Hi-VHF Circular Loop + Reflector

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Hi-VHF Circular Loop + Reflector

Hi-VHF Circular Loop with either Loop or Screen Reflector analyzed using 4nec2.

a) With Loop Reflector, Net Gain was 8 dBi on Ch7, dropping to 6 dBi on Ch13 with excellent SWR, except for small increase on Ch7.

Adding Loop Reflector increased Net Gain by 2-4 dB (less at high freqs) with more than 8.7 dB F/B (and F/R) using

Optimum Diameter=22-in for Half-Inch Copper Tubing. Best F/B (and F/R) is on Ch8-10.

Optimum Diameter=21.5-in for Quarter Inch Copper Tubing (QICT) was nearly as good, with more than 7.3 dB F/B (and F/R).
Smaller Circular Loop Element sizes not analyzed since a Square Loop (Quagi) would be easier to construct.

Loop Reflector dimensions are optimized for full Hi-VHF Band coverage.
Rescaling to optimize Ch7 will have only minor-moderate impact to Ch13 F/B, F/R and SWR.
However, rescaling to optimize Ch11-13 will degrade F/B, F/R and especially SWR on CH7-10.

b) EDIT (16 Sep 2009): Added analysis of alternative Hi-VHF Circular Loop with Minimalist 28" H x 34" W Screen Reflector:

Hi-VHF Raw Gain = 7.9 dBi, F/B & F/R Ratio = 11.5 to 15.2 dB and SWR (300-ohms) Under 3.2.

c) EDIT (5 Oct 2013): Added analysis of alternative Hi-VHF Loop with 40" H x40" W Screen Reflector to improve F/B & F/R Ratios:

Hi-VHF Raw Gain = 8.2 to 8.3 dBi, F/B & F/R Ratio = 13.7 to 15.5 dB and SWR (300-ohms) Under 2.7.

d) EDIT (15 Jul 2014): Added Circular Polarization analysis of alternative Hi-VHF Loop with 28" H x 34" W Screen Reflector.

Date(s): 15 July 2009. Album by holl_ands. 1 - 43 of 43 Total. 11771 Visits.

