With no permanent outdoor antenna setup, most of my operating is done portable — handheld yagi, FT-818ND, phone running a pass predictor, trying to juggle all three while actually making contacts. The workflow worked but it was clunky, and none of the existing tools were quite designed for the way I operate.
So I built one.
Ham Sat Tracker is a free web-based satellite pass predictor specifically for amateur radio operators. No app to install — it runs entirely in the browser, works on your phone, and is designed to give you everything you need for a pass in one place.
What It Does
Enter your Maidenhead grid square (or lat/lon coordinates) and it shows you every upcoming satellite pass with:
- AOS, TCA, and LOS times with azimuth at each point
- Doppler-corrected uplink and downlink frequencies at AOS, TCA, and LOS — so you know exactly where to start and where you’ll end up without doing any mental arithmetic mid-pass
- Maximum elevation for each pass so you can judge whether it’s worth setting up for
- CTCSS tones pre-filled where required (SO-50, ISS)
- A skyview polar plot showing the satellite’s track across your sky
- Operating notes for satellites with special requirements
The free tier covers SO-50, AO-91, ISS, FO-29, and RS-44 — the five most reliably active birds right now.
AntTrack — Antenna Pointing on the Phone
The part I’m most pleased with is AntTrack, a real-time antenna pointing tool built into the same app. It uses the phone’s compass and tilt sensor to show you azimuth and elevation guidance during the pass. For portable handheld yagi work, you hold the phone alongside the boom and AntTrack tells you where to point.
The Pro version adds one-tap pass handoff — tap “Track This Pass” on any pass card and AntTrack opens pre-loaded with all the pass data. AOS azimuth, max elevation, LOS azimuth, duration — all handed off automatically so you can focus on operating rather than data entry.
Built for Portable and Offline Use
One thing that was important to me was making it work in the field without cell service. TLE orbital data is cached locally after each successful fetch, so the predictor works even when you’re somewhere without a data connection. The app shows you how old the cached data is and warns if it’s getting stale. The practical workflow: update TLEs before you leave home, and you’re covered for several days.
The Live Map
A recent addition is a live map view for each pass — tap the map button on any pass card and you get a real-time view of the satellite moving across a world map, with your location marked, the satellite’s signal footprint shown as a circle, and a ground track projected forward. Useful for visualizing which other operators might be in range during the same pass.
How It Was Built
This project was built almost entirely using claude.ai — the same workflow I’ve been using for the e-paper projects on this site. I described what I wanted, fed errors back in for debugging, and iterated from there. The satellite propagation uses the satellite.js library for SGP4/SDP4 orbital mechanics, TLE data comes from CelesTrak via a server-side proxy, and the live map uses Leaflet with OpenStreetMap tiles.
The whole tracker runs client-side in JavaScript — no backend required for the predictions. AntTrack uses the Web Sensors API for compass and accelerometer access, which on modern phones works well enough for practical antenna pointing.
Try It
hamsattracker.com — enter your grid square and see what’s coming over your horizon.
It’s in public beta right now with all Pro features unlocked for everyone. When the beta ends, Pro will be a one-time $9.99 purchase covering the extended satellite list, 7-day lookahead, and date picker for planning ahead.
Feedback is welcome — there’s a form on the site, or catch me on the satellites. Listen for VE3AKK on SO-50 and RS-44.
73 de VE3AKK