An antenna datasheet is a simple summary of how an antenna performs. Every number on it describes how the antenna works under specific conditions. Frequency ranges, gain figures, VSWR ratios and impedance values all tell a different part of it. Once you understand what each measure means you can compare two models side by side and actually know which one fits your needs better.
Understanding Antenna Frequency Range
This tells you the lower and upper frequency limits the antenna covers. A Military Log Periodic Dipole Antenna rated at 20 MHz to 3000 MHz means it performs within that band. Outside those limits performance drops off and the antenna becomes less effective.
How Antenna Gain Works
Gain is measured in dBi. It tells how better an antenna focuses signal energy in some specific direction. A High Gain Log Periodic Antenna with 10 dBi focuses energy more better than an antenna with 5 dBi one.
Why VSWR Matters
VSWR (Voltage Standing Wave Ratio) is a rating of 1.5:1 means that most power reaches the antenna with very little reflection back into the transmitter. Anything above 2:1 starts wasting power. Most Military Discone Antenna and LPDA models aim for VSWR for less than 2:1 across their rated band.
Understanding Antenna Polarization
Polarization tells you the orientation in which the antenna transmits or receives electromagnetic waves. A Dual Polarized Log Periodic Antenna handles both vertical and horizontal polarization at the same time. This gives it a clear advantage in SIGINT and electronic warfare roles.
Why Impedance Matters
Most antennas are rated at 50 ohms. This needs to match your cable and receiver to avoid signal loss. Mismatched impedance causes reflections and directly affects performance across any wideband antenna setup.