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A Study of Stacked Arrays of Yagi-Uda Antennas Jay Terleski, WX0B 1

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15m Example 120/90/65 2 WX0Bs 10 and 15 m stacks

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15m Example 3 A good model which applies to 20 and 10 meters will be a 4 element 23 foot design. Most antenna manufactures offer a similar antenna to this design. 40 meters we will will use 2 and 3 element beams common to Hams.

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Why do we stack yagis Gain Clean up pattern Control of Take-off angle Beam in multiple directions Suppress rain, snow, wind static 4

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Gain 5 Single 15m yagi at 125 feet 14.71 dbi gain @ 5

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Gain 6 125/95 stack with 17.01 dbi gain @ 6 degrees

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Gain 7 120/90 stack with 17.01 dbi gain @ 6 degrees125/95/65 stack 18.34 dbi gain @ 6 degrees

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Gain 8 125/95/65/35 stack 18.54 dbi gain @ 7 degrees

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Why do we stack yagis Gain Control of Take-off angle 9

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10 35ft lower one in stack 14 dbi @23 degrees

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Control of Take-off angle 11 65/35 lower two in stack 16.3dbi gain @ 12 deg

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12 95/65 middle two in stack 16.64 dbi @ 8 degrees Control of Take-off angle

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13 125/95/65 top 3 in stack 18.43 @ 6 degrees Control of Take-off angle

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Control of Take-off Angle 14 95/65/35 lower 3 in stack 17.54 dbi @ 9 degrees

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Control of Take-off Angle 15 125/35 upper lower in stack 15.91dbi @ 27 degrees

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Control of Take-off Angle 16 95/35 lobes at 9, 32, 54 degrees are possible

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Why do we stack yagis Gain Clean up pattern Control of Take-off angle 17

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BOP 18 43 m 32 m

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BIP both in Phase 19 42m/32m 125/95 17.3 dbi @ 6 degrees BIP

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BOP 180 degrees out 20 42/32 m 125/95 BOP 180 degrees 15 dbi 39 deg

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BIP / BOP 20a Comparison both in Phase and Both out of Phase

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4 high BOP or FOP 21 0 delay 180 delay

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Four in phase FIP 22 FIP 18.54 dbi gain @ 7 degrees

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FOP 23 FOP 17.67 dBi @ 17 degrees, bottom 2 BOP

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FIP / FOP 23 FOP 17.67 dBi @ 17 degrees FIP 18.54 dbi gain @ 7 degrees

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Some BOP rules Gain is always less at main lobe Phase delays that are not 180 do not work ! OR DO THEY??? 25

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Can other angles be used to change angles? 23 0 delay -90 delay

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FOP lower 2 -90 degrees 24 Smeared and loss of gain 15.52 dBi @ 7 degrees Loss of exactly 3db at 7 degrees

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Can other angles be used to change angles? 23 FIP 18.54 dbi gain @ 7 degrees 15.52 dBi @ 7 degrees -3db at lower lobe lost but at 25 degrees the gain is +20db more !

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Some BOP rules Gain is always less at main lobe But the gain may be better at all the nulls. Lets test this on two beams 25

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Fill in pattern by adding delay 15m 2 stack at 0 degrees15m 2 stack at -90 degrees phase relationshipdelay of bottom beam 17 dBi 26 15 dBi

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Apparatus 25

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Narrow beam 25 Target area

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Wide slurred pattern 25

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What are the effects of Boom length and spacing Example: Short booms vs. spacing C3 stack or any short Yagi. 27

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Boom length and spacing 28 C3 @ 95 feet 12.01 dBi @ 7 degrees

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Boom length and spacing 29 14.97 dBi gain @ 8 degrees - bad lobe goin UP! 30 ft space

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Boom length and spacing 30 Great pattern - gain 15.28 dBi @ 8 degrees 25 ft space

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Boom length and spacing Short booms vs. spacing C3 stack or any short Yagi. 31 Just right 15.46 dBi @ 8 degrees 27 ft space

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Boom length and spacing 32 How to calculate the best spacing based on boom length?

