A Quadrifilar Helix Antenna for 137 MHz by KF4CPJ

“After I became a licensed amateur radio operator in August of 1995, I received a QST magazine which had an article that explained it was possible with the right antenna, the Quadrifilar Helix antenna (QHA), to receive the 137 MHz weather satellite transmissions. The article that I read (1) was by an amateur by the name of Buck Ruperto (2), who one year later wrote another terrific article about a program called WxSat (3), that decodes the satellite transmissions (4). After several e-mails back and forth with Buck, I decided to build it. The antenna had fairly good coverage however it was tough to tune and didn’t resonate at the optimum 137 MHz. The received pictures were good however they displayed several deep nulls that always appeared at the same place on the files. I can’t lay the blame on Buck; his design was good it was just tough to replicate.
Over the next year I worked hard to find other outlets for antennas and discovered a web-site (5) that offered plans for a QHA that seemed easier to build. The elements were fashioned from 3/8 soft copper and had known dimensions. After studying the bill of materials and spending ½ a day scrounging for parts, the antenna went together in about 2 ½ hours. The first pictures that I received displayed marked improvement and I have subsequently built a 2^nd QHA for another WxSat enthusiast here in central Florida……”

Read Full Article: