--------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00006 Date: 12/22/97 From: ROB DENNIS Time: 08:08pm \/To: ALL (Read 0 times) Subj: Field Day Part 1 Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). SUBJECT: Field Day Antennas & Equipment. Part one This is an eight part series and will conclude in April so that anyone building these antennas or preparing for Field Day will have enough time. FIELD DAY OVERVIEW: There are many stories from field day events that new amateurs hear from rain,wind,and rotten luck to the day the team made the top 10% in the class. Field day is not a contest but it is hard to tell with some clubs or groups. For point chasers,total HF QRP CW will bring in the big points. Of course, excellent antennas are a must to make the QRP CW work in a sea of Amateurs. There so many combos of point gathering that it could make your head spin. One year I made a full size 40m 2ele beam and under poor conditions we acked up over 800 points on SSB alone at 100w. CW pulled in another 600 which was over 40% of our total score. We had the E.F.Hutton station on 40m. When our station talked everyone listened. BTW,it took two people to move he beam to a new bearing. :) Field Day is actually an event to see just how well amateurs can put together an emergency communications field station and make as many contacts as possible in a twenty-four hour period. Huricane Andrew taught us the value of Field Day here in Florida. So when you get out to participate in Field Day, think of what it would be like to have no commercial power,little or no water,food,cover,and help. It's just you and your ham friends providing the only local communications link to the rest of the USA. When disaster happens know one knows the date in advance. So keep these designs and ideas and prepare now. Keep them in a kit that you can grab in a moments notice. When disaster strikes, you're ready! As for the Field Day event,all you'll have to do is show up with your kit. ========================================= NOTE: All of the following in this series is based on no commercial power or facilities. If these are available to you,treat them as a plus. ========================================= EQUIPMENT Transceivers o 2m (144-148){All mode & FM} [Mobiles,HTs] o PACKET with laptop & software o Simplex operation o HTs for local comm at the site o Satellite work o HF (80/75m, 40m, 20m, 15m, 10m) [DC powered rigs] *CB mobiles for the real McCoy-Not everyone is a ham when disaster happens. o Hi VHF and UHF for SAT work or simplex Receivers o Scanners for local emergency reception o AM/FM Commercial band (540-1610 kHz,88-108 MHz) o DC powered Television. Gen HF o Tuners o SWR bridge Power o Batteries - deep cycle 12Vdc (trolling motor type or the type used in golf carts) o Solar Cells for recharging batteries o Small generators ( don't forget the fuel ) o Battery chargers to operator off the generators o Power supplies to operate off the generators o Wind generators (pray for a good wind which usually comes with the rain) o Large generator (if possible) Supports o Crank-up towers o Push-up masts o Sling shot and/or bow and arrow,fishing line (There maybe a tree or pole handy) o Tower sections (Like Rohn 20/25) Coax (stick with coax for this event unless you have a clear shot to the ig) o Jumpers o RF runs (that actually reach the antenna without moving the rig. Misc o Safety Belt o Rain coat o First Aid kit o Water o Packaged,ready-to-eat food o Gum o A hat and bandana (sun and sweat) or prepare for cold weather for the real McCoy. o Toilet paper (sometimes lots of it because no one else remembers) o Pencil,notebook,and calculator(solar powered,when does a battery go ad?) o Extention cords o Soldering iron and solder o Toolbag with the right tools this time :) o Extra connectors (PL259 males,bullets,barrels,elbows,BNCs etc,etc.) o Mosquito repellent (SLAP!! "Oh!,sorry Bob." A must!) o Asprin or equal (For the 5 a.m. headache) o Imodium D for the green-apple two step from too much coffee by 10 a.m. Sunday o Coffee (I forgot) and accompanying equipment. o Plop-plop,fizz-fizz if you have a headache and upset stomach from the rain,wind,and rotten propagation,not to mention the two day old pizza you're still nawing on. uhhhhhh. "Field Day,Field Day from...from ... What the hell is he call we're using this year? And someone check Bob. He hasn't made a contact since I slapped that mosquito on his forehead!" Next: Some antennas and a kit you can make. -WS --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4) --------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00007 Date: 12/22/97 From: ROB DENNIS Time: 08:08pm \/To: ALL (Read 0 times) Subj: Field Day Part 2 Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). Antennas and Field Day kits. Antennas: A wide range of antennas have been used for field day from simple wire antennas to full sized yagis. I'll list the different types of HF antennas I have seen,used and set-up, rating them on portability, set-up,performance,survivability,multi-band,and overall average. portability: How easy can the antenna be transported by vehicle and/or hand-carried to the site. set-up: Once at the site, how easy is the antenna to set-up and tune. performance: Does the antenna punch through the crowd and hear well? Does the antenna need a tuner? survivability: How does it hold up to the weather. Does the SWR change when it gets wet? Can it take a crash and be set right back up again? Can it handle a strong lighning storm with high gusty winds and rain? multi-band use: How well does the antenna work on more than two bands with or without a tuner? Overall average: total of each area divided by five. Scale is 1 to 5 with 5 being the best. ANTENNA PORT. SU PERF. SUR MBU OAA =================================================================== Whip 4 4 2 5 1 3.2 Groundplane 3 3 2 4 1 2.6 Bigstick 3 5 3 5 1 3.4 A-99 5 5 3 5 1 3.8 Hustler vert 3 1 3 4 4 3.0 R5 & R7 3 2 3 4 5 3.4Cs Vert Dipole 3 3 3 4 2 3.0E Inv.Vee 5 5 3 4 2 3.8E Slopers 5 5 3 4 2 3.8E Wire Dipole 5 4 3 4 2 3.6E Wire Loops 5 3 3 3 2 3.2 Cubical Quad 3 3 5 2 2 3.0Cm Yagi 3 2 5 3 2 3.0Cm LPDA 2 1 5 3 5 3.2Cs Recommendation code: E:Emergency antenna for the real thing Cs:Single Rig Antenna (1A, 1B, 1C Stations) Cm:Multi-Rig Antenna (Stations operating more than one rig) The recommendation codes are there for you to use as a guide rather than aw. You can use E antennas on field day and most do. If you are a point chaser, the Cs and Cm antennas will do the job better but require more work. Cs are designed for the single station in mind,one antenna,one rig,1 to 4 operators,multi-band output. Cm antennas are designed for the ulti-rig,multi- antenna,multi-everything station with multi-band output. Kits: Kits can come in a wide range of flavors. But just what is a kit? A kit is a prepared package constisting of at least the following: o An antenna that can be assembled and installed in under 30 minutes. o Coax with connectors at least 50-ft in length that can handle at least 100w continuous. o A small tool pouch including spare connectors and adaptors. o A small first aid kit. o A flashlight with spare batteries. o A cheap rain poncho. o A 3-ft coax jumper. o An inexpensive but fairly accurate SWR/PWR meter. o Three #2 pencils and small note book. o 50-ft extension cord. o Rope or cord to hang the antenna. o Cheap plastic tarp. o A low wattage 12Vdc lamp. All this should be in a bag or perferably in a foot locker to go. The footlocker can double as a table and also leaves room for your rig,mic,a 12Vdc deep cycle battery and small power supply. There is always the possibility that you will be located near a command center which will probably have a generator. Or there maybe a generator near you which will allow you to plug in the power supply,place the battery etween the rig and the power supply incase you loose power during a communication. It will act as an UPS. Run the minimum power needed to make the contact to conserve your power. Kits can be larger and have many more antennas. You can setup kits for emergency use and/or field day. A four inch diameter PVC pipe,10 feet long with screw on caps can serve to hold a pushup mast and beam antenna. This can also hold two supports. Where there is no cover for a station,the PVC pipe and supports can be set up with a tarp covering them as such: ========================================== PVC pipe /==========================================\ / || || \ / || || \ / || || \ guys / || || \ / || || \ / || || \ || || support \ Handles can be placed on the PVC pipe for easy carrying. Designs are endless and I'll continue on next time with some antenna mods for quick set-up and use next time. -WS --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4) --------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00008 Date: 12/22/97 From: ROB DENNIS Time: 08:09pm \/To: ALL (Read 0 times) Subj: Field Day Part 3A Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). Field Day Antennas & Kits - part 3 Quick set-up modifications for antennas: One of biggest problems during an emergency or field day operations is the assembly and tuning of an antenna. Granted,a whip does not require much in he line of tuning or assembly,however a yagi would. As I recommended before,use antennas that are prepared prior to an emergency or a field day and for emergency use; the simpler the better. Things to keep in mind are that stations outside the emergency