This category covers 13 topics and has 44 questions.

• Factors Affecting Reception
• HF Skip Distance
• HF Comms (skywaves)
• HF Comms (skip Distance)
• VDF Accuracy
• VDF Q Codes
• VDF Reference
• VDF Fix
• VDF Info
• VDF Equipment
• VDF Variation
• VDF Detection
• VHF and HF Characteristics