04/27/2016
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[1]). 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.
[1] http://www.wssef.org/
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