144 Mhz EME Basics
by
Tim Marek - NC7K




Moonbounce  or EME (Earth-Moon-Earth) is the Art of  contacting  fellow Amateurs using the Moon as a 
passive reflector.What is needed to work this mode? That's a loaded question! For some 48 5  
wavelength  yagis is still not enough! My goal here is to  help  you make informed decisions as how best 
to be proceed in constructing a EME station of your own. Lets starts at the beginning....

WHY EME?

Lets review the distances possible using the various propagation  modes 
at 144 Mhz..

Line of Sight - 0 to 50 miles depending on terrain
Direct Path - 50 to 100 Miles
Tropo enhancement - 100 to 600 Miles or more
Meteor Scatter - 500 to 1400 Miles for the typical MS station
Es - 500 to 3000 Miles during short and infrequent openings
EME - 0 to 14000 Miles

As  you can see EME offers the only chance of extreme 144 Mhz DX  on  a 
consistent  basis.  Without  it WAS and DXCC  would  be  impossible  to 
achieve on this frequency. 



Natural influences affecting EME Communications

There are many factors at work that determine whether a contact will be successful of not. 


Orbit (Perigee - Apogee)

The  Moon  orbits  the  Earth approximately once every  28  Days  in  a slightly  Elliptical orbit. At Perigee 
(The closest the Earth and  Moon ever  get to each other) the 144 Mhz path loss approaches 251.5 DB  
and at  Apogee the value reaches 253.5 DB. As frequency increases, so  does the path loss to overcome.


Faraday Rotation

As the signal passes through the Ionosphere it Rotates in polarity both on  the  way  up and the return 
bounce. The amount  and  speed  of  the rotation are always shifting. When using arrays of fixed polarity 
it is necessary to wait for the polarity to rotate into phase for reception.At  times  this  never  happens and 
you  are  effectively  locked  out, regardless  how large your stations array, due to the 20 DB  difference 
between Vertical and Horizontal Polarity. Attempting to contact another station  complicates  matters  as 
now the signal must  pass  through  2 different ionospheric areas before arriving at the antenna. 


Spatial Polarity  


First  proposed  by KL7WE and K9XY in 1984, This  theory  explains  why stations  are audible at one me 
and not another. Imagine you  are  on the  Moon  looking at North America. A station there  using 
Horizontal polarity  is pointed at you and his wavefront arrives  horizontal.  Now look  at the station in 
Europe using Horizontal polarity.  Compare  his Wavefront to that of the N. American and you will see 
they appear to be out  of phase. At times the two polarities are 90 Degrees out of  phase and  20 DB 
down from one another. That is too much for the average  EME station  to  overcome  so  no QSO takes  
place...  EXCEPT  for  Faraday Rotation, which can rotate the wavefront into the proper polarity and a 
contact  takes  place.  Without Faraday most  EME  contacts  would  not happen.  This effect is 
documented by K2GAL in great detail within  the proceedings of the 1991 Central States VHF 
Conference.


Libration Fading 

A random fading of signals received off the Moon, caused by the rocking motion  of the Moon and the 
signal wavefront bouncing off it's  jumbled surface, taking on the irregular shape itself. The distorted  
wavefront now  is full of peaks and nulls which sometimes add up in phase,  while on the average they 
give a Seven percent Pi R Squared reflectivity. For short periods the path loss can be reduced by as 
much as 6 to 10 DB.


Sky Noise

As  the  Moon travels in its orbit the surrounding Sky is  filled  with other stars and galaxies all of which 
emit radio frequency noise.  Some celestial bodies are noisier than others and any additional noise  adds 
up  as  so many DB of degradation to your system. Measured  in  degrees Kelvin  it  can  vary from 170 
or so to 3000+ degrees.  Myself  I  have worked  stations up to 500 degrees K but only the very large 
ones.  Our own Sun also creates noise and at times obscures the Moon as they  both appear  in  the 
same place in the sky. On 432 Mhz and  above  Celestial noise  poses less of a problem as degrees K 
goes down in proportion  to increase in frequency. 
 

