From Smith Charts to Antennas: Exploring RF Systems Hands on!

I had the opportunity to dive deep into the world of Radio Frequency (RF) Engineering through a comprehensive lab course. The lab gave me hands-on experience working with RF components, transmission lines, S-parameters, and antennas—all supported by industry-standard measurement tools like vector network analyzers, spectrum analyzers, function generators, and oscilloscopes. From coaxial lines to horn antennas, I analyzed how energy behaves at high frequencies—bridging the gap between theoretical electromagnetic systems and real-world RF circuits.

What I Explored:

• Coaxial Transmission Lines
  • Measured standing wave ratio (VSWR) and reflection coefficients using a movable E-field probe.
  • Investigated the effect of various terminations (open, short, matched, capacitive, resistive) on wave propagation.
  • Used a spectrum analyzer to visualize spatial electric fields and wave patterns.
  • Applied Smith Chart analysis to calculate load impedances and matching strategies.
• Time Domain Reflectometry
  • Used rectangular pulses and a 74F3037 line driver to observe signal reflections from coaxial cables under various load conditions.
  • Measured rise/fall times, propagation delays, and calculated dielectric constants.
  • Determined unknown cable lengths and analyzed the effects of capacitive and inductive terminations.
• S-Parameters and Network Analysis
  • Calibrated and operated a vector network analyzer (VNA) to measure S-parameters of filters, microstrip lines, circulators, and power dividers.
  • Displayed S11 (reflection) and S21 (transmission) using both magnitude/phase and Smith chart formats.
  • Investigated a 3-port resistive divider and circulators, exploring port isolation and impedance matching.
• Antenna Characteristics and Radiation Patterns
  • Measured radiation patterns of horn antennas and phased antenna arrays at 1, 2, and 3 GHz.
  • Compared antenna patterns with equal-phase and phase-shifted feeds.
  • Analyzed real antenna behavior using theoretical models in MATLAB and Excel, comparing gain and directivity with actual lab results.

Skills Demonstrated:

• RF measurement using VNA, TDR, spectrum analyzer, and oscilloscope
• Smith chart interpretation and impedance transformation
• Matching network design (transmission line + capacitor)
• Understanding of microstrip design principles and their real-world applications
• Radiation pattern measurement and phased antenna theory
• Proficiency in high-frequency signal handling and system calibration