~ ~ K9AYK9AY Loops ~ Loops ~

Thanks Gary Breed, K9AY!Thanks Gary Breed, K9AY!

de N4GG

© Harold E. Kennedy, 2008

More than you wanted to More than you wanted to know?know?

What is a K9AY loop?What is a K9AY loop? How well do they work?How well do they work? DemoDemo How to make oneHow to make one Build & test your own matching Build & test your own matching

transformertransformer What’s Important and What Isn’tWhat’s Important and What Isn’t Grounds, Ground, LocationGrounds, Ground, Location Make vs. BuyMake vs. Buy

HistoryHistory ““The K9AY Terminated Loop-A Compact, The K9AY Terminated Loop-A Compact,

Directional Receiving Antenna,”Directional Receiving Antenna,” QSTQST, Sept. , Sept. 19971997

Performance varied: Great, Fair, PoorPerformance varied: Great, Fair, Poor Most had 60 Hz humMost had 60 Hz hum

Hum problem resolved, Hum problem resolved, QST,QST, May, 1998 May, 1998 Binocular matching transformers Binocular matching transformers

replace autotransformers ~ 2001replace autotransformers ~ 2001 Commercial versions begin ~ 2001Commercial versions begin ~ 2001

AYL-4R contains grounding & layout issuesAYL-4R contains grounding & layout issues

A K9AY Loop BenefitsA K9AY Loop Benefits Significant SNR improvement over TX Significant SNR improvement over TX

antennas on 160 & 80antennas on 160 & 80 Okay on 40, useful from 300 KHz to 30MHz Okay on 40, useful from 300 KHz to 30MHz

if you home-brewif you home-brew Steerable null (QRN, QRM, Local Noise)Steerable null (QRN, QRM, Local Noise)

Front lobe VERY broadFront lobe VERY broad Best LF receive performance for the sizeBest LF receive performance for the size

11 λλ Beverage = 550 feet Beverage = 550 feet K9AY = 30 ft long, 25 ft high, single K9AY = 30 ft long, 25 ft high, single

supportsupport

Elevation Pattern - High Elevation Pattern - High Angle NullAngle Null

Azimuth Pattern – Typical Azimuth Pattern – Typical CardioidCardioid

At elevation = 61 Degrees

K9AY – Basic RF DesignK9AY – Basic RF Design

Rg - Ground Impedance - Unavoidable

Rterm9:1 XFMR

CAREFUL Design to minimize inter-winding capacitive coupling

Receives from XFMR end

Directional K9AY LoopDirectional K9AY Loop

Small Size

Termination and feed at the same location

Typical InstallationTypical Installation

Typical Stand-Alone Typical Stand-Alone InstallationInstallation(N4GG’s is in the woods – Tree (N4GG’s is in the woods – Tree limb support)limb support)

Gain, F/B, RDFGain, F/B, RDF

Do I need to understand this Do I need to understand this stuff? stuff? No - Just put one upNo - Just put one up

Very Short Course Follows…….Very Short Course Follows…….

Forward GainForward Gain

Not importantNot important Required Gain:Required Gain:

Enough to overcome common mode Enough to overcome common mode spurious signal incursion and spurious signal incursion and preamp noise floorpreamp noise floor

After that – who cares?After that – who cares? K9AY: -23 dBi @ 1.8 MHzK9AY: -23 dBi @ 1.8 MHz 11λλ Beverage: -11 dBi @ 1.8 MHz Beverage: -11 dBi @ 1.8 MHz

Front-To-BackFront-To-Back

Useful for improving SNR by Useful for improving SNR by applying a null to:applying a null to: QRNQRN QRMQRM Local NoiseLocal Noise

RDF (Receiving Directivity RDF (Receiving Directivity Factor)Factor)

Figure of merit for comparing Figure of merit for comparing receiving antennasreceiving antennas

RDF = Forward gain minus RDF = Forward gain minus hemispherical average gainhemispherical average gain

General idea: General idea: If we are skywave noise limited, then the If we are skywave noise limited, then the

more sky we can null, while we have our more sky we can null, while we have our antenna pointed at the signal, the better antenna pointed at the signal, the better off we are.off we are.

