Update for 11-11-21 16:30

tech/Ham.wiki

@@ -33,4 +33,4 @@ see [[electronics]]
 
 == Signals ==
 
-
+[[Propagation]]

tech/Propagation.wiki

@@ -0,0 +1,38 @@
+= Propagation =
+
+Radio Propagation is how signals from the antenna move through space.
+
+Some notes
+
+* VHF/UHF can be absorbed by leaves, so they travel farther during winter
+* Fog and rain absorb UHF
+
+* VHF/UHF can interfere with each other, leading to dead spots and blending.
+  When moving this can happen quickly (as dead spots are ~1/2 a wavelength
+  apart) and cause a fluttering
+
+== Ionoshpere ==
+
+The ionosphere is a region 30-260 miles above the earth that contains charged
+O2 and N2 (from being bombed with UV, they are conductive).
+
+=== Layers ===
+
+The Ionosphere has layers that can reflect different wavelengths. Usually more
+reflection is done at night, as the sun charges the particles and allows them
+to bounce the signals. Sun spots also increase this activitity.
+
+Below are the list of layers
+
+| Layer | Altitude | Notes |
+----------------------------
+| D  | 30-60 mi  | Often absorbs most signals      |
+| E  | 60-70 mi  | Reflects VHF/UHF, up to 1200 mi |
+| F1 | 70-140 mi | Only exists during the day      |
+| F2 | 140+ mi   | Combines with F1 at night       |
+
+Note
+
+* E skip of E,,s,, happens most duirng early summer and mid winter 
+  - 10, 6, and 2 meters only
+  - This is what makes HF so good at long distance comms

tech/frequency_range.wiki

@@ -23,3 +23,7 @@ c is speed of light (3 * 10^8 m/s)
 f is frequency
 
 A shorthand is 
+
+WL = 300 / f
+
+Where f is in Mhz