KU Abstract 2014-Design & Construction of a Low-Cost, High-Gain Antenna
Student Researchers: Tara Sacerdote, Lawrence Free State High School, Lawrence KS
Laura Neilsen, Lawrence Free State High School, Lawrence KS
Kaustubh Nimkar, Lawrence High School, Lawrence KS
Christoph Kinzel, Olathe North High School, Olathe KS
Research Teacher Mentor: James Deane, Ottawa High School, Ottawa KS
Research Mentor: Prof. Dave Besson, University of Kansas, Lawrence KS
Steven Prochyra, University of Kansas
The purpose of our work this summer was to design and build an antenna that would allow us to receive a signal from Greg Cerny, WQ0P, an amateur radio operator in Belvue, Kansas, approximately 84 km from our location, transmitting at a frequency of 222 megahertz.
In order to do this, we learned how to use the computer program Numerical Electromagnetics Code (4NEC2), which enabled us to design and optimize a ten-element Yagi-Uda antenna with high gain at 222 MHz. NEC provided the dimensions for maximum gain and we obtained the materials required to physically construct a spectacular antenna, which were limited to aluminum foil, polyvinyl chloride (PVC) pipe, wooden dowel rods and planks, and a coaxial cable. The cost of materials (minus the cable) totaled less than twenty dollars.
The experimentally observed gain pattern of our completed antenna did not exactly mirror the projected gain pattern from the NEC file, but showed front, back, and side lobes consistent with real world Yagi-Uda antenna gain patterns. After coordinating with our transmitter, we set up the antenna on the roof of Malott Hall, and received a strong signal from Belvue. Based on the Friis transmission equation, the calculated received power was 8.675x10-10 watts. Unfortunately, since our radio has automatic gain control (AGC), determining the actual signal level from the Belvue transmitter is impossible. However, the minimum power that our radio can detect is 3.199x10-13 watts, an appreciably lower value than the projected received power and that supports the 8.675x10-10 watt figure.
Meaning and Further Study:
Since we did successfully build a cheap, durable, powerful antenna, future communication with amateur radio operators, as well as earth-moon-earth communication, or moonbounces, are possible. Additionally, the inexpensiveness and simplicity of this project would lend itself easily to advanced high school physics classes looking to explore radio and antenna design.