area are running at their ull potential with large directional antennas and full power. Trying to match them while operating in a mud & debris enviroment,out of the back of a car,may be a large undertaking,not practical under the situation. You may have walk in serveral miles carrying 80-lbs of equipment and upplies to reach the emergency site. As for field day, it's much easier. Preps can be made months in advance and it's this one factor that can make or break a field day. ============================================================ Lets look at the Yagi,Cubical Quad,Inverted Vee,and Wire Dipole. These antennas seem to appear at most field days stations I've been to and I've been to several. Keep in mind that a sloper will have similar olutions, which is another antenna I've seen at field day sites. YAGI: (3 Element mono band,HF,armstrong rotor,gamma match) {Use the Cushcraft as a model} Assemble at home per directions. Assemble coax to be used at field day and e sure to provide enough (ie 70-100 ft). Test the coax via a dummy load with 00 watts of power CW. Check the SWR and loss at the desired band for the coax. When complete,save for antenna testing. Place the assembled antenna on a mast or tower for tuning. This height should be the height the antenna is to be used at during field day. I would recommend here that,if possible,test the antenna at the site ith the support that is to be used during field day. Adjust the element lengths and gamma match,with the coax tested before,until all the 'kinks' are worked out. The SWR should be less than 1.5:1 across the band area you desire to operate in. Remove the antenna intact and mark joint fittings of the tapered elements. Mark the dogbone on both the DE and the gamma match element. Disassemble the antenna and store in a PVC 4-in pipe with caps or a wooden box or canvas bag. Coil the coax and cap the PL-259s. Disassemble the mast or tower. Bag the hardware and attach to the support. When Field day or an emergency comes up, you are ready with premarked and pretested equipment. I have done this for 6 years and have found that it aves a bunch of grief. Use the coax you tested,not some hoser's botch job. And do your own assembly. If it fails,there is no one but you to blame. This concept can take a 2000 point total to a 4000 point level if done ight. In an emergency situation,it's the difference between a poor signal and a clear signal. Make it so the tuner is not required. Continued next posting................ :) --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4) --------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00009 Date: 12/22/97 From: ROB DENNIS Time: 08:09pm \/To: ALL (Read 0 times) Subj: Field Day Part 3B Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). Continued from previous posting: part 3 Cubical Quads: (Mono band,armstrong rotor,etc) This antenna can be a real hoser if not constructed correctly the first ime. Preps on this antenna are a must. Spreaders must be checked and elements lso checked. There is nothing worse than getting to the field day site and having difficulty with a Cubical quad. A strong antenna but a real pain in the butt raising and lowering to adjust,especially in the rain. Like a box kite,this antenna does lend itself to the wind. Whether you use the D/DE or DE/R configuration,it makes no difference. This is a homebrew antenna for the most part. There is very little in the commercial source market for these antennas. So,get your sh** together early if you want to use a Cubical quad on field day. Assemble per your design and test per the yagi directions. Cumbersome as it is,this must be done. Mark all connection points and if possible,use expanding spreaders and wire clamps on the ends. -IF- you use a tuning arm,be sure it's protected in the correct position and can be easily re-adjusted if required. A cubical quad can fold down into a very neat package,but that will take some forethought on your part. ================================================== Inverted Vees: (fixed,mast support or improvise) An Inverted Vee *may* tune fine at home and then be out to lunch at the ield day site. Using the tuning extentions I posted for Inverted Vees will solve any problems relating to this. Why this happens is that at home the IVee is interacting with Guy wires or other wire antennas or something in the immediate area of the antenna. At my home,the roof flashing does not require a tuner when used as an ntenna on 40m,I found this out by accident. Thus,my 40m inverted V was very ifficult to tune. So was a 15m yagi I had once. Solution: I grounded the roof flashing. Select a clear open area to cut,assemble and test the antenna. Once this is accomplished,the IVee should work just fine. Hints: