwire) Most wire sizes have degraded SWR. Should use larger wire size, such as BARE Braided Shield (e.g RG-58/59).	enlarge 0KB, 1024x819 14 Stacked Zig-Zag LPA - Zsep = 3.25 inches Sweep wire radius (Rwire) Gain & F/B increase is negligible.	enlarge 0KB, 1024x819 15 Stacked Zig-Zag LPA - Zsep = 3.25 inches Sweep wire radius (Rwire) SWR slightly degraded for smaller wire sizes. Preferably should use Rwire = 0.09 or larger, such as BARE shielded coax (e.g. RG-59).
enlarge 0KB, 1024x819 16 Stacked Zig-Zag LPA - BARE RG-59 - Zsep=3.25 inches Average Gain Test = 0.9354	enlarge 0KB, 1024x747 17 Stacked vs Wedge Zig-Zag LPA: Gain	enlarge 0KB, 1024x747 18 Stacked vs Wedge Zig-Zag LPA: Gain and Front-to-Rear (F/R) Ratio
enlarge 5KB, 791x1024 19 4nec2 File: Hi-VHF (4.25-in) Stacked Zig-Zag LPA.

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