HF Frequency Plan
This frequency plan is designed to provide reliable HF communications across Western Australia during emergency operations.
Propagation conditions vary significantly depending on:
- Time of day
- Solar activity
- Season
- Distance between stations
For this reason multiple bands are defined for different conditions.
Operators should select the most appropriate band based on current propagation.
HF Propagation Characteristics in Western Australia
WA operations typically involve communication distances of:
200 km – Local regional coverage
500 km – Regional coordination
1000–2500 km – Statewide communications
Typical propagation behaviour:
Daytime
- 40m supports medium distances
- 20m supports long distances
- 80m becomes unreliable
Night
- 80m becomes primary statewide band
- 40m works well for medium distance
- 20m often closes for domestic paths
Primary HF Net Frequencies
These frequencies are used for statewide coordination.
| Band | Frequency | Mode | Purpose |
|---|---|---|---|
| 40m | 7.110 MHz | LSB | Primary statewide voice net |
| 80m | 3.600 MHz | LSB | Night statewide voice net |
| 20m | 14.300 MHz | USB | Interstate liaison |
Daytime Operations (0700–1800 WST)
Primary Band: 40m
| Frequency | Mode | Purpose |
|---|---|---|
| 7.110 MHz | LSB | Statewide coordination |
| 7.090 MHz | LSB | Alternate coordination |
| 7.130 MHz | LSB | Tactical operations |
Typical daytime coverage on 40m:
Perth → Kalgoorlie
Perth → Geraldton
Perth → Albany
Perth → Pilbara (variable)
Range: 300–1200 km
Night Operations (1800–0700 WST)
Primary Band: 80m
| Frequency | Mode | Purpose |
|---|---|---|
| 3.600 MHz | LSB | Statewide coordination |
| 3.650 MHz | LSB | Alternate coordination |
| 3.580 MHz | LSB | Tactical operations |
Typical night coverage on 80m:
Strong NVIS coverage across most of WA.
Reliable paths:
Perth → Southwest Perth → Wheatbelt Perth → Goldfields Perth → Mid West
Range: 200–800 km
Interstate Coordination
When communicating with eastern states groups, 20m is typically the most reliable band.
| Frequency | Mode | Purpose |
|---|---|---|
| 14.300 MHz | USB | Interstate liaison |
| 14.250 MHz | USB | Alternate liaison |
Digital Messaging Frequencies
These are ideal for structured messages using systems like :contentReference[oaicite:3]{index=3}.
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Digital Messaging Frequencies
| Band | Frequency | Mode | Use |
|---|---|---|---|
| 40m | 7.078 MHz | JS8Call / digital | Messaging |
| 40m | 7.095 MHz | Winlink VARA | Email over HF |
| 80m | 3.595 MHz | digital | Night messaging |
Net Schedule
Regular nets ensure all stations remain informed.
Example schedule:
00 minutes past hour
Statewide situation report
30 minutes past hour
Operational coordination
Additional tactical nets may operate continuously.
Frequency Change Procedure
If interference or poor propagation occurs:
- Net Control announces frequency change
- All stations acknowledge
- Net moves to alternate frequency
Example:
“All stations, move to alternate frequency 7.090 MHz in five minutes.”
Quick Band Selection Guide
Distance < 300 km
Use 80m or VHF
Distance 300–800 km
Use 80m NVIS or 40m
Distance 800–2000 km
Use 40m
Interstate
Use 20m