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REAL WORLD COMPARISON MEASUREMENTS Clare - VE3NPC QCWA Dinner Nov. 21, 2006. HELIX ANTENNAS. Early Helix – 2 x 10 Turns. 1989. 2 x 15 Turn 70 cm Helix . 1991 ?. AO-13 Antennas. About 1994. AO-40 Antennas. 2001. 13 and 23 cm Helix Arrays. 2003 .

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Real world comparison measurements clare ve3npc qcwa dinner nov 21 2006

REAL WORLD COMPARISON

MEASUREMENTS

Clare - VE3NPC

QCWA Dinner Nov. 21, 2006

HELIX ANTENNAS




Ao 13 antennas
AO-13 Antennas

About 1994




So how did we do
So How Did We Do?

  • Only worked AO-40 in mode L/S

  • 6 other low orbiters were used by others

  • Used Yaesu FT-736R with 10 watts on L

  • There were 30 submissions

  • We made 102 QSO’s, nearly all on SSB

  • Placed 7th.


Ve3npc l s qso s ao 40
VE3NPC L/S QSO’s AO-40

  • AO-40 on mode L/S from 16 Sept 01 to 28 Jan 04

  • 10 watts output into 4 x 27 T helix array on the L uplink

  • Works out to about 1500 watts ERP

  • In that time I logged 832 QSO’s in mode L/S


More helix antenna operation
More Helix Antenna Operation

  • First satellite QSO in 1988

  • Now 18 years later have over 11 K Satellite QSO’s in log

  • With exception of mode A and K used in early RS satellites all were made using home brew helix ants for 70cm up and down links and 23 cm uplinks


So what
So What !

  • I have learned a lot about building and operating helix antennas.

  • They have worked very well on the air in competition with commercial crossed yagis, loop yagis and dishes that most satellite operators were and are using.

  • What my paper is about is that according to some published antenna modeling theory they should not have worked as well as the have.


The helix antenna
THE HELIX ANTENNA

  • Invented by Dr. John D Kraus in 1947

  • He constructed large arrays of helix antennas for radio astronomy



Kraus
Kraus helical beam antenna is one of the simplest types of antenna it is possible to make”

  • Gain (db)=10log3.325n

  • Linear function

  • Double n (turns) - double gain – 3 db

  • Four times n – four times gain – 6 db


Kraus1
Kraus helical beam antenna is one of the simplest types of antenna it is possible to make”

  • Satellite Experimenters Handbook

    0.8 > C > 1.2 C = circumference in wavelengths

    12 < a > 14 a = pitch angle in degrees

    But used C = 1 wavelength and a =12.5 degrees


V e3npc
V E3NPC helical beam antenna is one of the simplest types of antenna it is possible to make”

  • C = 1 wavelength

  • pa = 12.5 degrees


Helix antenna computer modeling nec
Helix Antenna helical beam antenna is one of the simplest types of antenna it is possible to make” Computer Modeling (NEC)

  • 1990 ARRL UHF/Microwave Experiments Manual – Bob Atkins KA1GT

  • 1995 ARRL Antenna Compendium - Emerson

  • 2005 Proceedings of the Southeastern VHF Society – Cebik W4RNL


Nec design theory
NEC Design Theory helical beam antenna is one of the simplest types of antenna it is possible to make”

The NEC designs concluded that :

- for a given number of turns there was a

particular value of circumference and

pitch angle that would provide peak gain.

- as the number of turns was increased the

increase in gain soon leveled off.


Bob atkins
Bob Atkins helical beam antenna is one of the simplest types of antenna it is possible to make”


Emerson
Emerson helical beam antenna is one of the simplest types of antenna it is possible to make”


Cebik
Cebik helical beam antenna is one of the simplest types of antenna it is possible to make”


Cebik1
Cebik helical beam antenna is one of the simplest types of antenna it is possible to make”


Emerson length
Emerson - Length helical beam antenna is one of the simplest types of antenna it is possible to make”


Consequences
Consequences helical beam antenna is one of the simplest types of antenna it is possible to make”

  • NEC modeling peak gain designs used in ARRL publications

  • Web page helix antenna calculators use NEC peak gain design formula

  • AMSAT “experts” come up with peak gain formula dimensions


Ve3npc 1990 or so
VE3NPC 1990 or so helical beam antenna is one of the simplest types of antenna it is possible to make”

  • Constructed several 70cm helix antennas following Bob Atkins design in the ARRL UHF/Microwave Experimenters Manual

  • They did not give any better performance.