Scintillation

As described by Ray Soifer - W2RS in "QRP EME on 144 Mhz" published  in the 1992 Central States 
VHF Conference proceedings...  "According to Lawrence, When a radio wave from a distant source  (e.g., 
The  Moon)  reaches the ionosphere, the phase surface of  the  wave  is distorted  by  irregular  patches 
of varying  refractive  index.  These patches  are  constantly moving, giving rise  to  interference  effects 
which,  in  turn, result in fading known  as  Amplitude  Scintillation. Lawrence compares this to the 
apparent twinkling of optical stars." Ray goes  on to describe how this effect can contribute up to 10db  
OF  Non reciprocal enhancement to a EME circuit.
 






 
Other Factors influencing EME communications


Doppler effect - 300 Cycles at Moonrise/set

At Moonrise, due to the Doppler effect between the Earth and Moon, Your echo's will appear 300 or so 
cycles higher in frequency at Moonrise. As the Moon traverses the sky to a point due south the Doppler  
approaches nil.  As the Moon sets your echo's will appear lower in frequency  till at Moonset they are now 
300 cycles less. This can pose a problem to the new  operator  who  answers a CQ where he is hearing  
the  station  not allowing  for Doppler. With the filters available today that can  place your signal outside 
his receiver bandpass and no QSO will take place.


Locating and Tracking the Moon - Computer prediction

Several methods exist to predict and track the Moon. The most basic  is    a  Astronomers  almanac 
which will give Rise and  Set  information  for    your  location.  That's  just the tip of  the  iceberg  in  
information  necessary  to  predict the best times to operate EME.  Needed  are  the  ability to predict its 
movement across the heavens, Noise level of the  nearby  Sky, round-trip Distance and expected signal  
degregation  over the path.                            

With  the advent of readily available and affordable personal  computer systems locating and tracking the 
Moon has become quite a easy thing to do. Many excellent shareware tracking programs are available 
from  many computer bulletin boards (BBS) around the world. Several commercial products written by 
EME operators are available as well. Dave - W5UN has  evolved his product "SKYMOON" to the point 
where it also  includes the current directory of EME operators throughout the world. Here is  a list of 
software package I know of and use...                           


SKYMOON by W5UN - Graphic display with accurate aiming data. Great  aid in predicting the best time 
to operate and set skeds.

REAL  TRAK  by W9IP - I have yet to see this package operate  but  hear wonderful  things  from those 
who use it. Mike  is  actively  providing support and uploading upgrades when they become available.

EME  by  VK3UM - One of the best packages shareware has to  offer.  His newest  release will drive a 
hardware package that operates  the  rotor directly leaving the operator free to chase the signals.

VHFPAK by WA1OUB - One of the older packages around but worth owning  a copy.  Not  only  will  it do 
 Moon  tracking  but  Meteor  predicting, Bearding/Distance  measurements  and  EME  circuit  analysis.  
Includes TRACKER by WA1JXN.

MOONV500 by K7CA - His newest shareware utility to printout predictions and aid in scheduling. Worth 
downloading.

SKED80 by N1BUG/AF9Y/W9HLY - The premier EME scheduling utility used by Lionel  -  VE7BQH, Net 
control for the 2M EME net.  All  schedule  made through  the  net are kept in this format. I can't describe  
how  handy this software is. Not only does it function as a database of skeds  but will  look  for skeds that 
conflict for any reason,  Predict  the  best times to run between two stations, common Moon window, etc. 
It includes a list of current EME stations and their capabilities. The database  of skeds is uploaded weekly 
to the EME BBS in N.C. at (704)284-4854. 

 Here is a sample screen from VK3UM's EME program.


   
    MOON LOCATION Winter Time   NC7K    RENO                39:30:0 N 
    UTC Sunday     9/ 4/1995  144 MHz   Beam Width 7.5    119:45:0 W 
    Moon  Sun 
    UTCLocal  AZ   EL   DEC   GHA  TK HM-HM  dB   AZ    EL 
   
