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Weak Signal VHF by Tim Marek - K7XC
144 Mhz EME Basics

EME = Earth - Moon - Earth

EME 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 five 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

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 Internet.

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. In Mid 1995 Perigee and Low Sky noise were occurring with 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 internet. It 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 four 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 - K7MI 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. Available in the US from ARRL, the "VHF DX" book by Alan - G3SEK is a great resource of information. My choice of PA tube is based all on The Economics of Availability, I picked up a batch of 4CX250Bs and a 2 tube 2M amp for a song. 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.

To overcome the path loss of a EME circuit, a combined minimum total gain of 38 DBd between the 2 stations is needed along with each transmitting at the KW power level. If one station is larger than the other, that station will end up doing most of the work. That along with Ground Gain is why at Moonrise its possible to work the Superstations like W5UN or K5GW using only 100W and a single yagi.

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 and 20 DB gain. Setup as above you should consistantly be able to hear your own echo's under optimal conditions.

What follows next are some technical details from Lionel - VE7BQH that should help you get started.

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 K7XC,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


The following are YO ".YAG" files for the K1FO and DJ9BV antennas designs.

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 my own echoes for the first time, or my first EME QSO with 1 yagi and 100W with Dave - W5UN who made it seem so easy, or the first time I 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 please send click the "Contact Me" link above.

73s de Tim Marek - K7XC - DM09ol... sk

144 Mhz EME Basics By Tim Marek - K7XC