1. What is dBm?

dBm (decibel-milliwatts) is a unit of power measurement that expresses absolute power in decibels relative to 1 milliwatt. It's commonly used in radio, microwave, and fiber-optic communication networks.

2. How Does the Calculator Work?

The calculator uses the dBm formula:

Where:

• \( V \) — Voltage in volts
• \( R \) — Resistance in ohms
• 1000 — Conversion factor to milliwatts

Explanation: The formula converts voltage to power (using P=V²/R), converts watts to milliwatts (×1000), then converts to logarithmic dBm scale.

3. Importance of dBm Calculation

Details: dBm measurements are crucial in telecommunications for signal strength analysis, system design, and troubleshooting. It provides a consistent reference for power levels across different systems.

4. Using the Calculator

Tips: Enter voltage in volts and resistance in ohms. Both values must be positive numbers. Resistance cannot be zero.

5. Frequently Asked Questions (FAQ)

Q1: What is a good dBm value for WiFi?
A: For WiFi, -30 dBm is excellent, -50 dBm is very good, -60 dBm is good, -67 dBm is minimum for most services, and -80 dBm is poor.

Q2: How does dBm compare to watts?
A: 0 dBm = 1 mW, 10 dBm = 10 mW, 20 dBm = 100 mW, 30 dBm = 1 W. Each 10 dB increase represents a 10× power increase.

Q3: Why use dBm instead of watts?
A: dBm allows easier representation of very large and very small power levels and simplifies calculations in systems with amplifiers and attenuators.

Q4: What's the maximum dBm for typical RF devices?
A: FCC limits WiFi routers to 30 dBm (1W), while cellular phones typically transmit at about 23 dBm (200mW).

Q5: Can dBm be negative?
A: Yes, negative dBm values represent power levels less than 1 milliwatt. For example, -30 dBm = 0.001 mW = 1 μW.