   0000 0000111.7746.27 15.63 78.57 315  267-1.59255.6727.76
   0010 0010114.1348.00 15.61 80.99 315  256-1.59257.4925.89
   0020 0020116.6349.69 15.59 83.41 314  245-1.59259.2624.00
   0030 0030119.2751.35 15.57 85.83 314  233-1.59260.9922.10
   0040 0040122.0852.97 15.56 88.25 313  221-1.58262.6920.19
   0050 0050125.0854.53 15.54 90.67 313  208-1.58264.3618.27
   0100 0100128.2956.04 15.52 93.09 312  195-1.58266.0016.35
   0110 0110131.7157.48 15.50 95.51 312  182-1.58267.6314.43
   0120 0120135.3958.84 15.49 97.93 311  169-1.58269.2312.50
   0130 0130139.3260.10 15.47100.35 311  155-1.58270.8210.57
   0140 0140143.5361.27 15.45102.77 310  141-1.58272.41 8.65
   0150 0150148.0262.32 15.43105.19 310  127-1.58273.99 6.72
   0200 0200152.8063.24 15.42107.61 309  113-1.58275.56 4.80
   0210 0210157.8464.02 15.40110.03 309   98-1.57277.14 2.89
   0220 0220163.1264.63 15.38112.45 308   84-1.57278.72 0.98
   0230 0230168.6065.08 15.36114.87 308   69-1.57           
   
   [Space] Continue with Pause ... [S] Continuous Scroll ... [Esc] Menu


   ---------------------------------------------------------------------



Here is a example of the output from MOONV500.
   
  D=BONN         E=MADRID          G=LONDON      J=TOKYO        A=AUCKLAND,N.Z.
  P=WARSAW       S=STOLKHOLM       U=MOSCOW      V=MELBOURNE  

 SUNDAY APR/ 9 / 1995   LAT 39.5   LON 119.8  ANT -3DB  5 EL, 5 AZ  NC7K - RENO

TIME   M AZ  M EL  DEC  DIST   NL  NFL   WINDOW     S AZ    S EL  OFFSET   TANT
   0  111.7  46.9   16  2.0   1.3  0.5   PDGES      255.6   27.8  145.1     272
 100  128.3  56.6   16  2.0   1.2  0.5   DGES       266.0   16.4  143.4     267
 200  152.7  63.7   15  2.0   1.1  0.6   GA         275.5    4.9  136.1     262
 300  185.5  65.7   15  1.9   1.1  0.6   AJ           -       -     -       256
 400  216.0  61.6   15  1.9   1.0  0.6   AVJ          -       -     -       251
 500  237.2  53.3   15  2.0   0.9  0.6   AVJ          -       -     -       246
 600  251.8  43.1   15  2.0   0.8  0.6   AVJ          -       -     -       241
 700  262.8  32.1   15  2.0   0.7  0.6   AVJ          -       -     -       236
 800  272.3  20.8   15  2.0   0.7  0.6   AVJ          -       -     -       231
 900  281.1   9.6   15  2.0   3.7  0.3   AVJ          -       -     -       499
2100   75.9   3.6   13  1.9   0.4  0.7   UPDGES     206.5   55.5  140.6     214
2200   85.0  14.5   13  1.9   0.4  0.7   UPDGES     228.0   48.5  147.0     213
2300   94.3  25.7   13  1.9   3.3  0.3   UPDGES     243.8   38.9  150.0     459

PRESS ANY KEY TO CONTINUE

F1 END     F4 HOUR  F5 HELP  F6 RESTART  F7 MINUTES  F8 YEAR  F9 MONTH  F10 DAY



Overall Moon conditions - Dec, Perigee, Sky noise, Distance



The  best possible EME conditions occur when Perigee occurs at  maximum Declination  with  minimal  
Sky Noise during the  Evening  hours  on  a weekend  with lots of activity. Every 20 years the Moon is as 
close  to the  Earth as it ever gets. As the moon goes through its cycle Max  Dec and Perigee drift apart 
creating a situation where to operate you  must pick  the  lesser of 2 evils, Low Dec or High Sky Noise. 
Add  into  the equation Libration Fading, Atmospheric Absorption/Disturbances, Spatial Polarity, QRM, 
Power Line Noise, etc and its still amazes me EME  style contacts take place at all. 

But,  There  are those times when things click for no  one  reason  and signals  are SO LOUD you would 
swear AO-13 changed its bandpass.  March 23rd  1994 was one such night. Hank - K2GAL was so loud I 
could  remove the 100 cycle Audio filter and the 24 DB GAsFet only to still copy  him on the room 
speaker. For EME that's LOUD! 



Common Moon Window - Can both stations see a common Moon? 
    
In  order to work another station the Moon must be visible to  both  of you.  Sounds simple but in practice 
can be maddening. Now in  Mid  1995 Perigee  and  Low  Sky noise are  occurring  and  Negative  
Declination causing the Moon Window from North America to Europe to be cut in  half or  worse.  Spatial 
polarity becomes even more of a headache  when  the Moon  is  low on the horizon. Couple that with low  
antenna  elevations mean  increased  terrestrial noise to deal with. As  I  said...  Sounds simple.



