Low Band DX / Contest Receiving Antennas Using End-Fire Arrays of K9AY
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Low Band DX / Contest Receiving Antennas Using End-Fire Arrays of K9AY Loops Richard C. Jaeger, K4IQJ Auburn, AL Huntsville, August 20, 2011 PowerPoint PPT Presentation


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Low Band DX / Contest Receiving Antennas Using End-Fire Arrays of K9AY Loops Richard C. Jaeger, K4IQJ Auburn, AL Huntsville, August 20, 2011 [email protected] OUTLINE. Introduction & Overview K9AY Array Simulation Results Array Implementation 3 Element 2 Element Results

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Low Band DX / Contest Receiving Antennas Using End-Fire Arrays of K9AY Loops Richard C. Jaeger, K4IQJ Auburn, AL Huntsville, August 20, 2011

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Low band dx

Low Band DX / Contest Receiving Antennas Using End-Fire Arrays of K9AY Loops

Richard C. Jaeger, K4IQJ

Auburn, AL

Huntsville, August 20, 2011

[email protected]


Outline

OUTLINE

  • Introduction & Overview

  • K9AY Array Simulation Results

  • Array Implementation

    • 3 Element

    • 2 Element

  • Results

  • Discussion / Observations

© RCJ - 2


Background low band receiving

BACKGROUNDLow Band Receiving

  • Started with K9AY loop pair

  • Added 4-square of short verticals (100’ side)

  • Very poor ground conditions

    • Very rocky with rock shelves and clay

    • 2-3 mS/M ground conductivity

    • 4-Square not level

  • K9AY loop pair generally better than 4-square

© RCJ - 3


Background

BACKGROUND

  • Wanted to try a 4-square of loops

    • Could not site the 4-square array well on my lot

    • Uneven lot + esthetic considerations

  • Reviewed some existing literature

    • K9AY paper on loop arrays [1]

    • ON4UN book [2]

    • Dallas Lankford Papers [3]

  • Realized that the side elements of the 4-square essentially operate in parallel

  • Decided to try a 1-2-1 binomial array of loops

  • Design goal - maximize RDF

© RCJ - 4


Background 4 square end fire transformation

4-Square Array End-Fire Array

1/0

Incoming

Signal

1/0

2/q

1/q

1/q

1/2q

1/2q

BACKGROUND4-SQUARE / END-FIRE “TRANSFORMATION”

© RCJ - 5


Rdf receiving directivity factor

RDFReceiving Directivity Factor

  • Noise generally comes in from all directions

  • RDF compares main lobe gain to average gain over whole antenna

  • RDFdB = Gfor(dB) - Gavg(dB)

© RCJ - 6


Array comparison k9ay loop

ARRAY COMPARISONK9AY Loop

Forward Gain: -23.6 dBi

Average Gain: -31.0

RDF: 7.4 dB

Horizontal Beamwidth: 173o

F/B: 9.5 dB

© RCJ - 7


Array comparison two element endfire array 80 spacing

ARRAY COMPARISONTwo-Element Endfire Array - 80’ Spacing

Gain: -25.6 dBi

RDF:10.5 dB

Horizontal Beamwidth: 96o

F/B: 16.0 dB

© RCJ - 8


Array comparison three element endfire array 80 spacing

ARRAY COMPARISONThree-Element Endfire Array - 80’ Spacing

Gain: -29.2 dBi

RDF:12.7 dB

Horizontal Beamwidth: 75o

F/B: 24.0 dB

© RCJ - 9


Array comparison four element endfire array 80 spacing

ARRAY COMPARISONFour-Element Endfire Array - 80’ Spacing

Gain: -37.2 dBi RDF: 14.4 dB Beamwidth: 54o F/B: 24.4 dB

(1:2.65:2.65:1)

