segment notes on antennae

zk/Antenna_gain_and_ERP.md

@@ -0,0 +1,48 @@
+---
+tags: [radio, ham-study]
+---
+
+[Antennas](./Types_of_antenna.md) like the Yagi have **gain**. This means they
+can increase the power that they receive from the transmitter via the
+[feeder](./Feeders.md).
+
+Gain is measured in decibels:
+
+| Antenna gain | Power muliplied by a factor of... |
+| ------------ | --------------------------------- |
+| 3dB          | 2                                 |
+| 6dB          | 4                                 |
+| 9dB          | 8                                 |
+| 10dB         | 10                                |
+
+ERP is the **Effective Radiated Power**. This is the product of the power that
+the antenna is receiving from the feeder and the gain level.
+
+> ERP (Watts) = power feed x antenna gain
+
+Some example calculations:
+
+| Gain | Gain times | Power to antenna | ERP       |
+| ---- | ---------- | ---------------- | --------- |
+| 3dB  | x2         | 10 watts         | 20 watts  |
+| 6dB  | x4         | 10 watts         | 40 watts  |
+| 9dB  | x8         | 10 watts         | 80 watts  |
+| 10dB | x10        | 10 watts         | 100 watts |
+
+### ERIP
+
+ERP is calculated relative to the half-wave dipole. This is the benchmark. The
+power that would be generated using this type of antenna.
+
+But, as noted above, the dipole has a distinct radiation pattern - diffusing in
+poles at right angles to the horizontal plane of the antenna.
+
+By being tied to the dipole, ERM is therefore not the most universal or
+objective unit of measurement.
+
+To remedy this, there is another unit: ERIP. This stands for **Effective
+Isotropic Radiated Power**. It's the same calculation but it uses a theoretical
+antenna that would radiate equally in all directions as the benchmark.
+
+Because of the equal radiation pattern in all directions, EIRP will always be
+higher than ERP. Roughly speaking, 10 Watts in EIRP would be 6 Watts in ERP.

zk/Antenna_polarisation.md

@@ -0,0 +1,12 @@
+---
+tags: [radio, ham-study]
+---
+
+**Polarisation** means whether the antenna is positioned on a vertical or
+horizontal plane.
+
+Of the antennas covered at foundation level, only dipoles and Yagis can be
+positioned at variable polarities.
+
+VHF and UHF are received most effectively when the transmitter and receiver have
+the same antenna polarisation.

zk/Foundation_licence_conditions.md

@@ -2,10 +2,12 @@
 tags: [radio, ham-study]
 ---
 
-- Business and any commercial activity is not permitted
 - An amateur radio licence is _only for self-training in radio communications_
-- Ofcom is the UK TV and radio regulator
+- Business and any commercial activity is not permitted
-- Ofcom issues amateur radio licences
+- Ofcom is the UK TV and radio regulator and the body that issues amateur
+  licenses
+
+## Ofcom rules
 
 **You must**:
 
@@ -22,7 +24,19 @@ tags: [radio, ham-study]
 - in cases of reported interference, ask you to log the transmissions you have
   made over a specified time period
 
-**Acceptable operating locations**:
+## The following types of activity are not permitteed
+
+- Business or commercial activity
+- The use of encryption or codes, other than Morse Code
+- Broadcasting, defined as "transmitting for general reception" (e.g. this would
+  constitute "pirate radio")
+  - The only scenario where broadcasting is permitted is during the CQ stage,
+    when you are seeking a contact to talk to
+  - Or when you are operating a "Net", defined as a conversation between three
+    or more amateurs where communication is first established with at least one
+    individual member of the net
+
+## Acceptable operating locations
 
 - UK
 - Channel Islands
@@ -33,3 +47,18 @@ they are in international water or airspace. (Note that TX from aircraft has
 power restrictions as specified in Schedule 1 listings.)
 
 The Foundation licence does not permit operating in any other countries.
+
+## EMF rules
+
+> "EMF" stands for _electromagnetic field_
+
+The Foundation licence specifies that amateur equipment must not expose the
+public to EMF over a certain threshold. This threshold is **10 Watts
+[ERIP](/zk/Antennas.md) or approximately 6.1 Watts ERP**.
+
+All amateurs must complete an EMF assessment to demonstrate they are operating
+within the required limits. Ofcom can request an assessment at any time.
+
+If you are likely to exceed the threshold you must demonstrate that actions are
+being taken to ensure the limits are maintained. If no provisions are necessary,
+you specify that "power levels are below the threshold".

zk/Types_of_antenna.md

@@ -75,60 +75,3 @@ In contrast to the others, the Yagi is directional and focused in one direction
 It basically works as a dipole with a reflector behind it. This helps to push
 the waves in the horizontal direction of travel, assisted by the director spoke
 in front.
-
-### Gain and ERP
-
-Antennas like the Yagi have **gain**. This means they can increase the power
-that they receive from the transmitter via the [feeder](./Feeders.md).
-
-Gain is measured in decibels:
-
-| Antenna gain | Power muliplied by a factor of... |
-| ------------ | --------------------------------- |
-| 3dB          | 2                                 |
-| 6dB          | 4                                 |
-| 9dB          | 8                                 |
-| 10dB         | 10                                |
-
-ERP is the **Effective Radiated Power**. This is the product of the power that
-the antenna is receiving from the feeder and the gain level.
-
-> ERP (Watts) = power feed x antenna gain
-
-Some example calculations:
-
-| Gain | Gain times | Power to antenna | ERP       |
-| ---- | ---------- | ---------------- | --------- |
-| 3dB  | x2         | 10 watts         | 20 watts  |
-| 6dB  | x4         | 10 watts         | 40 watts  |
-| 9dB  | x8         | 10 watts         | 80 watts  |
-| 10dB | x10        | 10 watts         | 100 watts |
-
-### ERIP
-
-ERP is calculated relative to the half-wave dipole. This is the benchmark. The
-power that would be generated using this type of antenna.
-
-But, as noted above, the dipole has a distinct radiation pattern - diffusing in
-poles at right angles to the horizontal plane of the antenna.
-
-By being tied to the dipole, ERM is therefore not the most universal or
-objective unit of measurement.
-
-To remedy this, there is another unit: ERIP. This stands for **Effective
-Isotropic Radiated Power**. It's the same calculation but it uses a theoretical
-antenna that would radiate equally in all directions as the benchmark.
-
-Because of the equal radiation pattern in all directions, EIRP will always be
-higher than ERP. Roughly speaking, 10 Watts in EIRP would be 6 Watts in ERP.
-
-## Antenna polarisation
-
-**Polarisation** means whether the antenna is positioned on a vertical or
-horizontal plane.
-
-Of the antennas covered at foundation level, only dipoles and Yagis can be
-positioned at variable polarities.
-
-VHF and UHF are received most effectively when the transmitter and receiver have
-the same antenna polarisation.