Moonrise / Moonset - 6DB ground gain 

In  North America the best time to operate is at or near Moonrise  when the highest level of activity can be 
had. Europe by far has the highest concentration of EME capable stations in the World. Many are 8 yagis 
or more.  From Moonrise to +15 degrees elevation a single yagi under  good conditions  can hear and 
work many stations with only 100 Watts and  at least 12 DBD antenna gain. Myself I have worked 4 
station with a single antenna  off  the rising Moon. With the extra 6DB of Ground  Gain  that single yagi 
performs like four. 



Activity or Sked Weekend - Sleep deprivation

Sked  or  activity  weekends are determined by  analyzing  the  factors outlined  above and deciding 
which weekend would hold the best  chances for  successful  contacts.  If your going to work EME  your  
forced  to abandon  all  normal  sleep  patterns as  you  must  follow  the  Moons schedule.  As Heinlien 
wrote "The Moon Is A Harsh Mistress" Sometime  I wonder  if  he didn't operate EME. Sleep deprivation 
will make  you  do strange  things.  You will forget to do things like turn on the  KW  HV supply and call 
CQ for several hours before finding the mistake. I have no suggestions on how to deal with it except to 
say "get plenty of rest BEFORE and AFTER each sked weekend". 




Scheduling - Net, Newsletter, Internet, Phone, Mail

The  prime  source  for all EME info has to be the 2M EME  Net  run  by Lionel - VE7BQH each Saturday 
and Sunday Morning on 14.235 Mhz. Here is where most of the skeds are made and passed. Typically 
20 - 40 stations throughout North America check in. If you could add up the total  years of EME activity 
each station you would see that for several hours  each weekend  over  100 years of EME experience are 
there to draw  on.  From this group I have received nothing but encouragement and assistance  in every 
phase of my EME experience. Thanks guys!

Doug  - W2CRS is now the Editor and Publisher of the "VHF  EME  REPORT" which  used to be 
published by John - K0IFL. He brings many  new  ideas and great editorial style to our ranks. 

If your not "Surfin' the Net" you don't know what your missing!  One  of the best things to happen to VHF 
is the advent of the  Internet Listserver.  The  VHF Reflector is a fantastic source  of  information. 
Through  this medium I've met many EME operators throughout the  World. Those of you with Internet 
access can send a message with SUBSCRIBE  in the main body to 
VHF-REQUEST@W6YX.Stanford.Edu and you be place on  the list . Any message sent to 
VHF@W6YX.Stanford.Edu will be routed to  all subscribers. 

Bev - W4ZD maintains the 144 Mhz EME directory. Periodically he uploads a  updated  version  on to the 
EME BBS mentioned  earlier.  Here  is  a complete database from station capabilities to Name, address, 
and phone number. If your wish to operate EME on 144 Mhz downloading a copy is  a must.  With this 
information you can either call or write stations  for skeds.


Basic Station Requirements


Antenna - Your goal for a entry level EME station should be at least  4 3.2  Wavelength yagis with full 
azimuth and elevation  capability.  Many good  designs  are  available commercially with Mike -  K6MYC  
and  his company M2 offering probably the best VHF antennas on the market. 

Myself I prefer to build my own based on one of the current designs. By constructing them from scratch I 
can tailor the final array to suit  my needs. Two of the best out right now are by DJ9BV and K1FO. One 
the EME BBS you can find BASIC programs to help design the antenna to fit  your need.  To  verify the 
design I highly recommend YO by  K6STI.  YO  will model  any yagi antenna up to 50 odd elements and 
optimize  the  design based  on  parameters  you set. Any antenna you chose  from  these  two designs  
should  perform well. All feedline lengths should be  kept  as short  as  possible  and made from the best 
low  loss  heliax  you  can afford. Any loss in the feed system is added to the overall loss of the 
circuit. 


Receiver - A stable receiver/transceiver/Transverter is imperative. The best  combination  is  a quality HF 
transceiver coupled  to  a   decent Transverter.  This gives you best of both worlds, A quality  signal  on 
VHF  with  all the characteristics of a HF rig -  CW  filter,  bandpass tuning,  great IMD specs, and 
improved flexibility of  installation.  A low  Noise  Preamp with less then 1db Noise figure and 20  DB  gain 
 is necessary to hear those weak signals. The best location for it would be atop the tower with a 
sequencer to assure you would never transmit into it.  The  complexity of such a system keeps many  
from  attempting  the project  at  all. I run my preamp in the shack between the rig  and  PA with only 25 
Ft of 1/2" heliax to the power divider.


Transmitter  - As my friend Larry - NF7P is fond of saying, More  Power   to  the  Tower"! Obviously the 
more power the better but  what  is  the   minimum required to obtain consistent results. From what I can 
gather   so  far a station running around 800 Watts into 4 Antennas should  hear   his own echoes some 
of the time, depending on conditions. Many  designs exist for KW PAs at 144 Mhz. Some of the best 
designs have appeared  in QST  over  the  years,  DUBUS, the Eimac EME  notes,  and  the  various 
Handbooks.  Though not available in the US, the "VHF DX" book is  still available  direct  from Europe. 
Contact Alan - G3SEK  for  details.  My choice  is  based all on The Economics of Availability, I picked  up 
 a batch  of  4CX250Bs  and a 2 tube amp cheap. If I  had  my  choice  the 4CX1500B  design in the 
ARRL handbook appeals to me. Ten watts  in  for 1400 out has some advantages not to mention a 
cleaner signal than a 80W brick  driving  a 8877. Whatever you end up with make  sure  the  power 
supply  is up to transmitting for many hours on end,  well  ventilated, etc. 


EME BUDGET CALCULATOR

                                 
                                  144 MHz   
                                 

           
           TX PowerTX FeedRX RX FeedRX BWANT GainPath Loss S/N of
           OUTPUT W Loss  N/F Loss  in Hz in dBi (Perigee) Echo  
           
     Stn A   1500    0.5  0.9  0.5    100  21.8    251.5    5.94 
           
     Stn B    800    0.5  0.9  0.5    100  21.8    251.5    3.21 
           
                             Station A as received by Station B   5.94 
                            
                             Station B as received by Station A   3.21 
                            



To  overcome this loss a circuit needs a minimum total gain of  38  DBd between 2 stations each at the 
KW power level. If one station is larger than  the other, that station will end up doing most of the work.  
That is  why at Moonrise its possible using only 100W and a single  yagi  to work the Superstations like 
W5UN or K5GW (Each who have in excess of 30 yagis on 2M EME)         
                                               

A typical 2M EME station consists of 4 yagis at least 3 Wavelengths  in length fed in phase with a KW 
transmitter output and  preamp with  less than  1  DB of Noise Figure. Setup as above you should  hear  
your  own echo's part of the time.






The  next  pages are some technical details that should  help  you  get started. Lionel - VE7BQH is due 
credit for the following information. 



   VE7BQH,JANUARY 4,1993

1. BOOM CORRECTION FOR THROUGH THE BOOM INSULATED ELEMENTS ON 2 METERS.

   PROVEN ACCURATE FOR BOOM DIAMETERS SMALLER THAN .055 WAVELENGTHS.
   MEASUREMENTS BY DL6WU.FORMULA BY G3SEK.

   FORMULA: C = 12.5975B - 114.5B^2 
            C = CORRECTION FACTOR AS A FRACTION OF THE BOOM DIA.
            B = BOOM DIA IN WAVELENGTHS
            B^2 MEANS B SQUARED

   BOOM DIAMETER           CORRECTION               ADD

   0.750" OR 19.050MM        10.56%           .0792" OR 2.01MM
   0.875" OR 22.225MM        12.10%           .1058" 0R 2.69MM
   1.000" OR 25.400MM        13.66%           .1366" OR 3.47MM
   1.125  OR 28.575MM        15.12%           .1701" OR 4.32MM
   1.250" OR 31.750MM        16.54%           .2070  OR 5.25MM
   1.500" OR 38.100MM        19.21%           .2881" OR 7.31MM 
             20.000MM        11.04%                     2.21MM
             38.000MM        19.86%                     7.55MM


2. ELEMENT DIAMETER CORRECTION ON 2 METERS
   THE FOLLOWING ARE SOME AVERAGE ELEMENT DIAMETER CORRECTIONS FOR 2M TO SCALE
   AN ANTENNA FOR A DIFFERENT DIAMETER ELEMENT.IT IS NOT SO SIMPLE AS JUST 
   ADDING A SIMPLE LINEAR CORRECTION AS THE OVERALL TAPER CHANGES DEPENDING ON
   THE DIAMETER OF ELEMENT.AS A CONSEQUENCE THE CORRECTION VARIES FROM 
   REFLECTOR TO LAST DIRECTOR.EG:6.25MM TO 5MM DIAMETER CORRECTION ON A 10 EL
   DJ9BV ANTENNA IS 2 MM AT THE REFLECTOR AND 6.91MM AT DIRECTOR 8.THE ABOVE
   WAS CALCULATED USING THE YOC 5.0 SCALING FEATURE.  
      
