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Engineers!

Engineers!. What is Field Day. Field Day: is an Amateur Radio event is both a contest and an emergency preparedness exercise is 24 hour long with 37 hours setup time can be entered by individuals or groups can involve single or multiple amateur radio stations

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Engineers!

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  1. Engineers!

  2. What is Field Day

  3. Field Day: • is an Amateur Radio event • is both a contest and an emergency preparedness • exercise • is 24 hour long with 37 hours setup time • can be entered by individuals or groups • can involve single or multiple amateur radio stations • from within a 1000 ft. diameter circle • can use various modes of communication (SSB, CW, etc) • can use several power levels (under 5w, under 100w, • unlimited) • competitors must within the US or Canada & their • respective territories • is an excuse to party with people who share a hobby

  4. Basically Speaking: The idea is to contact as many amateur radio stations as possible within the contest period. Each contact consists of successfully transmitting and receiving a call sign, a number/letter category and one’s ARRL Section designation. • Scoring: • There is an elaborate scoring system • There are many ways to earn bonus points • Most points are earned per contact • The number of points per contact are awarded depend on • the mode, power level, and power source. • Winning: Two months after its over, winners are announced via QST Magazine, the official magazine of the ARRL.

  5. Setup Times: The contest begins Saturday 2pm EST, while setup begins 7pm Thursday EST. Covered by Setup Rules: All transmitters, receivers, antennas, feedlines, antenna tuners, tables, shelters, power sources, and supports for any of the above. Prohibited: Any equipment in place prior to the contest setup times that remains in place and is involved in Amateur Radio transmission. Not Covered by Setup Rules: Kitchens, bathrooms, contest logging equipment

  6. Our Club’s Choices: • Compete in the 5A category • Use less than 100 per transmitter • Use no more that 5 transmitters simultaneously • (NOTE: we get a 6th station free if UHF/VHF only) • Use power not provided by commercial mains. • Contest Goals: • Follow all contest rules, including setup time and the • 1000 ft. diameter rule • Put up an antenna system that will allow for the most • contacts in the shortest time, with the least effort. • Fit all stations within a 1000 ft. diameter circle.

  7. The Problems: Basically there are 6 amateur bands within the MF and HF bands that can be used by our 5 transmitters, 160 meters, 80 meters, 40 meters, 20 meters, 15 meters and 10 meters. Antenna Design: Because antennas have directional characteristics, we have make sure our antennas create usable signals where the most people live. We want the a strong signal per watt and low noise pickup on receive. Interference: Ham bands are on harmonic frequencies. Thus a 100 watt transmitter on 80 meters could produce interfering harmonics on 40, 20, 15 and 10 meters. We could cut back to 5 watts per transmitter, but then the ease of making contacts goes down.

  8. UHF-VHF: We are allowed to operate a single UHF/VHF station without affecting our 5A category. Thus we will only be able to use one UHF or VHF band at a time. To the right is a picture of the UHF/VHF antennas from last year. 6 meters = 50-54 MHz 2 meters = 144-148MHz 1 ¼ meters = 222-225 MHz 70 centimeters = 420-450 MHz-

  9. Self Interference The Elephant in the Room at Field Day

  10. Time: Our antennas must be erectable in relatively short order. We have roughly one day to put up what we need, including shelters and all the equipment that goes inside. Remember its hard to put up antennas in the dark.

  11. 2 Criminal Masterminds 4 ‘well trained’ Minions

  12. Sunspot Cycle: This year is a minimum year during the current 11 year sunspot cycle.

  13. 11 Year Minimum: And when there are fewer sunspots radio signals ‘bend’ less when they reach the ionosphere. This means that higher frequencies like the 21 MHz and 28 MHz bands (15 and 10 meters) will likely not bend enough in the ionosphere to return to earth inside the US and Canada, rendering them useless. Its this bending action that makes long distance communications on MF and HF frequencies possible.

  14. 160 Meter Issues: Meanwhile antennas for 1.8 MHz (160 meters) are so large that few Field Day contesters even try to use this band. Field Day 2018 May Be Limited: So this year’s event will rely mainly on three bands, 3.5-4.0 MHz (80 meters), 7.0-7.3 MHz (40 meters) and 14.00-14.35 MHz (20 meters).

  15. Talent: The Anne Arundel Radio Club has a spin-off group that uses 5 watts per station, and runs 100% Morse Code contacts. They have managed to siphon off a good percentage of the operators talented in Morse Code operation. This typically limits our club stations to using only 1 station operating Morse Code at a time. Thus at any given moment we typically have 2 stations on phone (voice), 2 stations on digital (PSK31 or RTTY), and 1 station on Morse Code. We do, however, make sure that one of our digital stations is equipped for Morse Code should operators become available.

