Explore our collection of 150+ developer tools, PDF editors, and image converters. Everything runs locally in your browser.
Related Developer Tools
Ubify Core Engineering Team
SOFTWARE ENGINEERS & SYSTEMS ARCHITECTS
About This Tool
Impedance mismatches between radio transmitters, coaxial feedlines, and antennas create standing waves that reflect RF power back into final amplifier tubes or transistors. This tool converts VSWR to Return Loss (dB) and calculates true power delivered to antenna terminals across HF, VHF, and UHF bands.
How to Use
- 1
Enter measured antenna VSWR (e.g. 1.2:1 to 3.0:1).
- 2
Select coaxial transmission line type (LMR-400, RG-58, RG-8X, RG-213, RG-6).
- 3
Enter operating frequency (MHz) and feedline length in feet.
- 4
Review Return Loss (dB), percentage of reflected vs transmitted power, and total system attenuation.
Frequently Asked Questions
What is an acceptable VSWR for amateur and two-way radio?
A VSWR under 1.5:1 is considered excellent (less than 4% reflected power). A VSWR between 1.5:1 and 2.0:1 is acceptable for most solid-state transmitters, while anything above 2.5:1 triggers transmitter thermal power rollback.
What is Return Loss in dB?
Return Loss expresses the difference between incident power and reflected power in decibels. A higher Return Loss number indicates a better match: 20 dB Return Loss corresponds to a 1.22:1 VSWR (only 1% reflected power).