   DIA.  6.35MM   5.00MM   4.76MM   4.00MM
   ADD   0.00MM   4.50MM   5.00MM   8.00MM 
   

3. CORRECTION FACTOR FOR CUSHCRAFT STYLE MOUNTED ELEMENTS

   CORRECTION FACTOR ON 2 METERS = .3125" OR 7.94MM


4. DL6WU STACKING FORMULA

   Dopt =   WAVELENGTH / 2 SIN (beamwidth/2)

   GOOD RESULTS CAN BE OBTAINED DOWN TO 90 PERCENT OF THE ABOVE FORMULA IF A
   SMALLER STACKING FRAME IS DESIRED.CLOSER STACKING THAN 90 PERCENT OF       
   DL6WU'S   FORMULA WILL RESULT IN A DEGRADATION OF G/T.
 







TYPE OF EME       SINGLE ANT.  OHMIC    ANT.     ARRAY       STATIONS & NOTES
ANTENNA           GAIN (dBd)   LOSSES   EFF.(%)  GAIN (dBd)

2 X K1FO 12 2.5   12.49        .07      98.5     15.39      W1XR
2 X F9FT 17EL     12.87        .09      97.9     15.77      SV1BTR
2 X 3219XB 3.14   13.29        .07      98.5     16.19      NT0V MOD CC 3219
2 X KLM 16LBX     14.13        .08      98.2     17.03      W2UHI
2 X CC 4218XL     14.15        .13      97.1     17.05      I1JTQ
2 X M2 5WL 4.85   14.74        .12      97.3     17.64      EA3DXU,HL9UH

4 X W1JR 8 MOD    11.15        .07      98.5     16.95      FIXED TO 144MHZ
4 X DJ9BV 1.8     11.25        .08      98.2     17.05
4 X CC 215WB      11.83        .08      98.2     17.63      K6AAW,KE7CX
4 X DJ9BV 2.1     11.88        .09      97.9     17.68      IW5CNS,IW2BNA
4 X K5GW 10 2.49  12.42        .11      97.5     18.22
4 X K1FO 12 2.5   12.49        .07      98.5     18.29      KJ7F,WA9KRT
4 X M285X 2.85    12.80        .06      98.7     18.60      VE7BQH 50 OHM
4 X CUEDEE 15LQD  12.86        .07      98.5     18.66      PA2CHR,HB9DBM,LA8K
4 X F9FT 17EL     12.87        .09      97.9     18.67      FR5DN
4 X CC 3219 3.14  12.88        .09      97.9     18.68      K4HWG,K2LME
4 X M285XX 2.85   13.00        .08      98.2     18.80      VE7BQH 20 OHM FEED
4 X DJ9BV 3.2     13.22        .09      97.9     19.02      NC7K,OZ9AAR
4 X 3219XB  3.14  13.29        .07      98.5     19.09      WA2GSX,W9QXP
4 X DJ9BV 3.6     13.67        .10      97.7     19.47      PE1DAB,LU7DZ,CX9BT
4 X K1FO 15 3.6   13.76        .07      98.5     19.56      OH5IY
4 x I2ODI 3.93    14.02        .07      98.5     19.82      I4XCC
4 X DJ9BV 4.0     14.03        .10      97.7     19.83      DL1GBF,9H1BT
4 X HG 215DX      14.09        .11      97.5     19.89
4 X KLM 16LBX     14.13        .08      98.2     19.93      KB0HH,W8WN,
4 x CC 4218XL     14.15        .13      97.1     19.95      SM5IOT,IK1FJI
4 X DJ9BV 4.4     14.31        .10      97.7     20.11
4 x CC 4219XL     14.42        .14      96.9     20.22      SM5MIX
4 X K1FO 17 4.4   14.44        .08      98.2     20.24
4 X KLM17LBX      14.50        .09      97.9     20.30      K1GVM,I1KTC
4 X CC 17B2       14.52        .09      97.9     20.32      VE1BVL,ON4GG
4 X DJ9BV 4.8     14.58        .10      97.7     20.38      F6IRF
4 X M2 5WL 4.85   14.74        .12      97.3     20.54      SM4RNA,KA5AIH
4 X KLM18LBX      14.80        .09      97.9     20.60
4 X K5GW 17 4.98  14.82        .15      96.7     20.62
4 X SM2CEW4A 4.92 14.83        .12      97.3     20.63
4 x EA3MM  4.92   14.90        .07      97.9     20.70      C3URA,EA3DXU/P
4 X M2 18XXX      14.97        .12      97.3     20.77      K0IFL,ZL1PE
4 X K1FO 19 5.2   15.01        .08      98.2     20.81
4 X KLM19LBX      15.03        .09      97.9     20.83      W7HAH
4 X SM5BSZ 4.95   15.27        .18      96.0     21.07      SM5BSZ SW POLARITY
4 X M2 19XXX      15.31        .12      97.3     21.11      N6OC
4 X KLM20LBX      15.33        .09      97.9     21.13
4 X AF9Y 22 6.0   15.74        .18      96.0     21.54
4 X K2GAL 21 EL   16.88        .19      95.8     22.68      EX K2GAL

