The University of Nevada, Reno
Nevada Space Grant
Student
High-Altitude Ballooning

NV SGC
This program is generously supported by the Nevada Space Grant Consortium


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We use a long J-Pole antenna on the secondary communication payload. Since the secondary communications payload is transmitting on the national APRS frequency, the goal is to "hit" as many gates as possible so that the payload location can be tracked on www.findu.com.  If we cannot keep up with the balloon during the chase, we log into findu.com and read the last known packet location. History has shown that we usually the last packet to show up on findu.com is about 1000-2000 feet off the ground, even in very remote parts of Nevada. While not perfect, in a worst-case senario this would minimize the area we need to search for the payload.

The J-pole is made from 300 Ohm twin-lead cable from Radio Shack. We've had two J-poles break during landing, but they are very easy to make. Just Google "twin lead j-pole" and you'll find several good articles on how to construct one (which takes about 30 minutes). This article is for a dual band J-Pole, but Figure 1 shows the dimensions for a 144 MHz only version.