Said differently, less sky = better SNRSaid differently, less sky = better SNR

This is important

3D Antenna Pattern – Single 3D Antenna Pattern – Single VerticalVertical

Source: ON4UN’s Low Band DXing

Typical Transmit Vertical

3D Antenna Pattern3D Antenna Pattern2 Vertical Array Fed in 2 Vertical Array Fed in

QuadratureQuadrature

Source: ON4UN’s Low Band DXing

Similar to K9AY

Performance ComparisonPerformance Comparison@ 1.825 MHz in dB@ 1.825 MHz in dB

AntennaAntenna RDFRDF F/BF/B

Vertical OmniVertical Omni 5.0 0 5.0 0

½ ½ λλ Beverage 6.5 Beverage 6.5 30 @ 18°30 @ 18°

EWE, Flag, Pen’t 7.0 – 7.4EWE, Flag, Pen’t 7.0 – 7.4 Varies Varies widelywidely

K9AY 7.5 – 7.7 K9AY 7.5 – 7.7 28 @ 28 @ 60°60°

1 1 λλ Beverage 10.1 Beverage 10.1 29 @ 18°29 @ 18°Source: N4GG

Demo* – K9AY LoopDemo* – K9AY LoopAt N4GGAt N4GG

*DVD Demo in separate file

Array Solutions AYL-4R Array Solutions AYL-4R

OutsideOutside

NEMA Style NEMA Style PLASTICPLASTIC Box – Lowe’s Box – Lowe’s 4 ft Ground rod or better – Lowe’s, R. 4 ft Ground rod or better – Lowe’s, R.

ShackShack Transformer, termination resistor, SO-Transformer, termination resistor, SO-

239239 For two directions – DPDT Relay and For two directions – DPDT Relay and

85 ft wire loop85 ft wire loop For four directions – two relays & two For four directions – two relays & two

loopsloops Handy tree or Handy tree or non-metallicnon-metallic support support

AYL-4R or Home BrewAYL-4R or Home Brew

AYL-4R or Home BrewAYL-4R or Home Brew

K9AY’s Original Home-K9AY’s Original Home-BrewBrew

N4GG’s Home-BrewN4GG’s Home-BrewLooks Awful – Works Great

Ferrite beads on coax

Ferrite beads on control cable

Occasional Maintenance Occasional Maintenance IssueIssue

Original QST DesignOriginal QST Design

Autotransformer and three grounds tied together introduce common mode signals & noise, AC relay current through the autotransformer introduces

hum

DON’T BUILD THIS!

Constructed ProperlyConstructed ProperlySource: ON4UN LB DXing

AYL-4R Single Ground AYL-4R Single Ground ApproachApproach

AYL-4R Questionable Grounding

AYL-4R Outdoor UnitAYL-4R Outdoor Unit

Terminating R & RelaysNEMA Enclosure

Direction Switching RelaysMatching Transformer

Looks Nice! Grounding not optimum..

Ground loop

Suggested AYL-4R ModsSuggested AYL-4R Mods

Drill a hole herefor control lines

Use this as a drain hole only

Break the ground loopper the instructionmanual

Add ferrite beadsTo break the controlline ground loop

InsideInside

Enclosure, LEDs, Switch, DiodesEnclosure, LEDs, Switch, Diodes Receiver protectorReceiver protector

Antenna can deliver big signals Antenna can deliver big signals – lightening, transmit capture– lightening, transmit capture

Preamp (maybe)Preamp (maybe) Bandpass filter (maybe)Bandpass filter (maybe)

N4GG Home-Brew N4GG Home-Brew Control BoxControl Box

N4GG Home-Brew N4GG Home-Brew Control BoxControl Box

Receiver Protection

RF Path @ N4GGRF Path @ N4GG

To Receiver

InsideOutside

Preamp(Optional)

Limiter(Optional)

BPF(Optional)

Suggestions Only

W3LPL

DXE RPA-1Or W7IUY

ICE 196

What’s ImportantWhat’s Important

Non-conductive support (tree limb Non-conductive support (tree limb is fine)is fine)

Max distance from vertical antennas Max distance from vertical antennas and from resonant antennasand from resonant antennas

Isolated signal return and antenna Isolated signal return and antenna groundsgrounds Control line ground might need Control line ground might need

isolation as wellisolation as well Some form of receiver protectionSome form of receiver protection

What’s UnimportantWhat’s Unimportant

Ground/Ground rod qualityGround/Ground rod quality Loop shapeLoop shape RadialsRadials

Not needed in GeorgiaNot needed in Georgia Can ruin antenna patternCan ruin antenna pattern

Variable Termination ResistanceVariable Termination Resistance Vactrols have multiple problems Vactrols have multiple problems Helps F/B, nil effect on RDFHelps F/B, nil effect on RDF

Impedance ratio = turns ratio squared

Typical Impedance Matching TransformerBinocular – 77 material

Winding the matching Winding the matching transformertransformer

Primary: 4 Turns – Goes On SecondSecondary: 12 Turns – Goes on First - Matches 50 ohms (10 turns for 75 ohms)

Transformer Transformer MeasurementsMeasurements

Flat from 1.7 to 30 MHzFlat from 1.7 to 30 MHzTest R=470 ohms

Tips & TricksTips & Tricks Outdoor unit needs a drain holeOutdoor unit needs a drain hole Isolate the signal return ground (coax Isolate the signal return ground (coax

shield)shield) Buried transmission line may helpBuried transmission line may help

MUST have bury-rated coaxMUST have bury-rated coax Solder ground wire to ground rod with a Solder ground wire to ground rod with a

torch before installationtorch before installation Test matching XFMR before use (home-Test matching XFMR before use (home-

brew)brew) Run the common mode and TX Run the common mode and TX

interaction tests (home-brew or ALY-4R)interaction tests (home-brew or ALY-4R)

Okay its up – Now What?Okay its up – Now What?