Raise and lower the antenna using a rope and pulley. You can attach a rope & pulley to the mast prior to raising and securing the support. Use rope as guys rather than cable. A wheel & tire from a car make an excellent mast base when combined with a clamp & flange assembly. This appeared in QST I believe about a couple of years ago. Any good mast base will work and I have used plywood and a hinged base support many times. If you can,use a 1:1 BALUN. Hook ups are easier and so is raising. ================================================= Wire Dipoles: (fixed,mast or rope support) Pretty much like the Inverted Vee,prepare ahead. Similar problems may happen so test in an open area. At the site,determine where the antenna needs to face and then pick out the best supports. If using masts,set up similar to a large volley ball net (very large). The farther apart the supports,the more the rope will sag if no enter support is used. On 10m and 15m this is not too much of a problem. By the time you get to 40m and below,the sagging is a big problem. I will suggest the wire dipole be supported in the middle and the ends held out with rope. Set up similar to the Inverted Vee. Use a 1:1 BALUN. ================================================== -WS --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4) --------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00010 Date: 12/22/97 From: ROB DENNIS Time: 08:10pm \/To: ALL (Read 0 times) Subj: Field Day Part 4 Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). Field Day Antennas and Kits: Part 4 Setup at a site can be easy or a nightmare. I'm sure even a simple wire dipole has had it's day in the sun beating the amateurs 14 to 0. Scope out your site first and note structures,cover,water,toilets,etc. Take a friend and make extensive notes. Draw a layout of the site and if possible,measure the distances where you plan to put your antennas and equipment. Here's an example: This site is at a park by a river. 1X tree 1[pavillion] 1T picnic table [toilets] 2X tree 3X tree 4X tree 2[pavillion] 5X tree 6X tree 2T picnic table <- North ========================================================== ========================================================== river Location state: New York Looking at this site it can be seen that most of the contacts are going to e west and south although some contacts will be east and north. Your geographic location plays a big factor in you antenna placement. This same site in Central Florida will have a different lay-out. And the same site in Washington State will be different again. Look at the setup and make some notes on how you would setup the following antennas and equipment: 10m two element yagi 15m two element yagi 20m aluminum dipole 40m Inverted Vee 80m Wire dipole SAT setup PACKET setup Generators (2) Food area Public greeting area You have three push-up masts and each coax is 70 feet for HF and 30 feet for VHF/SAT. The distance between the pavillions is 75 feet. Here's another site: 1X tree [building] W water tower L street light 2X tree [building] 3X tree North ---> Location: Kansas Use the same antennas as above except 40m is a wire dipole. 2X and 3X are 120 feet apart. -WS --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4) --------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00011 Date: 12/22/97 From: ROB DENNIS Time: 08:10pm \/To: ALL (Read 0 times) Subj: Field Day Part 5 Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). Field day antennas and kits : part 5 Rotor use on field day: Somehow,rotors have been deemed off-limits in some unsaid word by amateurs during field day operations. This is nothing more than pure BS. If you have a beam antenna then get that rotor under the beam and use it,especially if you are running 'A' for field day. If you believe an amp or two draw on a generator for 30 secs is going to uin your power source,well...what can I say. Even in an emergency condition,it is not necessary to run a wire antenna and have a car battery as a source of power every time. But that may be all you have. Rotors work and they work well. Pre-preps include quick disconnects on your control cables,lubrication of the bearings,U-bolt de-corrosion and ubrication ,pre-testing as a MUST before using a rotor on field day or in emergency use. Rotors can be stored in storage boxes made of wood or old luggage. SOME NOTES: o Do not over rate your rotor. - Light duty means light duty. Don't stack a 10m and 20m beam on a rotor built for a TV antenna. o Do tin the wires before attaching them to rotor and/or controller. - Frayed wires are shorts waiting to happen. o Do not attach the control wires with the control box powered. o Do disconnect via the QD connector when lightning