© RCJ - 10


Array comparison vertical patterns vs number of elements

ARRAY COMPARISONVertical Patterns vs. Number of Elements

1

2

3

4

© RCJ - 11


Array comparison horizontal patterns vs number of elements

ARRAY COMPARISONHorizontal Patterns vs. Number of Elements

1

2

4

3

© RCJ - 12


Array comparison three element array 160m 80m

ARRAY COMPARISONThree-element Array - 160M & 80M

1.825 MHz

3.505 MHz

© RCJ - 13


Array implementation placement of the arrays

ARRAY IMPLEMENTATIONPlacement of the Arrays

  • Layout of NE/SW (160’) & NW/SE (115’) Arrays

  • Heavily wooded lot

  • Front yard is left of house

  • Small lake off to the right

  • Downhill slope to right

© RCJ - 14


3 element array optimization alternate current ratios

3-ELEMENT ARRAY OPTIMIZATIONAlternate Current Ratios

Design point

1:1.8:1

3 Current Ratios

1:1.9:1

1:2:1

© RCJ - 15


3 element array optimization alternate current ratios1

3-ELEMENT ARRAY OPTIMIZATIONAlternate Current Ratios

  • Enhanced RDF achieved with other current ratios

  • Settled upon 1:1.8:1

© RCJ - 16


Array implementation system design

ARRAY IMPLEMENTATIONSystem Design

  • Controllers

    • One Hi-Z

    • One DX Engineering

  • Hi-Z Amplifiers

    • 500  antennas connected directly to amplifier inputs

    • Center amplifier drives a coax pair & two controller inputs

    • Output Resistance Rout

      • 75 W for ends

      • ≈ 38 W for center - adjusted for 1.8:1 output

  • Must switch loop termination with controller phasing

  • Beaded chokes (The Wireman)

    • 50  coax

© RCJ - 17


Array implementation miscellaneous

ARRAY IMPLEMENTATIONMiscellaneous

  • Make Loops as identical as possible

  • 3-ft ground stake under antenna

  • Four 20’ radials under each loop (45o relative to loop)

  • Beaded chokes throughout

    • Approximately 1000  on TB

  • “Braid breakers” now in

    NE/SW array

    • No apparent difference

  • No observed interaction with grounded aluminum supports

    • Simulation shows small effect

    • Plan to use as short vertical array

Feedline Choke

© RCJ - 18


Array implementation phasing lines

ARRAY IMPLEMENTATIONPhasing Lines

  • Network or antenna analyzer

  • Adjust by measuring the resonant frequency of open-circuited coax lines

© RCJ - 19


Array implementation loop termination and switching

ARRAY IMPLEMENTATIONLoop Termination and Switching

Single Termination with

DPDT Switch

Doubly Terminated with

SPDT Switch

© RCJ - 20


Array implementation loop antennas supports

ARRAY IMPLEMENTATIONLoop Antennas & Supports

“Hidden” in Front & Side Yards - Black Wire & String

Fiberglass (NE/SW) or Aluminum Poles (NW/SE)

© RCJ - 21


Array implementation amplifier switching boxes

ARRAY IMPLEMENTATIONAmplifier/Switching Boxes

Single Loop Corner Loop Pair

© RCJ - 22


Array implementation amplifier switching boxes1

ARRAY IMPLEMENTATIONAmplifier/Switching Boxes

  • Weather-Proof Boxes (Lowes)

    • Hi-Z Amplifier: should be ac coupled

    • Direction Relay

    • Termination Resistor

    • Stainless Steel HW

© RCJ - 23


Results experimental setup

RESULTSExperimental Setup

  • Array Solutions VNA 2180 (50 W)

  • Port A drives 50 W coax with 50-W termination at input of High-Z amplifiers

  • 75 W coax from controller to VNA

  • 75 W - 50 W Pad at input to VNA Port B

  • Measurements repeatable to within 0.3 dB and less than 0.5o

© RCJ - 24


Results measurements

RESULTSMeasurements

Note: Same phasing line utilized on 160 & 80 M

Gain in good agreement with SPICE models

© RCJ - 25


Results final simulations 160 m

RESULTSFinal Simulations - 160 M

© RCJ - 26


Results final simulations 80 m

RESULTSFinal Simulations - 80 M

© RCJ - 27


Results final simulation comparisons

RESULTSFinal Simulation Comparisons

© RCJ - 28


Results dx the bottom line

RESULTSDX - The Bottom Line

  • Copied FR/DJ7RJ & 5R8RJ night after night on 160

    • Not readable on inverted L transmit antenna

  • Worked S79GM on both 160 M & 80 M.

