📡 Frequency Bandwidth Calculator
Calculate signal bandwidth and related parameters
Highest frequency in the band
Lowest frequency in the band
How to Use This Calculator
Enter Upper Frequency
Input the highest frequency in the frequency band or signal range, in Hertz (Hz). This is the upper cutoff frequency or maximum frequency of interest.
Enter Lower Frequency
Input the lowest frequency in the frequency band or signal range, in Hertz (Hz). This is the lower cutoff frequency or minimum frequency of interest.
Calculate
Click the "Calculate Bandwidth" button to get the bandwidth, center frequency, fractional bandwidth (as percentage), and Q factor. Bandwidth indicates the range of frequencies the signal occupies.
Formula
BW = fupper - flower
fcenter = (fupper + flower) / 2
Q = fcenter / BW
Where:
- BW = Bandwidth (Hertz, Hz)
- fupper = Upper Frequency (Hz)
- flower = Lower Frequency (Hz)
- fcenter = Center Frequency (Hz)
- Q = Quality Factor (dimensionless)
Example Calculation:
For a signal band from 900 MHz to 1100 MHz:
fupper = 1.1 × 10⁹ Hz
flower = 9 × 10⁸ Hz
BW = 1.1×10⁹ - 9×10⁸ = 2×10⁸ Hz = 200 MHz
fcenter = (1.1×10⁹ + 9×10⁸) / 2 = 1×10⁹ Hz = 1 GHz
Q = 1×10⁹ / 2×10⁸ = 5
Note: Higher Q indicates a narrower bandwidth relative to center frequency (more selective). Lower Q indicates a wider bandwidth (less selective, more broadband).
About Frequency Bandwidth Calculator
The Frequency Bandwidth Calculator determines the bandwidth of a signal, filter, or communication channel, along with related parameters like center frequency, fractional bandwidth, and Q factor. Bandwidth is the range of frequencies over which a signal operates or a system responds, and is fundamental to signal processing, communications, and filter design.
When to Use This Calculator
- Signal Processing: Calculate bandwidth of signals and determine frequency range
- Filter Design: Analyze bandwidth and Q factor of filters and resonant circuits
- Communication Systems: Determine channel bandwidth and frequency allocation
- Antenna Design: Calculate bandwidth of antennas and matching networks
- RF Engineering: Analyze frequency response and bandwidth requirements
Why Use Our Calculator?
- ✅ Quick Calculation: Instantly determine bandwidth from frequency limits
- ✅ Multiple Parameters: Calculates bandwidth, center frequency, fractional bandwidth, and Q factor
- ✅ Signal Analysis: Essential for understanding signal characteristics and system response
- ✅ Free Tool: No registration or payment required
- ✅ Educational: Learn about bandwidth, Q factor, and frequency analysis
Common Applications
Communication Channels: Determine the bandwidth of communication channels like WiFi (20 MHz, 40 MHz, 80 MHz), cellular (5 MHz, 10 MHz, 20 MHz), and broadcast channels. Bandwidth directly relates to data capacity - wider bandwidths can carry more information, making this crucial for network planning and capacity analysis.
Filter Design: Calculate the bandwidth of filters to understand their frequency selectivity. High-Q filters (narrow bandwidth) are used for frequency selection in radios and signal processing, while low-Q filters (wide bandwidth) are used for signal conditioning and noise filtering.
Antenna Bandwidth: Analyze the bandwidth over which antennas operate effectively, typically defined as the frequency range where performance (like VSWR < 2:1) is acceptable. Wider bandwidth antennas are more versatile but often have trade-offs in other performance parameters.
Tips for Best Results
- Bandwidth is always positive and represents the frequency range
- Higher Q factor means narrower bandwidth relative to center frequency (more selective)
- Fractional bandwidth shows bandwidth as percentage of center frequency
- For 3-dB bandwidth, use frequencies where response is 3 dB below peak
- Wider bandwidth allows higher data rates but may increase noise
Frequently Asked Questions
What is bandwidth?
Bandwidth is the range of frequencies over which a signal operates or a system responds effectively. It's the difference between the upper and lower frequency limits: BW = fupper - flower. It determines how much information a signal can carry or how selective a filter is.
What is the Q factor?
Q (quality factor) is the ratio of center frequency to bandwidth: Q = fcenter / BW. High Q (Q > 10) indicates narrow bandwidth and high selectivity. Low Q (Q < 1) indicates wide bandwidth. Q factor relates to how sharp a filter's response is or how selective a resonant circuit is.
What is fractional bandwidth?
Fractional bandwidth is bandwidth expressed as a percentage of center frequency: FBW = (BW / fcenter) × 100%. It's useful for comparing bandwidths at different center frequencies. A 100 MHz bandwidth is narrow for 10 GHz (1%) but wide for 1 MHz (10%).
What's the difference between absolute and relative bandwidth?
Absolute bandwidth is the frequency range in Hz (e.g., 200 MHz). Relative bandwidth is bandwidth relative to center frequency, often expressed as fractional bandwidth or percentage. Both are useful - absolute for system specifications, relative for comparing systems at different frequencies.
How does bandwidth relate to data rate?
According to Shannon's theorem, maximum data rate C = B × log₂(1 + SNR), where B is bandwidth and SNR is signal-to-noise ratio. Wider bandwidth allows higher data rates, which is why high-speed communications use wide bandwidths (e.g., 5G uses up to 100 MHz or more).
What is 3-dB bandwidth?
3-dB bandwidth is the frequency range where the response is within 3 dB of the peak (half power points). It's the most common definition of bandwidth for filters and frequency responses. If your frequencies are 3-dB points, use them directly in this calculator.