storms are in the area. (MOLEX Style quick disonnects) - Power down the rotor and use the QD. It's the one item we seem to forget in a lightning storm. -WS --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4) --------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00012 Date: 12/22/97 From: ROB DENNIS Time: 08:11pm \/To: ALL (Read 0 times) Subj: Field Day Part 6 Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). Subject: Field day Antennas and Kits - part 6 Kits: (Weather boxes for rigs) Keeping in mind the kit boxes of a previous post,a box can be made to house your rig,P/S,tuner,and speaker. For example,an old machinary crate box can be used for this purpose. The box should be about 2' X 1.5' ant the top and at least 1.5' deep with a lid. The box can be cleaned out,sanded,and stained or for that rustic look, Placing handles on the sides makes for an easy lift. The lid can be hinged and a clasp placed on the front for locking. Feed through RF connectors can e installed on the back side for antenna attachment. A fan or pair of fans on eith side can be added for cooling. External power connectors round off the field day / emergency kit. The radio kit could look something like this: _________________________________________________________ | | | | | SPEAKER PAIR VHF rig | | | | | | |<--Fan | | Flow | MIC HOLDER | | | | HF Rig | | | | FAN SWITCH | |_______________________________________________________| leg leg Screw on legs can be added to the box if a table is not available. Also the lid can be removed and legs attached for a seat. -WS --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4) --------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00013 Date: 12/22/97 From: ROB DENNIS Time: 08:11pm \/To: ALL (Read 0 times) Subj: Field Day Part 7 Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). Subject: Field day, push-up masts and tower sections More times than not we end up running our field day operations from places that are not quite the greatest locations for antennas. With this in mind the field day team must plan ahead by using the good ole push-up mast. They are easy to tote to the site and set-up. Another item is the Rohn tower section. Mounted to a piece of plywood with a mounting plate and guy lines to support the tower sections. A three section tower is easy to assemble and tilt up with just a few amateurs. Add a mast and an antenna and up it goes. Looking at the emergency aspect of operation,a tower maybe a bit tough to cart into a disaster area where the push-up mast would prove a better choice. The mast can be secured at the bottom using a spare tire and clamp/flange. Guying the mast is a must. The mast can be stored in a 4-in PVC pipe with screw on caps as discussed earlier. Handles can be attached for ease of carry. Another concept is the crank-up tower mounted to the bumper of a pick-up or van. The tower is slid back to the half way point and then tilted up. A step ladder allows the attachment of an antenna or used for tuning. Also this set-up allows the amateurs to attach the antenna before the tower is raised when using a whip,wire antenna,or aluminum dipole antenna. ********************************************************* I hope some of this postings have helped you with concepts used during field day and in emergency operations. See you this field day from Cape Canaveral Air Force Station operating as K4FD. -WS --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4) --------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00014 Date: 12/22/97 From: ROB DENNIS Time: 08:12pm \/To: ALL (Read 0 times) Subj: Gamma Match Mod Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). SUBJECT: Gamma modification for better symmetry & gain This subject has been discussed before on the HAM echo and will be further discussed here with more detail. Most gamma matching devices are mounted to the side of the driven element. This technique is good for matching,but does not provide good pattern. The symmetry of the antenna pattern is distorted to the side of the antenna that the gamma match is located on. Several antenna brands were tested with all brands tested showing the same result. The pattern produced by the side mounted gamma is kidney shaped. This shaping accounts for the fact that you can hear a signal on one side of the beam and not the other. The side to side ratio is not consistant. In the case of horizontal eams,the gamma hangs down,wasting gain and affording a loss of signal reception that could otherwise be used. What would it take to move this lost antenna gain and sensitivity into the area of the pattern that could be utilized? Not a whole lot in fact. The entire modification can be done in under a half an hour and for