Arrival angles

Robert A. Wilson n6tv at vnet.IBM.COM
Fri Apr 2 23:46:09 EST 1993

About a week ago K3NA asked if there were any propagation tools such
as IONSOUND that calculate arrival angles.  Well, I haven't used
IONSOUND, but MiniProp does this (even hour by hour, band by band).
If you don't have MiniProp, just type SH/MUF <prefix> on any
PacketCluster node and it will display the theoretical radiation
angle.  Both MiniProp and PacketCluster seem agree on the "dominant"
radiation angle, so I guess they both agree on the height of the

Given station A's QTH and Station B's QTH (Latitude/Longitude), and
assuming propagation off the F-layer only, the formula for calculating
the radiation angle is:


One thing that surprises me is that MiniProp shows, say, the two
F-hop path has radiation angle r on 10 meters and exactly the same
angle r for the two F-hop path on 80 meters.  Is this correct?  Do
both signals reflect off the F-layer at nearly the same altitude?

Bob, N6TV

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