Model formula calculator for RF attenuation over distance

[Wilson__]

Any advises for web page or Excel spread sheet or formula for calculating RF signal attenuation over distance in real world situation (not free space)? 

Antenna height in single-digit meters, distance of 'zero' to 2km, residential area (no high building), 800 to 900MHz. 

Many thanks.

[shabaz]

Some of the semiconductor manufacturers offer calculator tools, e.g. Silabs website has a downloadable spreadsheet with models for free range and office environment.

Matlab has capability too: https://uk.mathworks.com/help/comm/ref/propagationmodel.html
(not free, but low-ish cost for a home license). You can select quite a few propagation models. I've not used that function myself so I cannot comment.

However, you mention you're interested in 800-900 MHz, and part of that may be in an ISM band, so you can just try it out for real at an allowed frequency. I've done that in the past; simply get a couple of RF chip dev-boards, and modify the demo code to send packets (and display reception with even just an LED, it's not even essential to have a digit/text display), and just go for a walk with the other board, and see how far you get. That's very feasible at 868/915 MHz, and will give you a more realistic feel for what is possible with what antenna and location.