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HELICAL ANTENNA
TECHNICAL DATA SHEET
Document Number: TM-HELICAL-001 Rev A Equipment: HELICAL ANTENNA Classification: UNCLASSIFIED — Amateur Radio / Field Use Date: 2026-05-24 Supersedes: None (initial issue)
RECORD OF CHANGES
| Change No. | Rev | Date | Description | By |
|---|---|---|---|---|
| 1 | A | 2026-05-24 | Initial formatted release | M. Martin |
Bands: 2M, 70cm, 33cm Approach: Right-hand helical for circular polarization Compaction: 60%
CHAPTER 1 — DESCRIPTION
Right-hand helical for circular polarization
Special parameters: 4–8 turns, ~1.5λ spacing, 50Ω feed
CHAPTER 2 — TECHNICAL CHARACTERISTICS
| Parameter | Value |
|---|---|
| Frequency bands | 2M, 70cm, 33cm |
| Feedpoint impedance | 50–600Ω |
| SWR target | <2:1 |
| Efficiency | 75–95% |
| Gain | 2–12 dBi |
CHAPTER 3 — FABRICATION
- Fabricate wire radiators per NEC model dimensions
- Install tuning elements if applicable
- Construct feed network and matching
- Measure impedance at feed point
- Tune for minimum SWR using dip meter
- Test with transmitter (low power initially)
- Verify SWR and radiation pattern
CHAPTER 4 — TESTING
Use SWR meter and dip meter to verify resonance and impedance matching.
APPENDIX A — TECHNICAL DATA
See helical_specs.csv for exact specifications.
APPENDIX B — DIAGRAMS
See figures/ folder for antenna layout, circuit schematic, and construction detail.
APPENDIX C — NEC MODEL
See helical.nec for electromagnetic simulation.
Navy Technical Manual Level — Generated with NEC2 modeling
Figures
