Ohm's Law & Power
Select an equation from the wheel to solve for a specific variable.
Reactance (X)
Calculate inductive or capacitive reactance for a given frequency.
Inductive Reactance
X_L = 2πfL
Inductive Reactance (XL):
0 Ω
Capacitive Reactance
X_C = 1 / (2πfC)
Capacitive Reactance (XC):
0 Ω
Parallel Tank (LC)
f0 = 1 / (2π√LC)
Resonant Frequency (f0):
0 Hz
Impedance at Resonance (XL ∥ XC):
0 Ω
Series Tank (LC)
f0 = 1 / (2π√LC)
Resonant Frequency (f0):
0 Hz
Impedance at Resonance (XL + XC):
0 Ω
Complex Impedance (RLC)
Calculate the complex impedance of R, L, and/or C combined in series or parallel at a given frequency. Leave a component blank to exclude it from the circuit.
Impedance (magnitude & phase):
0 Ω ∠ 0°
Impedance (rectangular, Z = R + jX):
0 + j0 Ω
Character:
—
XL = 0 Ω
XC = 0 Ω
PCB Trace Impedance
Single-ended characteristic impedance for microstrip and grounded coplanar waveguide (GCPW) PCB traces. These are quasi-static closed-form approximations — typically ±5–15% accuracy. Verify with a field solver (or your fab's stackup calculator) for critical designs.
Microstrip
IPC-2141: Z0 = (87/√(εr+1.41))·ln(5.98H / (0.8W+T))
Characteristic Impedance (Z0):
0 Ω
Grounded Coplanar Waveguide (GCPW)
Conformal-mapping model with Hilberg's elliptic-integral-ratio approximation
Characteristic Impedance (Z0):
0 Ω
Effective Dielectric Constant (εeff):
0
Stripline (Symmetric)
IPC-2141: Z0 = (60/√εr)·ln(1.9B / (0.8W+T))
Assumes trace is centered between planes (B = 2H)
Characteristic Impedance (Z0):
0 Ω
Differential Microstrip
Zdiff = 2·Z0·(1 − 0.48·e−0.96·S/H)
Differential Impedance (Zdiff):
0 Ω
Single-Ended Impedance (Z0):
0 Ω
Differential Stripline
Zdiff = 2·Z0·(1 − 0.347·e−2.9·S/B)
Assumes trace is centered between planes (B = 2H)
Differential Impedance (Zdiff):
0 Ω
Single-Ended Impedance (Z0):
0 Ω
Differential GCPWG (Approximate)
Zdiff ≈ 2·Z0·(1 − 0.48·e−0.96·S/G), Z0 from the GCPWG conformal-mapping model above
No validated closed-form for coupled/differential GCPWG was available to build this from. The coupling correction is adapted from the microstrip case and is a rough estimate only — confirm with a field solver before use.
Differential Impedance (Zdiff):
0 Ω
Single-Ended Impedance (Z0):
0 Ω
Free Space Path Loss (FSPL)
Calculate RF signal loss over distance in free space.
Path Loss:
0 dB
Resistor Divider
Calculate the output voltage of a voltage divider circuit, or solve for R1/R2 given a target output.
Tolerance & Temperature Drift (optional)
Worst-case stacking of initial tolerance + TCR drift from a 25°C reference, over the temperature range below. Leave R1/R2 tolerance and TCR blank to skip.
Pi Attenuator (Pad)
Design a symmetric resistive Pi pad for a target attenuation, or analyze an existing R1/R2 pair to find its attenuation and impedance.
R1 = shunt legs (one at each port, both the same value) · R2 = series arm
Design: dB → Resistors
K = 10^(dB/20)
R1 — shunt (×2), exact:
0 Ω
Nearest E192: —
R2 — series, exact:
0 Ω
Nearest E192: —
Actually delivered by the E192 pair:
—
Analyze: Resistors → dB
Z₀ = R1√(R2 / (2R1 + R2))
Attenuation (matched):
0 dB
Design (image) impedance Z0:
0 Ω
Zin (OUT terminated):
0 Ω
Zout (IN terminated):
0 Ω
The attenuation shown is the matched value, obtained when the pad is driven from and terminated in its design impedance Z0. A symmetric Pi is reciprocal, so Zin and Zout are equal for equal terminations; both collapse to Z0 when the termination equals the design impedance.
dBm / dBW Power Converter
Convert between RF power level (dBm/dBW) and Watts, and see the equivalent RMS voltage across a 50Ω or 75Ω load. Edit either the Power Level or Power field.
Voltage (RMS) @ 50Ω:
0 V
Voltage (RMS) @ 75Ω:
0 V
Wavelength / Frequency
Convert between frequency and free-space wavelength (λ = c / f). Edit either field.
RC Time Constant
Calculate the time constant and -3dB cutoff frequency of a resistor-capacitor network.
Time Constant (τ = RC):
0 s
Cutoff Frequency (fc = 1 / 2πRC):
0 Hz
VSWR / Return Loss
Convert between VSWR and Return Loss for an impedance mismatch. Edit either field.
Reflection Coefficient (Γ):
0
Antenna Designer
Calculate resonant dipole and monopole element lengths from free-space wavelength, adjusted by a velocity/end-effect factor.
Dipole (Half-Wave)
L = (c / 2f) × k
Total Length (tip to tip):
0 ft (0 m)
Each Leg (from center feedpoint):
0 ft (0 m)
Monopole (Quarter-Wave)
L = (c / 4f) × k
Element Length (base to tip):
0 ft (0 m)
Measured over an adequate ground plane / radial system.
Complex Conjugate Match
Find the ideal load impedance for maximum power transfer from a given source, the mismatch into 50Ω, and L-network matching components.
Source Impedance
Zs = Rs + jXs
Conjugate Match
Zmatch = Rs − jXs
Ideal Load Impedance:
—
|Γ| into 50Ω: —
VSWR: —
Return Loss: —
Mismatch Loss: —
L-Network to 50Ω
Series element, then shunt to ground on the load side.
High-Pass (C + L):
—
Low-Pass (L + C):
—