1. K9AY Loop Arrays for Low Band Contesting
Richard C. Jaeger, K4IQJ
May 16, 2013

2. INTRODUCTION K4IQJ Interests /Background Introduction
RDF Definition
Basic K9AY Loop Pair
K9AY Array Comparisons
2-3-4 Element Arrays
4 Element Array Design & Simulation
Array Implementation
Discussion / Observations
Dayton 2013
Dayton 2013

3. INTRODUCTION Interests Low Band Contesting DXing NAQP CW
ARRL & CQWW 160 Contests
Stew Perry
CW Sprints (Alabama Low Power Record)
DXing
Top of the Honor Roll, Need P5 on CW, CQ WAZ
300+ Countries Worked on 80 – 10
255 Countries Worked on 160M
Dayton 2013
Dayton 2013

4. INTRODUCTION Need to Hear Well on 160/80 M
Big Advantage in NAQP and DX Contests
Loops Seem Most Effective Receiving Antennas in My Locations (Poor Ground Conditions)
Discussed 2-Element Arrays
Presented 3-Element End-fire Array – 2011
Latest Effort - 4-Element Array (15.1dB RDF)
100 foot spacing (330’ total length)
RDF greater than individual beverages
Dayton 2013
Dayton 2013

5. BACKGROUND RDF: Receiving Directivity Factor
Design Goal Here: Maximize RDF
RDFdB = Gfor(dB) - Gavg(dB)
Noise generally comes from all directions
RDF compares the main antenna lobe gain to the average gain over the whole hemisphere of the antenna
Attributed to W8JI
Dayton 2013
Dayton 2013

6. BACKGROUND Reference Antenna - Short Vertical (20’)
RDFdB = Gfor(dB) - Gavg(dB)
RDFdB = 1.0 – (-3.9) = 4.9 dB
RDFdB = Gfor(dB) - Gavg(dB)
Dayton 2013
Dayton 2013

7. BACKGROUND Basic K9AY Loop
85’ Triangular Loop
25’ High, 30’ Wide
Resistive Termination
Directional Antenna
Easily switched in 2 directions
4 directions with an orthogonal pair of loops
9:1 Matching Transformer to Coax
Signal Arrival
RDFdB = Gfor(dB) - Gavg(dB)
RDF = (-24.7) - (-32.1) = 7.4 dB
Gary Breed, “The K9AY terminated loop – A compact, directional receiving antenna,” QST, vol. 81, no. 9, pp , September 1997.
Dayton 2013
Dayton 2013

8. LOOP ARRAYS Multi-Element Endfire Arrays
“Lossy” Antennas
Resistive termination
Little or no mutual coupling
Loops are Broadband – Usable over a Wide Frequency Range
Array Output Decreases as Number of Elements Increases
(-24 dBi)  (-40 dBi)
Luis, IV3PRK: “K9AY Loops Always Seem to Work”
Dayton 2013

9. TWO-ELEMENT END-FIRE ARRAY 80’ Spacing – 200o phasing
Two-Element Array
Equal amplitudes
Single phasing line
Rear element lags front element by > 180o
Gain: dBi
RDF: dB (+3 dB)
Beam Width: 96o
W/C F/B: 16.6 dB
Take Off Angle: 25o
Element 2 Phasing (-200o)
Dayton 2013
Dayton 2013

10. TWO-ELEMENT END-FIRE ARRAY Simulation Results - 160 M
RDF dB
Gain dBi
F/B dB
Note: RDF Falls as Gain Drops
RDF = 7.5 dB at 45o points
Dayton 2013
Dayton 2013

11. LOOP ARRAYS 3 & 4 Element Endfire Arrays
Binomial Endfire Array Nominal Amplitudes
3 EL (1-2-1)
4 EL ( )
RDF Optimization
(1-2-1)  ( )
( )  ( )
Dayton 2013

12. LOOP ARRAYS 3 & 4 Element Endfire Arrays
3 Element Array
80’ Spacing
Gain: dBi (20o)
Beamwidth: 66o
RDF: 12.5 dB
4 Element Array
100’ Spacing (Sensitivity)
Gain: dBi (16o)
Beamwidth: 49o
RDF: 15.1 dB
Dayton 2013

13. K9AY ARRAYS RDF Comparisons
( )  ( )
Dayton 2013

14. ARRAY IMPLEMENTATION Cross-Fire Feed (W8JI)
From Low Band DXing [3]
Dayton 2013
Dayton 2013

15. ARRAY IMPLEMENTATION 0o Hybrid CombinersZ
From Low Band DXing [3]
Dayton 2013

16. 4 EL ARRAY IMPLEMENTATION Amplifiergs & Coax Phasing Lines
Desired Gains (Hi-Z Plus-6 Amplifiers)
Elements 1 and 4: or dB
Adjust Output Resistance
Elements 2 and 3: or 0 dB
Output Resistance at 75 W
Desired Phase Delays on 160 M
Element 1: 0o
Element 2: 190o = 180o + 10o
Element 3: 380o = 360o + 20o  20o
Element 4: 570o = 540o + 30o  180o + 30o
Dayton 2013
Dayton 2013

17. 4 EL ARRAY IMPLEMENTATION Amplifier & Coax Phasing Lines
Desired Phase Delays on 160 M
Element 1: 0o
Element 2: 190o = 180o + 10o
Element 3: 380o = 360o + 20o  20o
Element 4: 570o = 540o + 30o  360o + 180o + 30o
Combiner: DX Engineering 4 Square Controller
Uses Three Separate Delay Lines
Two Inputs Go Through 180o Phase Inversion Transformer
Two Inputs Have 0o Shift Within the Controller
Antennas Reversed With External Switching
Dayton 2013
Dayton 2013