less han a dollar. What results is that the wasted gain to the side of a vertical beam is moved forward and the wasted gain under a horizontal beam is moved into he horizontal plane forward. The average gain increase is near 1.5 dB over the previous gain rating of the antenna. What this means is that if your antenna produces 10 dBi it will now produce 11.5 dbi. Your Cushcraft eleven element yagi rated at 13.2 dBi will now produce 14.7 dBi. 13 dB is equal to a gain of 20,16 dB is a gain of 40,so you can see the improvement. To accomplish this,you will need to remove the gamma match from the antenna. Remove the di-electric innards and replace with a piece of RG-8 foam di-electric about 3-in longer. Pivot the tuning arm 90 degrees so that it faces the first director. Insert the gamma back into the tuning arm. Now,solder to the center pin of the coax feed point. If your coax feed point is a threaded section,crimp or solder on the appropriate fitting,then tighten the nut. You will need to retune the antenna at this point. Fairly easy? The results are incredible. Increased gain,better symmetry,better side to side and front to back ratios. This modification has been used here for over a year. When I turn the beam o the side of a signal,the results blow away any commercial beam. My nine element yagi can keep up with the commercial eleven element ntennas. Try it out. I'm sure you will enjoy the change. -WS --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4) --------------- FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: EGS00015 Date: 12/22/97 From: ROB DENNIS Time: 08:13pm \/To: ALL (Read 0 times) Subj: Circular Polarity Part 1 Original article from: Wayne Sarosi Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo. THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST. ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S). SUBJECT: Circular Polarized Antenna - part one There has been a request for a series on 'CP' antennas. The term 'CP' eluded me at first as I was not familar with the abriviated designator for circular polarization. At work, we just use the entire words. I'm going to begin this ten part series with the basics. After researching CP designs with a few engineers and fellow hams,I found that they knew very little about the subject. I also found I didn't know uite as much as I thought I did about circular polarization. So starting at the begining will help all out. First, let's discuss the circular polarized wave. There seems to be conflicting standards used by the world of physics and the IEEE. I found this to be true in four reference manuals including the ARRL Antenna Handbook. At least it's stated right up front but biased according to which text you read. We will follow the IEEE/ARRL standard in the following series for obvious reasons. There are two types of circular polarization; right and left. All of us agree up to this point. According to the ARRL Antenna Handbook,the following statement: 'Polarization Sense is a critical factor, especially in EME work or if the satellite uses a circular polarized antenna. In physics,clockwise rotation of an approaching wave is called "right circular polarization," but the IEEE standard uses the term "clockwise circular polarization" for a receeding ave. Amateur terminology follows the IEEE standard, calling clockwise olarization for a receeding wave as right-hand.' Confused yet? I read it five times before it sunk in. Physics uses 'right', IEEE uses 'clockwise',the ARRL follows the IEEE and calls it 'right-hand'. Just remember the 'right-hand' or 'clockwise' is for a receeding wave or one that is going away from you. [You have one minute to flap your lips with your finger and read the above paragraphs again.] ;-) Ok,now we know a reference we can base "right-hand circular polarization" n. Now I have an experiment for you to try. Obtain a hard rubber ball from the kids or a neighbor's kid and try this: -drop the ball with a "right-hand polarization" spin and watch which way the ball spins as it bounces towards you. You'll find it will spin in the pposite direction [this works great with a super ball]. This is exactly what happens in EME work. The "right-hand circular olarized" signal returns in the opposite polarity. The same holds true for passing satellites using circular polarization. An approaching satellite's circular polarized wave will reverse as it asses. Another quote from the ARRL Antenna Handbook states that the circular polarized wave and a linear wave are mathmatically special cases of an elipical wave. When the magnitudes are the same and phase angles are 90 degrees in time,we have circular polarization. -WS --- GoldED 2.42.G1219 * Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4)