# Models of HF Interference over Cyprus
## 2 Materials and Methods
\begin{table}
\begin{tabular}{c c c c c} \hline
**Code** & **Primary Users** & **Frequency (MHz)** & **Code** & **Primary Users** & **Frequency (MHz)** \\ \hline
1 & FIXED/MOBILE & 1.606–1.810 & 49 & FIXED/MOBILE & 13.800–14.000 \\
2 & AMATEUR & 1.810–1.850 & 50 & AMATEUR & 14.000–14.350 \\
3 & FIXED/MOBILE & 1.850–2.045 & 51 & FIXED/MOBILE & 14.350–15.000 \\
4 & FIXED/MOBILE & 2.045–2.300 & 52 & AEROMOBILE & 15.000–15.100 \\
5 & FXD./MOB./BCST. & 2.300–2.500 & 53 & BROADCAST & 15.100–15.600 \\
6 & FIXED/MOBILE & 2.500–2.850 & 54 & FIXED & 15.600–16.000 \\
7 & AEROMOBILE & 2.850–3.155 & 55 & FIXED & 16.000–16.360 \\
8 & FIXED/MOBILE & 3.155–3.200 & 56 & MARITIME/MOB. & 16.360–16.860 \\
9 & FXD./MOB./BCST. & 3.200–3.400 & 57 & MARITIME/MOB. & 16.860–17.410 \\
10 & AEROMOBILE & 3.400–3.500 & 58 & FIXED & 17.410–17.550 \\
11 & FXD./MOB./AMTR. & 3.500–3.800 & 59 & BROADCAST & 17.550–17.900 \\
12 & FIXED/MOBILE & 3.800–3.900 & 60 & AEROMOBILE & 17.900–18.030 \\
13 & AEROMOBILE & 3.900–3.950 & 61 & FIXED & 18.030–18.068 \\
14 & FIXED/OST. & 3.950–4.000 & 62 & AMATEUR & 18.068–18.168 \\
15 & MARITIME/MOB. & 4.000–4.438 & 63 & FIXED/MOBILE & 18.168–18.780 \\
16 & FIXED/MOBILE & 4.438–4.650 & 64 & MARITIME/MOB. & 18.780–18.900 \\
17 & AEROMOBILE & 4.650–4.750 & 65 & FIXED & 18.900–19.300 \\
18 & FXD./MOB./BCST. & 4.750–5.060 & 66 & FIXED & 19.300–19.680 \\
19 & FIXED/MOBILE & 5.060–5.480 & 67 & MAR/MOB. & 19.680–19.800 \\
20 & AEROMOBILE & 5.480–5.730 & 68 & FIXED & 19.800–20.000 \\
21 & FIXED/MOBILE & 5.730–5.950 & 69 & FIXED/MOBILE & 20.000–20.500 \\
22 & BROADCAST & 5.950–6.200 & 70 & FIXED/MOBILE & 20.500–21.000 \\
23 & MARITIME/MOB. & 6.200–6.525 & 71 & AMATEUR & 21.000–21.450 \\
24 & AEROMOBILE & 6.525–6.765 & 72 & BROADCAST & 21.450–21.870 \\
25 & FIXED/MOBILE & 6.765–7.000 & 73 & AEROMOBILE & 21.870–22.000 \\
26 & AMATEUR & 7.000–7.100 & 74 & MAR/MOB. & 22.000–22.400 \\
27 & BROADCAST & 7.100–7.300 & 75 & MAR/MOB. & 22.400–22.855 \\
28 & FIXED/MOBILE & 7.300–7.800 & 76 & FIXED & 22.855–23.000 \\
29 & FIXED/MOBILE & 7.800–8.195 & 77 & FIXED/MOBILE & 23.000–23.200 \\
30 & MARITIME/MOB. & 8.195–8.500 & 78 & AEROMOBILE & 23.200–23.350 \\
31 & MARTITIME/MOB. & 8.500–8.815 & 79 & FIXED/MOBILE & 23.350–24.000 \\
32 & AEROMOBILE & 8.815–9.040 & 80 & FIXED/MOBILE & 24.000–24.500 \\
33 & FIXED & 9.040–9.500 & 81 & FIXED/MOBILE & 24.500–24.890 \\
34 & BROADCAST & 9.500–9.900 & 82 & AMATEUR & 24.890–25.000 \\
35 & FIXED & 9.900–10.000 & 83 & MAR/MOB. & 25.000–25.210 \\
36 & AEROMOBILE & 10.000–10.100 & 84 & FIXED/MOBILE & 25.210–25.550 \\
37 & FIXED/AMATEUR & 10.100–10.150 & 85 & RAD/ASTR & 25.550–25.670 \\
38 & FIXED/MOBILE & 10.150–10.600 & 86 & BROADCAST & 25.670–26.100 \\
39 & FIXED/MOBILE & 10.600–11.175 & 87 & MAR/MOB. & 26.100–26.175 \\
40 & AEROMOBILE & 11.175–11.400 & 88 & FIXED/MOBILE & 26.175–26.500 \\
41 & FIXED & 11.400–11.650 & 89 & FIXED/MOBILE & 26.500–27.000 \\
42 & BROADCAST & 11.650–12.050 & 90 & FIXED/MOBILE & 27.000–27.500 \\
43 & FIXED & 12.050–12.230 & 91 & FXD./MOB./METR. & 27.500–28.000 \\
44 & MARITIME/MOB. & 12.230–12.730 & 92 & AMATEUR & 28.000–28.500 \\
45 & MARITIME/MOB. & 12.730–13.200 & 93 & AMATEUR & 28.500–29.000 \\
46 & AEROMOBILE & 13.200–13.360 & 94 & AMATEUR & 29.000–29.700 \\
47 & FIXED/MOBILE & 13.360–13.600 & 95 & FIXED/MOBILE & 29.700–30.000 \\
48 & BROADCAST & 13.600–13.800 & & & \\ \hline \end{tabular}
\end{table} 
Table 1: ITU HF frequency allocations. At early morning (06:00 LT), as the solar radiation increases, the MUF (that is, the critical frequency of the F2 layer multiplied by an MUF factor, which is a function of the link distance) increases, which encourages some of the users to migrate to the middle range of the HF spectrum (15-20 MHz), as shown in Figure 4b, to exploit the available spectrum. Figure 1: (**a**) Measurement system; (**b**) HE016 antenna. Figure 3: (**a**) Electric field strength measurements and (**b**) channels exceeding a threshold of 20 dB\({}_{\mathrm{\mu}}\)V/m for 5.060–5.480 MHz. Figure 2: Congestion measurement within an ITU allocation.