  • Narrower band width and harder to get good feed match


Ve3npc 1992 93
VE3NPC – 1992/93 helical beam antenna is one of the simplest types of antenna it is possible to make”

  • Constructed several different 2.4 GHz helix antennas and arrays for AO-13

    mode S

  • All were over 30 turns and most used Bob Atkins peak gain design

  • Didn’t work – never even heard beacon

  • Made 4 ft dish – worked like a charm


Summer 2005
Summer 2005 helical beam antenna is one of the simplest types of antenna it is possible to make”

  • Dave VE3KL proposed constructing a 70cm helix antenna using the Emerson design

  • From my previous experience I questioned his choice

  • Dave was skeptical.

  • Well that started the ball rolling

  • Maybe I was wrong but I didn’t think so

  • Simple matter to compare his with mine

  • What appeared to be simple turned into a major project

  • Constructed and compared 10 different helix antenna


Objectives
Objectives helical beam antenna is one of the simplest types of antenna it is possible to make”

  • 1 To compare the peak gain design verses the simple Kraus design.

  • 2 To test the validity of the difference in gain relative to the number of turns (length in wavelengths).

  • 3 To test the effects of different boom materials.


Test equipment set up
Test Equipment Set Up helical beam antenna is one of the simplest types of antenna it is possible to make”


Antenna test range
Antenna Test Range helical beam antenna is one of the simplest types of antenna it is possible to make”


Comparison Results Between Four Kraus Design Helix Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg.


Gain directivity
Gain & Directivity Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

  • An antenna may be very directive i.e. exhibit a narrow forward beam width but due to the configuration of the side lobes and/or degree of losses, provide higher or lower forward gain


Kraus 12 5 cm increased turns
Kraus 12.5 cm-Increased Turns Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

12 turns

6.5 turns

26 turns

52 turns


Increasing turns gain differences
Increasing Turns/Gain Differences Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg


Comparison results between kraus design and emerson design
Comparison Results Between Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg Kraus Design and Emerson Design


70 cm 10 turn kraus emerson
70 cm 10 Turn Kraus/Emerson Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

Kraus 10 turns

Emerson 10 turns


12 5 cm 2 88 w l kraus emerson
12.5 cm 2.88 w/l Kraus/Emerson Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

Emerson 12 turns

Kraus 13 turns


12 5 cm 5 75 w l kraus emerson
12.5 cm 5.75 w/l Kraus/Emerson Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

Kraus 26 turns

Emerson 24 turns


Kraus design different boom materials
Kraus Design – Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg Different Boom Materials


Conclusions
Conclusions Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

  • Casts serious doubt on NEC computer modeling of helix antennas

  • Ant based on modeling doesn’t give predicted peak gain

  • 30 Turn helix ants can be made that will give real gain. Useful gain with 52 turns.

  • Aluminum or PVC OK for boom


Other verification
Other Verification Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

  • Can find no other information on direct experimental evidence to verify the computer modeling results of helical antennas !


Questions ? ? ? Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg


Ve3npc 23cm array constructed by kb9ups
VE3NPC 23cm Array Constructed Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg by KB9UPS

VE3NPC

KB9UPS


Who cares
WHO CARES !! Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

  • Checked my satellite QSL cards

  • 40 % did not list type of ant

  • Of the 1267 cards listing type of antenna only 37 used a helix (3%)

  • Only 3 were in the US

  • One VK,FY and FP

  • The rest European (G3RUH pattern?)

  • 22 countries


G3ruh james miller
G3RUH – James Miller Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

  • 1993 published design for 16 turn 2401 MHz helix

  • C = 1.06 wavelengths

  • P.A. 12.5 degrees

  • 3.3 mm copper wire conductor

  • Boom 1 x 1 inch aluminum

  • Measured gain (sun noise) = 15.2 dbic

  • Kraus gain = 17.3 dbic


Central states vhf society antenna range tests 1995 2006
Central States VHF Society Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg Antenna Range Tests 1995-2006

  • 15 helix antennas for 70cm, 33cm,23cm and 13cm measured

  • 2 met the theoretical (VE3KSK) – G3RUH design

  • 5 within 1 – 3 db

  • 8 within 4 – 11 db

  • Where theoretical = Kraus gain minus 3 db


Southeastern vhf society antenna range tests 2006
Southeastern VHF Society Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg Antenna Range Tests 2006

  • 2 helix antennas tested at 2304 MHz

  • One 27 turn and one 16 turn.

  • Both about 1 db less than Kraus gain minus 3 db


Ao 40 orbit
AO-40 Orbit Antennas of Increasing length. C = 1 w/l P.A.= 12.5 deg

60 k kilometers


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