## Statistical elevation-angle distribution

## Vaasa (Finland) to Western USA

## 1. All SSNs & all months

The following charts show how well the elevation angles of the given antennas (see Table 1 below) on the given amateur radio bands can cover the statistically measured elevation-angles that are needed for making radio contacts from Vaasa (Finland) to the given target area.

Method 25calculates all contributing propagation modes, i.e. not only the lowest angles are considered but also a great deal of higher elevation-angles. Method 25 is a forced ray-hop model, also for distances over 7,000 km where forward scattering starts to kick in. For distances over 10,000 km, VOACAP can sometimes badly under-predict the circuit propagation when this method is used.

Method 30calculates only one elevation angle for the Most Reliable Mode (per frequency), i.e. the propagation mode that VOACAP thinks is the most reliable for achieving the Required SNR of 24 dB/Hz, a threshold value that was used in the preparation of the elevation-angle database. Method 30 is typically a ray-hop model up to 7,000 km, beyond which it also starts to consider forward-scatter propagation mechanisms. This method always favours the lowest possible elevation-angle for the circuit.In the following presentation, the SSN values of 5, 25, 50 ,75, 100 and 150 as well as all months of the year have been considered in the elevation-angle distribution.

Table 1. Optimal antenna heights & take-off angles for H-pol antennas such as dipoles and Yagis Band h/AGL -3 dB Peak -3 dB 80M 95 m 6° 12° 18° 40M 60 m 5° 10° 15° 20M 52 m 3° 6° 9° 15M 42 m 2° 5° 7° 10M 35 m 2° 4° 6°

Band Method 25 Method 30 80M 40M 20M 15M 10M ## 2. SSN 25 & all months

In the following presentation, only the SSN value of 25 as well as all months of the year have been considered in the elevation-angle distribution. SSN 25 is the smoothed sunspot number predicted for the end of 2009.

Band Method 25 Method 30 80M 40M 20M 15M 10M