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Boom length and spacing 1.0 WL booms = 1 WL spacing.75 WL booms =.87 WL spacing.5 WL booms =.707 WL spacing.25 WL booms =.5 WL spacing Short booms are very critical, model it to be certain. 33 S (WL) = ( Boom Length in WL)

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What about stacking Dissimilar antennas? Matching technique - are they the same? Driven element offsets must be know. Baluns are they the same? 34

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Dissimilar antenna stacks It can be done with certain precautions Example 3 ele with 4 ele 15 m. Same match, same balun 34 3 foot offset

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Dissimilar antenna stacks 35 Slurred pattern less gain 15.7 dbi @ 6 degrees

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Dissimilar antenna stacks 36 3 feet / 44.4 ft (WL) X 360 degrees = 24.3 degrees of delay is required to put these antennas in phase. 3 feet X.66 (VF of RG213) = 1.98 feet of coax would need to be added to the leading driven element. Lets correct the model by adding in the delay line and see the resulting pattern

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Dissimilar antenna stacks 37 Well defined nulls, more gain, 17.03 dBi @ 6 degrees a gain of 1.33 dBi

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Dissimilar antenna stacks 37 Well defined nulls, more gain, 17.03 dBi @ 6 degrees a gain of 1.33 dBi Slurred pattern less gain 15.7 dbi @ 6 degrees

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Dissimilar antenna stacks 37 What if Beams, Matching and Baluns are not the same? 3 foot offset Gamma matched balun X Hairpin matched & balun Y

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Dissimilar antenna stacks 37 O-Scope, equal feed lines, and a friend are needed.

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Dissimilar antenna stacks 37 Measure the angle of delay needed to align pattern Build a coax delay line and add to the leading antenna’s feed line.

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Horizontal Stacking 38 Y

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Horizontal Stacking 39 PY5EG 10 Meter H frame Stack

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Horizontal Stacking 40 PY5EG 10 Meter H frame Stack Putting it together

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Horizontal Stacking 41 17.76 dBi gain 5 degreesRoster tails as expected 84 foot Separation 125 ft tall - TOO WIDE

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Horizontal Stacking 42 16.5 dBi gain 5 degreesRoster tails as expected 24 foot Separation 125 ft tall

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Horizontal Stacking 43 16.5 dBi gain 5 degrees14.66 dBi 5 degrees One 15 m beamTwo 15m Beams

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Horizontal Stacking & Vertical Stacking 44

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Horizontal Stacking 45 20.16dbi @ 6 degrees Optimized at.75 WL wide 1 WL tall 125/82 ft - 2KW into this array = ERP 200,000 Watts!

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Horizontal Stacking 46 Is EASY What if we turn the antennas 45 degrees on two towers

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47 X Y 34 feet 24 feet Horizontal Stacking

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48 IN Phase BIP = 15.95 dbi at 26 degrees Not what we want

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Horizontal Stacking 49 Delayed 180 degrees 17.38 dbi @ 5 degrees

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50 X Y 34 feet Spacing is.75 WL between driven elements Horizontal Stacking

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51 BIP 16.1 dBi @ 5 degrees close but.........

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Horizontal Stacking 52 16.5 dBi @ 5 degrees with a delay of 298 deg. Drive impedance varies as delays are changed

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Issues With Stagger Types That Turn 53 Close coupling is a problem Drive impedance vary widely as the array turns Matching will be a problem - very difficult to adjust This type of array is probably not suitable unless everything remains fixed as in an H-Frame or parallel tower single direction arrays More work needs to be done on LAPA type arrays for amateur work

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What Happens When I Beam in Multiple Directions? 54 Will rotating a Yagi 180 degrees in a stack cancel the forward pattern intended? Or will it allow the forward pattern to survive? Will rotating a Yagi in a stack achieve the intended pattern? That is, to beam in two directions at once? Or will it mess up the pattern?