Testing!Testing! Listen to AM BC Band in daytimeListen to AM BC Band in daytime

F/B should be terrificF/B should be terrific Listen on 160 and 80 – A LOT!Listen on 160 and 80 – A LOT!

Should be able to null signals and QRNShould be able to null signals and QRN

Common Mode Test – Next SlideCommon Mode Test – Next Slide TX Antenna Interference Test – TX Antenna Interference Test –

Next SlideNext Slide

Key Test # 1 - Common Key Test # 1 - Common ModeModeTest for signal & noise incursionTest for signal & noise incursion

Disconnect loop wires, find strongest Disconnect loop wires, find strongest BC band signal and measureBC band signal and measure

Connect antenna wires and measure Connect antenna wires and measure delta signaldelta signal

N4GG’s measures 40 dBN4GG’s measures 40 dB Home Brew, Isolated Grounds, BeadsHome Brew, Isolated Grounds, Beads

K1ZZI’s measures ~40 dBK1ZZI’s measures ~40 dB AYL-4R, Isolated Grounds, No BeadsAYL-4R, Isolated Grounds, No Beads

K4DLI’s measured ~15 dB until connecting K4DLI’s measured ~15 dB until connecting relay ground to antenna ground, then > 40 relay ground to antenna ground, then > 40 dBdB

Some Grounding experiments may be necessary for optimization

Key Test #2 – TX Antenna Key Test #2 – TX Antenna DetuningDetuning Find a test signal on 160 meters Find a test signal on 160 meters

and carefully measureand carefully measure Connect 160 TX antenna to an Connect 160 TX antenna to an

antenna tunerantenna tuner Run tuner through all possible Run tuner through all possible

settingsetting TX antenna should not affect F/BTX antenna should not affect F/B

Make or Buy?Make or Buy?

AYL-4RAYL-4R $259$259 May require ground May require ground

mods, ferrite beads mods, ferrite beads and rewiring for best and rewiring for best performanceperformance

Includes Preamp and Includes Preamp and BPFBPF Sometimes usefulSometimes useful Sometimes in the waySometimes in the way

Preamp BP: 1.5 – 4 MHzPreamp BP: 1.5 – 4 MHz

Looks Nice – Saves Looks Nice – Saves TimeTime

Home BrewHome Brew Parts ~ $50Parts ~ $50 DXE Preamp $109DXE Preamp $109 ICE Limiter $39ICE Limiter $39 No ground issuesNo ground issues Satisfaction with a Satisfaction with a

job well-donejob well-done Operating Operating

FlexibilityFlexibility 300 KHz – 30 MHz300 KHz – 30 MHz

Summary – K9AY Rx Summary – K9AY Rx AntennaAntennaGood performance in a small space Good performance in a small space

for low costfor low cost

Broadband: 300 KHz to 30 MHzBroadband: 300 KHz to 30 MHz

Optimum for 160M and 80MOptimum for 160M and 80M

Easy to Build, Erect, OperateEasy to Build, Erect, Operate

- Try one! - - Try one! -

Additional MaterialAdditional Material

Performance vs. Performance vs. Termination R Termination R

@ 1.825 MHz AND @ @ 1.825 MHz AND @ Rg=100ΩRg=100Ω RR (Ω) (Ω) RDFRDF (dB) (dB) F/BF/B (dB) (dB)

340 7.65 17 @ 45° 368 7.66 20 @ 48° 397 7.65 22 @ 50° 434 7.64 27 @ 52° 476 7.61 39 @ 54° 530 7.55 31 @ 57°

594 7.47 23 @ 59°

~ +/- 1%

Elevation Pattern vs. R, Elevation Pattern vs. R, Rg=0Rg=0

Which is better ???????

RDF=7.41

RDF=7.51

Elevation Pattern vs. RElevation Pattern vs. RTermTerm, , Rg=0Rg=0

Two 100 ft radials one inch above the ground that are in-line with a loop willdestroy its performance

Nearby resonant structures will degrade performanceCan be cured through detuning those objects

Termination “R” in the Termination “R” in the AYL-4RAYL-4RResistor(s)Resistor(s) R in OhmsR in Ohms680 only 6804700 װ 680 5942400 װ 680 5302400 װ 4700 װ 680 4761200 װ 680 4341200 װ 4700 װ 680 3971200 װ 2400 װ 680 368All 340