RF Fundamentals
Build the foundations to reason about RF circuits and wireless systems. Connect frequency, power and impedance to electromagnetic fields and receiver noise through interactive models and worked examples, including practical cases at 2.45 GHz.
- 5 lessons
- 6–8 hours estimated
All five lessons are free and open without an account. A free verified account is required for the Example Exam and supervised exams.
- Who it’s for
- Engineers, students and makers building on their electronics knowledge or refreshing the fundamentals.
- Useful prerequisites
- Voltage, current, resistance, basic algebra, and SI units.
What you’ll learn
Frequency & signals
Calculate wavelength, delay, and phase from frequency and distance.
Power & impedance
Describe power and impedance with the right units and measurement location.
Fields & waves
Connect circuit behavior to fields, propagation, and polarization.
Receiver noise
Calculate receiver noise and check a signal-to-noise requirement.
Explore the five lessons.
Each lesson combines explanations, interactive models, worked examples, and practice.
New to RF? Follow the lessons in order. For a refresher, open an outline and jump to the concept you need.
- 01
RF Signals
Frequency, wavelength, amplitude, phase, and spectrum.
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- 02
RF Power
Connect energy, RMS, watts, decibels, signal chains, and real power measurements.
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- What exactly is RF power?
- How a sinusoid delivers energy
- RMS: the amplitude that predicts heating
- From voltage to power: the load and measurement point
- Why RF engineers use decibels
- dBm and dBW: absolute levels with fixed references
- Gain and loss through an RF chain
- Why voltage ratios use 20 log
- dBc: relative to a carrier
- How separate powers combine
- Average, burst, peak, and measured power
- Apply it: calculate and report RF power
- 03
Impedance & Reactance
Understand how components oppose RF current and how resonance shapes circuits.
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- Why resistance is no longer enough
- Resistance and real power transfer
- Capacitance: energy in an electric field
- Inductance: energy in a magnetic field
- Same RMS values. Different average power.
- Reactance: how inductors and capacitors respond to frequency
- Complex impedance: magnitude and phase together
- Combining impedances without losing phase
- Resonance: when L and C cancel at the input
- Q, bandwidth, and ring-down
- Real RF components are not ideal components
- Measuring impedance
- Put it together: a series RLC circuit
- 04
Fields & Waves
Relate voltage and current to electromagnetic fields, and predict how distance and antenna orientation affect a received signal.
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- Electric fields and force
- Magnetic fields and flux
- Changing fields act on circuits
- How electromagnetic waves travel
- Fields carry power
- Materials and wave speed
- Reflection, absorption and skin depth
- Receiver orientation and polarization
- From antenna power to field strength
- Apply it: explain a receiver’s signal
- 05
Noise
Quantify the random energy that limits every receiver and measurement.
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- Noise sets the weak-signal limit
- Random signals have measurable structure
- From noise density to noise power
- Thermal noise and the −174 dBm/Hz reference
- Noise sources leave different fingerprints
- Phase fluctuations around a carrier
- What a spectrum analyzer actually displays
- SNR, C/N, C/N₀, and SINR
- Noise factor, noise figure, and equivalent temperature
- Why receiver stage order matters
- Antenna temperature and receiver sensitivity
- Apply it: receiver margin with a colder source
Assessment & certification
Check your understanding with a free practice assessment. Earn a certificate by passing a separate one-hour exam supervised by Ricardo Pereira.
A free verified account is required for all exams. Certification: at least 18/20 and supervisor confirmation. Practice does not earn a certificate.