enlarge 0KB, 1024x840 1 Hi-VHF Circular Loop w. Loop Reflector - 3D View Loop to Loop Separation = 13-in	enlarge 0KB, 1024x696 2 Hi-VHF Circular Loop w. Loop Reflector Raw vs Net Gain vs SWR (300-ohm) for Half-Inch and QuarterInchCopperTubing (QICT).	enlarge 0KB, 1024x696 3 Hi-VHF Circular Loop w. Loop Reflector Dimensions are for a "balanced" design with EQUAL F/B and F/R at highest and lowest freqs.
enlarge 0KB, 1024x819 4 Hi-VHF Circular Loop w. Loop Reflector Raw Gain, F/B and F/R Ratios Optimum Diameter=22-in for Half Inch Copper Tubing (OD=0.514)	enlarge 0KB, 1024x819 5 Hi-VHF Circular Loop w. Loop Reflector - SWR Optimum Diameter=22-in for Half Inch Copper Tubing (OD=0.514)	enlarge 0KB, 1024x819 6 Hi-VHF Circular Loop w. Loop Reflector Impedance Half Inch Copper Tubing (OD=0.514)
enlarge 0KB, 1024x819 7 Hi-VHF Circular Loop w. Loop Reflector Raw Gain, F/B and F/R Ratios Optimum Diameter=21.5-in for Quarter Inch Copper Tubing	enlarge 0KB, 1024x819 8 Hi-VHF Circular Loop w. Loop Reflector - SWR Quarter Inch Copper Tubing	enlarge 0KB, 1024x819 9 Hi-VHF Circular Loop w. Loop Reflector Impedance Quarter Inch Copper Tubing
enlarge 28KB, 791x1024 10 Hi-VHF Circular Loop w. Loop Reflector Example 4nec2 File	enlarge 0KB, 855x1024 11 Hi-VHF Circular Loop 28x34 Screen Reflector 3D View	enlarge 0KB, 1024x849 12 Hi-VHF Circular Loop 28x34 Screen Reflector Front View [One small box = 0.5 inch] 23-in Diameter (Ctr-Ctr) QICT (Quarter Inch Copper Tubing) 28"H x 34" W Screen Refl. (1-in x 2-in Grid)
enlarge 0KB, 581x1024 13 Hi-VHF Circular Loop 28x34 Screen Reflector Side View [One small box = 0.5 inch] Loop to Reflector Separation = 13-in "Small note: Reflector's top looks 1..." View Comments...	enlarge 0KB, 489x1024 14 Hi-VHF Circular Loop 28x34 Screen Reflector Top View [One small box = 0.5 inch] Loop to Reflector Separation = 13-in	enlarge 154KB, 791x1024 15 Hi-VHF Circular Loop 28x34 Screen Reflector Example 4nec2 File
enlarge 147KB, 1024x686 16 Hi-VHF Circular Loop 28x34 Screen Reflector Hi-VHF Raw Gain = 7.9 dBi Hi-VHF F/B & F/R Ratio = 11.5 to 15.2 dB	enlarge 180KB, 1024x686 17 Hi-VHF Circular Loop 28x34 Screen Reflector Hi-VHF SWR (300-ohms) Under 3.2	enlarge 144KB, 1024x686 18 Hi-VHF Circular Loop 28x34 Screen Reflector Hi-VHF Impedance
enlarge 313KB, 1024x1024 19 Hi-VHF Circular Loop 28x34 Screen Reflector Azimuthal Patterns at 174 MHz	enlarge 318KB, 1024x1024 20 Hi-VHF Circular Loop 28x34 Screen Reflector Azimuthal Patterns at 198 MHz	enlarge 318KB, 1024x1024 21 Hi-VHF Circular Loop 28x34 Screen Reflector Azimuthal Patterns at 216 MHz
enlarge 319KB, 1024x1024 22 Hi-VHF Circular Loop w. Screen Reflector Right Hand Circular Polar. at 174 MHz	enlarge 321KB, 1024x1024 23 Hi-VHF Circular Loop w. Screen Reflector Right Hand Circular Polar. at 198 MHz	enlarge 326KB, 1024x1024 24 Hi-VHF Circular Loop w. Screen Reflector Right Hand Circular Polar. at 216 MHz
enlarge 136KB, 1024x686 25 Hi-VHF Circular Loop 28x34 Screen Reflector Ch2-6 + FM Band Raw Gain	enlarge 175KB, 1024x686 26 Hi-VHF Circular Loop 28x34 Screen Reflector Ch2-6 + FM Band SWR (75-ohms) is EXCESSIVE	enlarge 149KB, 1024x686 27 Hi-VHF Circular Loop 28x34 Screen Reflector Ch2-6 + FM Band Impedance
enlarge 326KB, 1024x1024 28 Hi-VHF Circular Loop 28x34 Screen Reflector Azimuthal Patterns at 54 MHz (Ch2)	enlarge 326KB, 1024x1024 29 Hi-VHF Circular Loop 28x34 Screen Reflector Azimuthal Patterns at 69 MHz (Ch4)	enlarge 337KB, 1024x1024 30 Hi-VHF Circular Loop 28x34 Screen Reflector Azimuthal Patterns at 87 MHz (Ch6 & Lo-FM Band)
enlarge 333KB, 1024x1024 31 Hi-VHF Circular Loop 28x34 Screen Reflector Azimuthal Patterns at 97 MHz (Mid-FM Band)	enlarge 338KB, 1024x1024 32 Hi-VHF Circular Loop 28x34 Screen Reflector Azimuthal Patterns at 108 MHz (Hi-FM Band)	enlarge 320KB, 1024x1024 33 Hi-VHF Circular Loop w. Screen Reflector Right Hand Circular Polar. at 186 MHz
enlarge 226KB, 975x1024 34 Hi-VHF Circular Loop 40x40 Screen Reflector 3D View 23-in Diameter (Ctr-Ctr) QICT (Quarter Inch Copper Tubing)	enlarge 360KB, 995x1024 35 Hi-VHF Circular Loop 40x40 Screen Reflector Front View [One small box = 1.0 inch] 23-in Diameter (Ctr-Ctr) QICT (Quarter Inch Copper Tubing) 40"H x 40" W Screen Refl. (1-in x 2-in Grid)	enlarge 137KB, 577x1024 36 Hi-VHF Circular Loop 40x40 Screen Reflector Top View [One small box = 1.0 inch] 23-in Diameter (Ctr-Ctr) QICT Loop to Reflector Separation = 14-in
enlarge 171KB, 1152x686 37 Hi-VHF Circular Loop 40x40 Screen Reflector Hi-VHF Raw Gain = 8.2 to 8.3 dBi Hi-VHF F/B & F/R Ratio = 13.7 to 15.5 dB	enlarge 203KB, 1152x686 38 Hi-VHF Circular Loop 40x40 Screen Reflector Hi-VHF SWR (300-ohms) Under 2.7	enlarge 240KB, 1152x686 39 Hi-VHF Circular Loop 40x40 Screen Reflector Hi-VHF Impedance
enlarge 305KB, 1024x1024 40 Hi-VHF Circular Loop 40x40 Screen Reflector Azimuth Pattern at 174 MHz	enlarge 305KB, 1024x1024 41 Hi-VHF Circular Loop 40x40 Screen Reflector Azimuth Pattern at 198 MHz	enlarge 305KB, 1024x1024 42 Hi-VHF Circular Loop 40x40 Screen Reflector Azimuth Pattern at 216 MHz
enlarge 141KB, 791x1024 43 Hi-VHF Circular Loop 40x40 Screen Reflector 4nec2 File

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Great details.
Best Love Quotes English
- Chi mo, Sat, 18 Mar 2023 10:40AM

holl_ands,

Did you notice the gain flatness of the screen reflector? I also noticed that it has a beamwidth of 70° down to about 5dB.

How do the results compare to a 21.5" (ctr-ctr) QICT driven element?
- Systems2000, Thu, 15 Oct 2009 11:38AM