    • Also could not copy on inverted L

  • PJ4 - First TB qso required loop array

  • Missed 9Q5ØQN - couldn’t hear me

    • Consolation – Easily heard and worked on 80 M for new one

  • Past season successes

    • TJ9PF, 4L/UUØJM, XU7ACY, 9L5MS, 5M2TT, BU2AQ

    • 234 Countries, 38 Zones

  • 160M propagation testing with VK3ZL

    • 13 times through June-July-August QRN in 2010

    • 33 times so far June-July-August 2011

  • Routinely use on 160 M / 80 M to “save ears”

  • Use on any frequency where there is an advantage

    • E.g. 40M, 30M and up - there are lobes pointed somewhere

    • Have used on 17M and 12M

© RCJ - 29


Results contesting the bottom line

RESULTSContesting - The Bottom Line

  • Low Band DX Contests

    • Can now hear well on 160/80 M

    • Operation far less difficult / tiring on the low bands

    • 2 EL K9AY Loop Array with Half Size Loops

      • Worked fine on 80M

      • Marginal output on 160M

  • Recent NAQP CW

    • Much grumbling after the contest regarding qrn problems on 80/160

    • I really had little trouble hearing on 80 or 160

    • Biggest problem was selecting the correct direction

© RCJ - 30


Two element array design implementation

TWO-ELEMENT ARRAYDesign & Implementation

  • Simple Implementation

  • Two-element Arrays Give Very a Useful Improvement (3 dB)

  • RDF: 7.5 dB  10.5 dB

  • Narrow Spacing Possible if Space is Limited (30+ feet)

  • Half Size Loops

    • Work well on 80/40/30

    • Marginal so far on 160M

  • Elements Were Originally Added One at a Time

  • Significant Improvement Noted at Each Step

© RCJ - 31


Two element array implementation

TWO-ELEMENT ARRAYImplementation

  • Hi-Z Amplifiers

  • Hi-Z 2-3 Element Controller

  • 4 Loops for 4 directions

  • 13o Phasing Line

© RCJ - 32


Two element array phase plots for two antenna paths

TWO-ELEMENT ARRAYPhase Plots for Two Antenna Paths

Hi-Z Amplifiers

Hi-Z 2-3 Element

Controller

150 ft RG-6 Coax

13o Phasing Line

RCJ - 33


Two element array vna 2180 results

TWO-ELEMENT ARRAYVNA 2180 Results

© RCJ - 34


Two element array final simulation using measured data

TWO-ELEMENT ARRAYFinal Simulation Using Measured Data

Gain: -28.6 dBi RDF: 10.4 dB Horiz. Beamwidth: 98o

© RCJ - 35


Discussion observations loops and short verticals

DISCUSSION / OBSERVATIONSLoops and Short Verticals

  • A short vertical array parallels NE/SW array

    • Separated by approximately 20’

  • Loops almost always better at my location

    • Vertical array better only one time in two months of comparisons

  • Simulation indicates small advantage for the loops

    • Array factor should be the same

    • Inherent F/B of loop provides some advantage (1+ dB)

  • Output of wider spaced array is clearly higher

  • Vertical supports on NW/SE array can operate as short (26’) vertical array elements

    • Plan to be able to switch back and forth - not implemented yet

  • My skill level is much higher now than when I did first 4-square installation - phasing not optimal

© RCJ - 36


Discussion observations other ideas

DISCUSSION / OBSERVATIONSOther Ideas

  • Latest version

    • Doubly terminated loops

    • Switch single amplifier input; Should ac couple loops to amplifiers

  • An alternative for three-element array ratios

    • Use identical amplifiers & attenuate the front and rear amplifiers by a factor of 0.54.

    • Only requires one coax from the center amplifier

    • Noise figure is degraded by attenuation factor

    • Degradation was noticeable when I tried it

  • Side rejection is very high.

    • One array may be useful as “noise” antenna for the other.

  • Combine the two array outputs, to fill 45o directions

    • RDF drops to 10 dB

© RCJ - 37


References

REFERENCES

  • Gary Breed, K9AY, "Arrays of K9AY Loops: "Medium-sized" low band RX antenna solutions," Sept. 15, 2007. http://www.aytechnologies.com

  • John Devoldere, ON4UN's Low-Band DXing, Fourth & Fifth Editions, ARRL, Newington, CT: 2005 & 2011.

  • Dallas Lankford, http://groups.yahoo.com/group/thedallasfiles

  • http://www.fcc.gov/mb/audio/m3/index.html

  • Hi-Z Antennas 4-Square, http://www.hizantennas.com

  • DX Engineering 4-Square, http://www.dxengineering.com

  • Max-Gain Systems, http://www.mgs4u.com

  • The Wireman, http://www.thewireman.com

  • Richard C. Jaeger, K4IQJ “Multi-Element End-fire Arrays of K9AY Loops,” expanded version of 2011 Dayton presentation, May 15, 2011, available from the author. ( [email protected] )

© RCJ - 38


Low band dx

  • THANK YOU FOR YOUR ATTENTION

  • QUESTIONS?

[email protected]

© RCJ - 39


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