  16. Ham Band Simple Facts: • 80 Meters: During previous Field Day’s we have made almost no contacts further west than the Mississippi River, and few daytime contacts. This band is excellent at night. • 40 Meters: During previous Field Day’s we have made contacts from across the US and Canada. This has been our most productive band as it is good both day and night. • 20 Meters: During previous Field Day’s we have made few contacts closer than several hundred miles. This band can be used both day and night, but typically for contacts along the gulf coast and in the far west. Contacts closer than the Mississippi River are much lower in number.

  17. Now knowing all this we have to plan an Antenna System

  18. Antenna System Goals: • Must focus on 80 meter, 40 meter and 20 meter operation • Must discourage interference between stations • Must fit within our budget!!! • Must be easily and quickly erected • Must fit in 1000 foot diameter circle • Must put a strong signal toward population centers • Must limit background noise pickup

  19. Where One Should Point the Strongest Signal: • A 20 meter antenna should point west or southwest • A 40 meter antenna should point mostly westward • An 80 meter antenna should point northeast/southwest

  20. And don’t forget our friend here! Self-Interference

  21. Discouraging Inter-station Interference • Wire Antennas like loops and dipoles in a straight line • produce the least interference because the lowest signal • levels are coming from the ends of the antennas. • Keeping antennas tuned for second harmonics at a • distance will also reduce interference. Thus an 80 meter • antenna should not be adjacent to a 40 meter antenna. • Also a 40 meter antenna adjacent to a 20 meter antenna • should be avoided and so on. Obviously at some times • these two rules may conflict. If so the lower frequency • antennas should receive the greater separation. This is • because in terms of wavelength they are closer together • when adjacent.

  22. Staying Within Our Budget: • Wire antennas are the cheapest to construct • They can be held up by masts (or the even cheaper trees) • Our club already owns 6 substantial 40 foot masts • These masts are easy to erect, bring down and store • Easy and Quickly Erected: In the past the Anne Arundel Radio Club has used towers and metal beam antennas for Field Day when available. Thought this worked extremely well, they are no longer at our disposal. The cost of same prohibits their use for this event. So our choice is limited to mast mounted wire antennas.

  23. 2 Criminal Masterminds 4 ‘well trained’ Minions

  24. Setting up a Mast: (aka What the Heck!)

  25. 1000 Foot Circle: In order to be able to run transmitters simultaneously on a single band, we needed 3 antennas for that band. So if we want to run 3 antennas for 80 meter, 3 for 40 meters and 3 for 20 meters we will need 9 antennas. But since there is little digital activity on 80 meters during Field Day (by custom) we can delete the 3rd 80 meter antenna bringing our total to 8 antennas Since we wanted our antenna array to be usable for years to come, when at least one antenna for 15 meters and/or 10 meters would be used, we add 2 more for 10 antennas total. So we needed to find out the approximate length of these 10 antennas end to end.

  26. The following dipole length’s were calculated using the formula 468 divided by the frequency in Mhz: • 80 meter phone = 123 feet 2 inches • 80 meter CW = 131 feet 10 inches • 40 meter phone = 64 feet 10 inches • 40 meter digital = 66 feet 1 inch • 40 meter CW = 66 feet 6 inches • 20 meter phone = 32 feet 10 inches • 20 meter digital = 33 feet 3 inches • 20 meter CW = 33 feet 4 inches • 15 meter phone/CW = 22 feet 1 inch • 10 meter phone/CW = 16 feet 7 inches • Total Length of All Antennas = 588 feet 6 inches

  27. DFRC

  28. 20 M Delta Loop 22 feet 22 feet Rope Rope 22 feet

  29. The following loop antenna lengths were calculated: • 80 meter quad phone = 102 feet 3 inches • 80 meter quad CW = 111 feet 7 inches • 40 meter delta phone = 54 feet across (42 feet 8 inches/side) • 40 meter quad digital = 41 feet 1 inch • 40 meter delta CW = 56 feet across (43 feet 5 inches/side) • 20 meter delta phone = 23 feet 6 inches • 20 meter delta digital = 23 feet 20 inches • 20 meter quad CW = 17 feet 11 inches • 15 meter delta phone/CW = 15 feet 10 inch • 10 meter delta phone/CW = 11 feet 10 inches • Total Length of All Antennas = 459 feet 3 inches

  30. DFRC

  31. Solution Found Our antenna line fits in the space allotted. Now we have to arrange the antennas along the line!

  32. Here is the Eventual Layout 40m Phone 15m Dual 20m Phone 40m Digital 20m CW 20m Digital 80m Phone 80m CW 40m CW 10m Dual In this grouping no two stations using a single mode or sharing a single band are adjacent to each other. This arrangement is about 2/3 the length of our dipoles end to end, making it an easy fit at under 460 feet total. We will put it to the right of the playground with antennas facing 10 degrees south of due west. Even better the 40m antennas can be turned northeast/southwest as needed.

  33. ANY QUESTIONS?

  34. Field Day Antennas, June 2018 40m Phone 15m Dual 20m Phone 40m Digital 20m CW 20m Digital 80m Phone 80m CW 40m CW 10m Dual

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