A 10-year-old ARRL member from Snoqualmie, Washington, took first place in his grade and division for a magnetic loop antenna project he entered into the Washington State Science and Engineering Fair (WSSEF). Dragan Tuip, KG7OQT, was among the more than 700 presenters at the fair, held April 1-2 in Bremerton. A 5th grade student at Yellow Wood Academy in Mercer Island, his project, “Modular HF Mag Loop Antenna,” stemmed from his desire for a compact antenna to use in his room with his HF transceiver — a flea market bargain. According to his dad, Martin Tuip, KG7HAX, Dragan built the antenna himself and successfully tested by making JT65 contacts with Japan and Georgia. The 59th annual WSSEF marked Dragan’s science fair debut.
“When they called my name during the award ceremony, I was stunned! I was amazed!” he told ARRL. “I learned that not everything is always the best, and some things still have room for improvement. I had several people already ask me if they could buy the antenna.” One of his goals is to earn DXCC before he turns 11. He eventually hopes to market the antenna.
The magnetic loop design he entered into the science fair consists of a 10-foot circumference loop of LMR-400 coaxial cable with a 2-foot circumference loop of solid copper and a variable capacitor for tuning housed in a central enclosure. He reports the antenna is usable on 40, 30, 20, 17 and 15 meters with a low SWR. The antenna can handle up to about 10 W for 100 percent duty cycle modes, and up to 15 W PEP for SSB.
The need for an indoor antenna arose after his mom let it be known that she didn’t want any new holes drilled in the house nor any more visible antennas. “He tried a few of the HamSticks that I have lying around, but they were simply too big to fit,” his father said. Dragan had seen some mag loop-style antennas in articles his dad had been reading and asked if something like that might fit in his room.
“I told him that that size would work, and off he went to scavenge the house for parts to build a prototype,” Martin Tuip said. “We had to order a capacitor for the prototype, and he built further upon that.” Dragan did all the calculations for the wire lengths involved, he said.
“He ran propagation tests using WSPR with my G5RV as reference, and the mag loop was about 80 percent as effective at a fraction of the size,” Martin Tuip said. “The outer loop has to be less than 0.10 l on the lowest design band, while the inner loop has to be 0.20 the size of the main loop.
The WSSEF awards more than $1.8 million in scholarships as well as special awards meeting a sponsor’s specific criteria. WSSEF is an all-volunteer non-profit organization dedicated to promoting science, technology, engineering and math across the state year-round. Dragan has been licensed since he was 8 and obtained his General ticket a year later. He presented on Amateur Radio at last year’s Northwest Overland Expo, a large international gathering for remote expedition travel enthusiasts.
Jim makes and then shows his tunable half wavelength dipole antenna. Using an antenna analyzer, Jim finds the resonant frequency and the lowest SWR do not occur at the same frequency. Read more
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