6 X CUEDEE 15LQD  12.86        .07      98.5     20.36      SM0FUO
6 X CC 3219 3.14  12.88        .09      97.9     20.38      SM0PYP
6 X 32 EL COL.    13.90        .04      99.1     20.75      VE7BQH WINTER 91/2
6 X KLM16LBX      14.13        .08      98.2     21.63      SM2CEW,W0RWH
6 X CC 4218XL     14.15        .13      97.1     21.65      W0HP
6 X KLM17LBX      14.50        .09      97.9     22.00
6 X M2 5WL 4.85   14.74        .12      97.3     22.24      K6HXW,N7BNJ,LA2FGA
6 X SM2CEW4A 4.92 14.83        .12      97.3     22.33      NEW SM2CEW
6 X 18LBXXX       14.97        .12      97.3     22.47     
6 X AF9Y 22 6.0   15.74        .18      96.0     23.24      AF9Y POL ROT.

8 X CC DX120 COL. 12.05        .01      99.7     20.75
8 X KFGW 10 2.49  12.42        .11      97.5     21.12      WA6EIW
8 X K1FO 12 2.5   12.49        .07      98.5     21.19      C53GS,W7XU
8 X CC 3219 3.14  12.88        .09      97.9     21.58      K1MNS
8 x DJ9BV 3.2     13.22        .09      97.9     21.92      UZ2FWA
8 X DJ9BV 4.0     14.03        .10      97.7     22.73      DL3BWW,OK1MS
8 X 15XXLBF       14.10        .09      97.9     22.80      WA6MGZ
8 X KLM16LBX      14.13        .08      98.2     22.83      OH7PI
8 X CC 4218XL     14.15        .13      97.1     22.85      K7CA
8 X 4218XLD       14.26        .08      98.2     22.99      VE3BQN MOD 4218
8 X KLM17LBX      14.50        .09      97.9     23.20      VE1ASA
8 X M2 5WL 4.85   14.74        .12      97.3     23.44      LA8YB,EA6VQ,DL5MAE
8 x M2 19XXX      15.31        .12      97.3     24.01      AA4FQ,HB9CRQ
8 X KLM20LBX      15.33        .09      97.9     24.03
8 X AF9Y 22 6.0   15.74        .18      96.0     24.44
8 X K2GAL 21 EL   16.88        .19      95.8     25.58      K2GAL

12 X W1JR 8       11.15        .07      98.5     21.55      KL7X
12 X 28 EL COL.   13.23        .03      99.3     23.43      EX VE7BQH
12 X 32 EL COL.   13.90        .04      99.1     23.70      VE7BQH JULY 1992
12 X AF9Y 22 6.0  15.74        .18      96.0     26.14      AF9Y LOUDENBOOMER
16 X KLM17LBX     14.50        .09      97.9     26.10      WA1JXN
16 X M2 5WL 4.85  14.74        .12      97.3     26.34      DL8DAT,W4ZD
16 X KLM18LBX     14.80        .09      97.9     26.40      N5BLZ
16 X 18LBXXX      14.97        .12      97.3     26.57      I2FAK

