Foundation Amateur Radio Exam flashcards
Foundation Amateur Radio Exam · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Volunteer Examiners
- Licensed amateurs who administer amateur radio license exams; they are accredited by a Volunteer Examiner Coordinator and must be of equal or higher class than the exam being given.
- Control operator
- The licensed person designated by the station licensee to be responsible for the station's transmissions; both the licensee and control operator share responsibility for rule compliance.
- Station identification
- US amateur stations must transmit their assigned callsign at the beginning and end of each communication and at least every ten minutes during the contact.
- Third-party traffic
- A message sent by an amateur on behalf of an unlicensed person; domestic third-party traffic is generally allowed, but international third-party traffic is restricted unless a treaty permits it.
- Emergency communications
- Any amateur station may use any frequency or mode to provide essential communications during an emergency involving immediate danger to life or property, with appropriate identification.
- Prohibited transmissions
- Amateur stations may not transmit obscenity, profanity, music, broadcasting, or business communications, nor communications for pecuniary interest, except where rules specifically allow.
- License classes
- US amateur licenses progress from Technician to General to Extra; each higher class includes all privileges of lower classes and requires passing additional examination elements.
- Ohm's law
- The relationship V = I × R, where V is voltage in volts, I is current in amperes, and R is resistance in ohms; it underlies all basic circuit analysis.
- Electrical power formula
- Power in watts equals voltage times current (P = V × I); combined with Ohm's law it gives P = I²R and P = V²/R for circuit calculations.
- Parallel resistance
- For resistors in parallel, the reciprocal of total resistance equals the sum of the reciprocals of individual resistances; the total is always less than the smallest branch.
- Wavelength formula
- Wavelength in meters equals 300 divided by frequency in megahertz; thus a 150 MHz signal has a wavelength of about 2 meters.
- Decibel
- A logarithmic ratio used to express power gain or loss; 10 log10(P2/P1) for power, where +3 dB is about double and +10 dB is ten times.
- Capacitor
- A component that stores energy in an electric field, blocks direct current, and passes alternating current; its reactance decreases as frequency increases.
- Inductor
- A component that stores energy in a magnetic field, passes direct current, and opposes changes in current; its reactance increases as frequency increases.
- Resonance
- The condition in a circuit where inductive reactance equals capacitive reactance, so they cancel and the circuit presents a purely resistive impedance at that frequency.
- RMS voltage
- The effective value of an alternating voltage; for a sine wave it equals peak voltage divided by the square root of two, about 0.707 times the peak.
- Modulation
- The process of varying a carrier wave's amplitude, frequency, or phase to carry information; AM varies amplitude, FM varies frequency, and SSB transmits one sideband.
- Single sideband
- A modulation mode that transmits one sideband and suppresses the carrier, giving narrow bandwidth of about 3 kHz and higher efficiency than amplitude modulation.
- FM deviation
- The amount a carrier frequency shifts from its center during FM modulation; greater deviation improves signal-to-noise ratio but widens the occupied bandwidth.
- Receiver sensitivity
- The minimum input signal level a receiver needs to produce an acceptable output; it indicates how weak a signal the receiver can successfully detect and demodulate.
- Receiver selectivity
- A receiver's ability to reject unwanted signals on nearby frequencies and accept only the desired signal, largely determined by its intermediate-frequency filters.
- Superheterodyne receiver
- A receiver design that mixes incoming radio frequencies with a local oscillator to produce a fixed intermediate frequency, where filtering and amplification are applied.
- Mixer
- A circuit that combines two input signals to produce output frequencies equal to their sum and difference; the difference frequency becomes the intermediate frequency.
- Harmonic
- A signal at an integer multiple of a fundamental frequency; unwanted harmonics are spurious emissions that filters and proper tuning help suppress.
- Duty cycle
- The fraction of time a transmitter is at full output; average power equals peak envelope power multiplied by duty cycle, and lower duty cycles reduce heating.
- Dipole length
- A half-wave dipole is approximately 468 divided by frequency in megahertz feet long, or about 143 divided by frequency in megahertz meters.
- Standing wave ratio
- A measure of impedance match between transmitter, feed line, and antenna; 1:1 is perfect, and high SWR reduces radiated power and may stress the transmitter.
- Antenna gain
- The increase in signal strength in a favored direction compared with a reference; expressed in dBi relative to isotropic or dBd relative to a dipole.
- Polarization
- The orientation of an antenna's electric field, horizontal or vertical; transmitting and receiving antennas should share polarization to avoid significant signal loss.
- Ionospheric layers
- Layers named D, E, F1, and F2; the F layer supports long-distance HF sky-wave propagation, while the D layer absorbs lower-frequency signals in daylight.
- Sky-wave propagation
- HF signals radiate upward and refract back to Earth from the ionosphere, enabling long-distance communication beyond the horizon, especially during high sunspot activity.
- Velocity factor
- The ratio of signal speed in a cable to the speed of light in free space; it is used to calculate electrical length and phasing of feed lines and antennas.