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Multi-direction Beaming 55 Rotate this beam 90 and 180 degrees

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Multi-direction Beaming 56 Same direction - 3 high 6 degrees AZ pattern - 18.46 dBi gain

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Multi-direction Beaming 58 Middle rotated 90 degrees - 14.86 a loss of 3.6 dBi this is fine

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Multi-direction Beaming 59 Rotate 180 degrees - 15.84 dBi forward loss of 2.62 dBi forward F/B is now only 8.2 dB - This is effective and expected

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Multi-direction Beaming 60 Will rotating a Yagi in a stack achieve the intended pattern? That is, to beam in two directions at once? Yes, all beams in a properly spaced stack may be rotated individually without regard to cancellation. Will rotating a Yagi 180 degrees achieve the intended pattern? Yes, all three are fine to rotate.

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Summary - GAIN VERTICAL STACKS must be properly spaced Gain of 2.2-3 dB from adding second antenna Gain of 1.5-2 dB by adding a third antenna Gain of.5 - 1 dB by adding a fourth antenna 61

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Summary -Take off Angle Switching allows control of take off angle including BOP Angle of lobes can be bad due to poor spacing of yagis Stack lobe will always slightly higher than top yagi alone 18-20+ dB of difference can be seen from peak to null - This is more important than the raw gain of the array! Intentionally adding phase delay to one antenna can widen the main lobes to create a larger target and minimize nulls 62

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Summary BIP/BOP BOP useful for gaining high angle lobe from a 2 high stack at the sacrifice of only 3db of max stack gain This could be a secret weapon in SS and NAQP contests A high stack can be made to act like its close to the ground 63

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Summary - Pattern Stacks can clean up high angle unwanted lobes Separation space and boom length are closely related Always model the intended stack for lobe anomalies due to spacing Rotating an antenna 90 degrees or 180 degrees is an effective way Intentionally slurring a pattern can increase the target area 64 to beam in two or three directions at once.

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Example - 40 meter stack 65 How does a 3 ele full size 40 meter beam compare to a stack of shorty 40 meter beams like the CC 420?

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Example - 40 meter stack 66 12.56 dBi @ 13 degrees 145’ 3 ele 40m full size 12.54 dBi @ 14 degrees 99.8% efficient

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Example - 40 meter stack 67 10.98 dBi @ 13 degrees 72 % efficient Shorty 40 145’ 10.88 dBi @ 13 degrees 72 % efficiency Shorty 40 145’

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Example - 40 meter stack 68 13.08 dBi @ 16 degrees +.54 dB over full size Shorty 40 Stack, 145/70’

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Example - 40 meter stack 68 13.08 dBi @ 16 degrees +.54 dB over full size 12.54 dBi @ 14 degrees

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Summary - 40 meter stack Shorty 40 stacks are VERY effective in gain and pattern Shorty 40 stacks equals or betters a single 3 element full A full size 40 stack RULES but a shorty 40 stack is not bad! 69 Shorty 40 stacks have better pattern than a 3 ele FS beam More flexibility, beam in two directions, more angles Much easier to maintain size 40m beam

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Other Benefits of Stacking Snow, Rain, wind, ionization static can be eliminated or reduced by taking the top antenna out of a stack Corona discharge points are on the top beam 70

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W7GG 180 ft rotating tower 3 - KT34XAs 2 - 3 ele full size 40s 71

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K3MM 3 - KT34XAs 72

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73 N0AVW4ZV

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74 N5CQA61AJ

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75 WX0B

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Side Mount Clearance 25G44” 45 G 56.5” 55G58” X 2X Antenna swing arm side mount Tower legs

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A Study of Stacked Arrays of Yagi-Uda Antennas Jay Terleski, WX0B 75 QUESTIONS

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Thank You All - You’re the Best Customers in this World!

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