Multi-element Lowband Vertical Arrays - Kkn.net

The K9RS odysseyHow did this all start?• K9RS moved to Pennsylvania in 2005• Ray searched for 50 acres – but no go• Ray decided to settle for 4 acres• But the lot is unusual: 155 feet wideby about 1200 feet deep

Actually it started quite a while ago……when K9RS first started usingverticals in the Caribbean in‘86Or even before that ….

Ham Radio Magazine May 1985 May 1985

Nov/Dec 1985 NCJK9RS 80 meter antennafirst used on a 34 ft tower110 countries in 4 monthsBefore packet!

VP5KK9RS and AG9Awith 2 element 40M antenna

40M Feed point2 Ground barsTop• antenna• Coax centerBottom• Radials• Coax shield

VP5B the last operationMarch 2005K4ISVK9RSK4CN

VP5B legendary 160 antenna70 ft wire tied off to small storage shedAt front of property60 ft aluminum mastVery slight gain this directionHairpin match across feed point

Full size160VP5Bantenna

Now back to Pennsylvania

K9RS

Bent vertical elementsWhy use them?Convenient with short tower ormastExploit your tower for use in anarraySurprising results – notintuitive!

80 Meter Element(bent)ROPE86 ft towerWIRE 26 ftWIRE 40 ftTieRope50 ft

What is it?Bent 4 squareA wire 4 square hungfrom a relatively shorttower with the extralength bent in towardstower

80 meter bent 4 square 40 ft vertical, the rest slopestowards tower Comtek box Each element fed with 75 OhmRG-6 cable #14 Flexweave wire Each element started with 15radials 3/16 inch Dacron rope

Outside ring6dBiFull size vs.Bent 4 squareBent Verticals – very little difference !No tower modeled here

Full SizeBentBent w towerOutside ring6 dBiMinimal difference between (a) full size 4 square(b) bent 4 square and (c) bent 4 square with 146 ftequivalent height tower

160 Meter Element(severely bent)ROPEInsulators86 ft towerWIRE 102 ftWIRE 30 ftRope100 ft

Full size element 160Outside ring1.43 dBi23 degrees elModeled with MININEC real ground

Full size vertSeverely bent160m full size vertical vs. ‘severely bent’vertical •The full size qtr. wave has 1.43 dBi•The ‘severely bent’ has 2.2 dBi max. awayfrom sloping wire and 1.8 db front to back

Put up and phased 2 severely bentelements, diametrically opposed fromthe tower …But….a single element seemed to workbetter than the 2 element phased arrayEZNEC modeling reveals why!

160 Meter Element(severely bent)Effective towerheightWIRE 102 ftWIRE 30 ft

Single bent element becomes 4!6 dBi5.3 dB F/BModeled with 130 ft effective height tower

Severely bent element acts like 2 ele!4 dBi Gain10.4 dB F/BModeled with 140 ft effective height tower

Single element w/146 ft effective tower = 2 phased ele!Using 2 severely bent elements doesn’t improve anything!I found this out the hard way!2 elementSingle element

two phased severely bent 160m eleLeft element90 deg lead4.34 dBi10 dB F/BModeled with No tower in between

Two severely bent phased elementsperform only like a single elementMax gain 2.24 dBiLeft elementStill 90 degreeleadGain 2.19 dBiF/B 0.97 dBModeled With 135 ft effective height towerA BIG DIFFERENCE – THE TOWER HURTS PERFORMANCE!

Tower effective height calculation(electrical resonant length in EZNEC)StructureEffective height86 ft Rohn 45 and 14 ft 295.5 ftinch mastAdd 40 meter boom109 ftAdd top C31XR boom123 ftAdd 6 meter beam126 ftAdd bottom C31XR, etc130 ftAdd 40M & C31XR146 ftdriven elements

After trying 2 elements with poorperformance as compared to the singleseverely sloped vertical:tried 3 elements, and various combinationsNone seemed to work as well as a singleseverely bent elementBased on success with 80 M 4 Square, headded a 4 th element

A “4 square” doesn’t have to be square100 FeetN90 Feettower180 FeetK9RS 160 meter 4 “square” layoutand 80 meter 4 square layout

Full sizeIn this 80m model:Full size 80 Meter 4 square 6.0dBiBent with tower and 160 el 5.67dBiEffect of tower, bending, and one 160 element in front is minimal

160 meter ‘severely bent’ 4square 30 ft vertical, the rest slopes towardstower Comtek box #14 Flex-Weave wire 3/16 inch Dacron rope Each element started with 15 radials Each element fed with 50 OhmRG-8

33 ft fiberglass160 meter element

160 Meter 4 “square” ComparisonConsidering shape and tower interactionOuter ring6.88 dBiK9RS 5.82 dBiFull size squareBent rectangularBent with towerModeled with K9RS 146 ft effective height tower

160 M 4- “square” costAnchor kits and groundBar strips $100Wire and cable $250Dacron Rope $50Comtek 4 ACB-160 $420

First QSO VU7RG Jan 19 , 2007 just afterfinishing

Priceless

N3DXX Adding radials

This is the way to bury radials !

Results – this stuff works!K9RS on a narrow lot 1st in N. America M/S WAE 2007 1st N. America M/S CQWW SSB2007 2nd M/S IARU 2007 2nd ARRL DX SSB M/S 2008 5th ARRL DX CW M/S 2008 145 countries 160M, 207 on 80M

So what does this mean for you?If you can do anything you wantBut…This might not be usefulIf you don’t have as tall atowerIf you don’t have as muchspace

Lets look at a shorter50 ft tower2 2 ft masttowerC3S tribander single bent verticalelement

25 ft50 ft•Model of 80 meter severely ‘bent’vertical off a 50 ft tower•Use EZNEC to model tower and‘severely bent’ vertical

Bent 80 M verticalWith 50 ft tower3.27 dBi9.78 dB F/B

Bent element & tower vs. full sizeFull size 80‘Bent’ 80vertical1.8 dB gain over qtr. wave vertical9.8 dB front to back

Use drain spouts or flagpoles forIMAGINE: Put a Bent 4 squareon a much shorter towerEasy to install: 40 meter 4 squarewith a single 20 ft support on tinylotEasy to install: 80m and 40m bent 4squares with 40 ft tower supportApartment/condo dwellers: 20meter 4 square on a 10 to 20 ftsupport

Ideas and Future work Find optimal dimensions and baseplacements for bent verticals and differenteff. tower heights model and use tower-mounted parallel wiresand other techniques to lower/heighteneffective tower heights Explore horizontal and vertical patternsusing various geometries for single element,4 square

Thank YouAnd special thanks to:W2GD, W2RQ, WE3C, N3BB,N3DXX, AA5B, W5JAW, K9DX,K9HMB, N9NC, CTDXCCAnd of course Tim K3LR