24 X CC 214WB     11.83        .08      98.2     25.13      K1WHS
24 X M2 5WL 4.85  14.74        .12      97.3     28.04      WB5LBT
24 X KLM18LBX     14.80        .09      97.9     28.10      SM5FRH
24 X M2 19XXX     15.31        .12      97.3     28.61      KB8RQ
24 X KLM20LBX     15.33        .09      97.9     28.63      SM7BAE

32 X M2 5WL 4.85  14.74        .12      97.3     29.24      W5UN CURRENT ANT.

48 X K5GW 10 2.49 12.42        .11      97.5     28.62      K5GW
48 X M2 5WL 4.85  14.74        .12      97.3     30.94      W5UN OLD ANT.

Notes:
     1. All yagi antennas are assumed to use DL6WU stacking distances.
        Therefore, the stacking gain used is 2.9 dB.
     2. Many stations are using stacking distances considerably less than 
DL6WU.
        As a consequence, actual stacking gain is often in the 2.6 - 2.8 dB
        range.
     3. The collinear antennas are considerably understacked in the H plane.
        Therefore, the gain figures have been adjusted accordingly.
     4. No stacking harness losses are included in the gain figures.
     5. The program used to calculate the antenna gains etc was NEC for Yagis
        2.0. 20 segments per element were used for good accuracy.

                                               LIONEL H. EDWARDS
                                               VE7BQH
                                               ISSUE 12, June 12,1994
K1FO 27EL W/ 3/16" DIA ELE     
143.800 144.500 145.200 MHz
27 elements, millimeters
              4.7625 
    0.0000  516.5024 
              9.5250 
  312.1234  500.0000 
              4.7625 
  438.1687  487.1817 
  672.2606  476.0985 
  996.3831  467.3096 
 1398.5396  462.2139 
 1866.7209  457.0904 
 2394.9302  454.5045 
 2971.1506  451.9113 
 3589.3879  449.3118 
 4243.6450  446.7002 
 4927.9048  444.0694 
 5639.1797  441.4409 
 6368.4609  440.1216 
 7121.7549  438.7973 
 7890.0508  437.4722 
 8673.3584  436.1436 
 9469.8379  435.4797 
10266.3174  434.8149 
11069.7080  433.4900 
11882.0967  432.1551 
12703.4775  430.8148 
13527.8535  429.4750 
14361.2256  428.1329 
15187.7910  426.7884 
16014.3545  424.6669 
16840.9199  422.5548 

THIS YAGI WAS DESIGNED BY K1FO.
IT CAN BE USED IN ANY LENGTH
FROM K1FO11 TO K1FO27 OR HIGHER.

 GAIN AS K1FO23 = 15.90 DB                     .
 GAIN AS K1FO24 = 16.14 DB                     .
 GAIN AS K1FO25 = 16.35 DB                     .
 GAIN AS K1FO26 = 16.55 DB                     .
 GAIN AS K1FO27 = 16.73 DB                     .














dj9bv 6.43wl 21el
144.000   144.500   145.000
21 elements, millimeters
               4.0 
0000.0       513.5
               8.0
 360.0       489.0
               4.0
 525.0       473.5
 900.0       468.5
1350.0       463.5
1875.0       458.5
2460.0       456.0
3090.0       453.5
3750.0       451.0
4440.0       448.5
5160.0       446.0
5910.0       443.5
6690.0       441.0
7500.0       438.5
8340.0       436.0
9180.0       433.5
10020.0      431.0
10860.0      428.5
11700.0      426.0
12540.0      423.5  
13380.0      421.0

































I  realize  this  is  a brief overview  of  a  complicated  and  highly technical  subject.  In  offering  this I 
hope  to  have  stirred  your interest to pursue it further. I can't describe the feeling of  hearing your  own 
echoes for the first time, or your first EME QSO with 1  yagi and  100W with Dave - W5UN who made it 
seem so easy, or the first  time you  heard EME with the new array of 4 yagis. Its like being  a  Novice 
again and everyday holds something new. 




If  you have any comments or suggestions or a sked request please  send them to....




Tim.Marek@Megasystem.Com
or
Tim Marek, 360 Prestige Ct, Reno, NV 89506






                                                          73s     


                                                          Tim Marek           
                                                          NC7K 
                         





