Ham radio

Purpose of Amateur Radio Service

Advancing skills in technical and communication phases of radio art, providing emergency communication service to the public, and enhancing international goodwill.

License Classes

Technician (entry-level), General, Amateur Extra.

Station Identification

Transmitting station call sign must be given every 10 minutes during communication and at the end of a contact.

Control Operator

Must be present at the control point when an amateur station is transmitting.

VHF/UHF Repeater Operation

Repeaters retransmit signals on a different frequency simultaneously to extend range.

Frequency Offset for 2m band

Standard offset is ±600 kHz.

Frequency Offset for 70cm band

Standard offset is ±5 MHz.

CTCSS/PL Tones

Sub-audible audio tones required to open the squelch of many repeaters.

Standard ITU Phonetic Alphabet

Used to clarify call signs (e.g., Alpha, Bravo, Charlie).

QRM

Man-made interference.

QRN

Natural noise.

QSY

Change frequency.

QSO

Conversation.

Wave Characteristics Equation

c = f × λ, where c ≈ 3.00 × 10^8 m/s.

Line-of-Sight Propagation

Primary propagation mode for VHF and UHF frequencies.

Ionospheric (Skywave) Propagation

Bending of HF signals back to Earth by ionospheric layers.

Tropospheric Ducting

Weather conditions causing VHF/UHF signals to travel long distances along temperature inversions.

Ohm's Law

V = I × R (Voltage = Current × Resistance).

Power Equation

P = I × V (Power = Current × Voltage).

Resistor

Limits current flow (measured in ohms, Ω).

Capacitor

Stores energy in an electric field (measured in farads, F).

Inductor

Stores energy in a magnetic field (measured in henries, H).

Diode

Allows current flow in only one direction.

Half-Wave Dipole Antenna Formula

Total length is approximately 468/f in MHz feet.

Quarter-Wave Vertical Antenna

Omnidirectional antenna requiring a radial ground plane.

Coaxial Cable

Standard 50-ohm shielded feedline (e.g., RG-58, RG-8X).

SWR (Standing Wave Ratio)

Ratio of forward to reflected power; a 1:1 ratio indicates a perfect match.

RF Exposure

Non-ionizing radiation limits set by the FCC must be followed.

Grounding

Electrical ground for safety against shock and lightning strikes; RF ground for antenna performance.