offline - Added simple reference for half-wave dipole

overlay/etc/skel/Desktop/offline/reference/dipole.md

@@ -0,0 +1,42 @@
+---
+title: "Half-Wave Dipole Antenna: Quick Reference"
+date: 2026-03-22
+updated: 2026-03-22
+author: [The Tech Prepper]
+categories: [radio, antennas]
+tags: [dipole, hf, antenna, reference]
+copyright: "(C) 2026 The Tech Prepper, LLC"
+---
+
+The half-wave dipole is a simple and effective HF antenna for field
+deployments.
+
+
+## Formula
+
+**Total Length (feet):**
+
+468 / Frequency (MHz)
+
+**Each Leg:**
+
+234 / Frequency (MHz)
+
+
+## Common Band Lengths (U.S. General Center Cut)
+
+The following are example center frequencies. In most cases, they
+favor the digital portion over the voice portion of the band.
+
+| Band | Frequency (MHz) | Total Length (ft) | Each Side (ft) |
+|------|-----------------|-------------------|----------------|
+| 80m  | 3.5625          | 131.4             | 65.7           |
+| 75m  | 3.900           | 120.0             | 60.0           |
+| 60m  | 5.359           | 87.3              | 43.7           |
+| 40m  | 7.100           | 65.9              | 33.0           |
+| 30m  | 10.125          | 46.2              | 23.1           |
+| 20m  | 14.100          | 33.2              | 16.6           |
+| 17m  | 18.118          | 25.8              | 12.9           |
+| 15m  | 21.100          | 22.2              | 11.1           |
+| 12m  | 24.910          | 18.8              | 9.4            |
+| 10m  | 28.150          | 16.6              | 8.3            |