18. ARRAY IMPLEMENTATION Coax Phasing Lines
Network or Antenna Analyzer
Measure The Resonant Frequency Or Fault Of Open-circuited Line
Calculate Phase By Frequency Scaling
Dayton 2013
Dayton 2013

19. FOUR-ELEMENT ARRAY Simulation Results – 160 M
Spacing: 100 Ft
Amplitudes:
Crossfire Phasing: 0, -190o, -380o, -570o
Dayton 2013

20. FOUR-ELEMENT ARRAY Simulation Results (Cont.)
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21. FOUR-ELEMENT ARRAY Simulation Results - 80 M
Spacing: 100 Feet Between Loops
Amplitudes:
Crossfire Phasing: 0, -200o, -400o, -600o
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22. FOUR-ELEMENT ARRAY Simulation Results - 80 M
Dayton 2013

23. ARRAY IMPLEMENTATION Loop Termination and Switching
560 W Termination
DPDT Relay
Dayton 2013
Dayton 2013

24. ARRAY IMPLEMENTATION Loop Design and Array Control
Loops as Identical as Possible
High Impedance Amplifiers
(Hi-Z Plus 6)
ac Coupled (loop dc short)
Single 510-W Termination
Flooded RG-6 Coax
DPDT Relay Switching
A 3’ Ground Stake at Loop Center
Four 20’ Radials Under Each Loop (45o relative to loop)
Fiberglass Poles (MaxGain Systems)
Aluminum Can Also be Used
Loop Support, Direction Control Box, Hi-Z Amplifier
Hi-Z Amplifier Direction Control
Dayton 2013

25. 4 EL ARRAY IMPLEMENTATION Loop & Controller
Individual Loop Controller During Installation
Dayton 2013

26. 4 EL ARRAY IMPLEMENTATION Loop Alignment!
N/S Array E/W Array
Fiberglass Support Poles (Max-Gain Systems)
Control Cables and Coax in PVC on Ground
Array Looking NE Array Looking SW
Dayton 2013
Dayton 2013

27. ARRAY IMPLEMENTATION System Design
Combiner – Spare DXE 4 Square Controller
Hi-Z Plus 6 Amplifiers
500  antennas connected directly to amplifier inputs
Must Switch Loop Terminations with Controller Direction
Simple Switching of Inputs to Controller to Reverse Array
“Common-mode” Chokes (The Wireman)
Dayton 2013
Dayton 2013

28. ARRAY IMPLEMENTATION System Design
Delay 1
Delay 3
Delay 2
Dayton 2013

29. MULTIELEMENT ARRAY COMPARISONS
Verticals are Easier to Install
No Direction switching
Vertical Footprint Somewhat Smaller
Extra ft Needed for Loops
Loops Appear More Independent of Ground Conditions
Simulation Gives Loops a Slight Advantage in RDF ( dB)
Simulation Gives Verticals a Large Output Advantage (Not realized!)
Dayton 2013

30. K9AY LOOPS & SHORT VERTICALS Comparison of Simulation Results
Comparison - K9AY Loops (85’) and Verticals (26.5’)
# of Elements
RDF (dB)
Output (dBi)
Loops
Verticals 1
7.4
4.9
-23.6
5.8 2
10.5
9.8
-25.6 3
13.1
12.4
-29.2
7.9 4
15.1
14.7
-35.6
9.6
*Note: The actual output of the verticals is much lower when connected to high impedance amplifiers
Dayton 2013

31. K9AY LOOPS & SHORT VERTICALS Experiment Underway
Interlaced 3- Element Arrays
NE/SW Array
K9AY Loops and 26.5’ Verticals
Aluminum Loop Supports form
Vertical Array
Single Switch between Arrays
In Operation for 6 Months Through this Year’s 160 M Season
Dayton 2013

32. K9AY LOOPS & SHORT VERTICALS Qualitative Results Thus Far
Simulation
Aluminum Supports Do Not Disturb K9AY Loops
Loops Must be Floated to Avoid Vertical Array Pattern Distortion
Hearing of Both Arrays is Similar
Loop Array Almost Always has a Small but Perceptibly Better SNR (Ears can hear the 0.5 dB difference).
F/B of Loop Array is Better
Output of Loop Array is Actually Higher than that of Vertical Array
Dayton 2013

33. SUMMARY I Hear Well on the Low Bands The Arrays Act Similar to Yagis
Big Advantage in NAQP and DX Contests
The Arrays Act Similar to Yagis
Often Hear Signals Well that are Unreadable on My Transmit Verticals
Signals Pop Out of the Noise
Gain and F/B are Apparent
Unfortunately Not Rotatable
Frequently Usable on All Bands
(Although with Unknown Patterns)
Dayton 2013
Dayton 2013

34. REFERENCES
Gary Breed, “The K9AY terminated loop – A compact, directional receiving antenna,” QST, vol. 81, no. 9, pp , September 1997.
Gary Breed, K9AY, "Arrays of K9AY Loops: "Medium-sized" low band RX antenna solutions," Sept. 15,
John Devoldere, ON4UN's Low-Band DXing, Fourth & Fifth Editions, ARRL, Newington, CT: 2005 & 2011.
Dallas Lankford,
Hi-Z Antennas 4-Square,
DX Engineering 4-Square,
Max-Gain Systems,
The Wireman,
Richard C. Jaeger, K4IQJ “Multi-Element End-fire Arrays of K9AY Loops,” expanded version of 2011 Dayton presentation, May 15, 2011, available at Also 2012 Presentation on 2 Element Arrays.
Richard C. Jaeger, “Multi-Element End-fire Arrays of K9AY Loops,” QEX, pp , Jan./Feb
Dayton 2013
Dayton 2013

35. THANK YOU FOR YOUR ATTENTION QUESTIONS?
Dayton 2013
Dayton 2013