Top 5 RF Line of Sight Calculators (And Why Desktop Tools Fail in the Field)
Compare the best RF Line of Sight and Fresnel zone calculators—including Ubiquiti airLink, HeyWhatThat, Radio Mobile, and native Android alternatives.
Setting up a reliable wireless link—whether it is a 915MHz Meshtastic node, a 5GHz WISP backhaul, or a 5.8GHz long-range FPV flight—always starts with the same fundamental question: Will the terrain block my signal?
For decades, radio engineers and hobbyists have relied on desktop web utilities to plot elevation profiles and check Fresnel zone clearance. Those tools work fine when you are sitting at a desk with a 27-inch monitor and a mouse.
The problem starts the moment you step outside.
Why Desktop Web Calculators Fail Out in the Field
When you are standing on a rooftop aligning a directional antenna, hiking a ridge to place an off-grid LoRa repeater, or scouting a mountain launch spot for an FPV flight, desktop-first web tools turn into a major bottleneck:
- Touchscreen Friction: Dragging tiny map pins on an unoptimized desktop webpage from a smartphone browser often results in accidental zooms, misplaced coordinates, and broken layouts.
- Heavy WebGL Battery Drain: Full 3D browser tools load massive map tiles and scripts that overheat mobile devices and drain battery fast when you are off-grid.
- Too Many Parameters for Quick Checks: Many legacy tools require you to configure accounts, antenna gain patterns, and cable loss tables before showing a simple elevation profile.
If you need fast answers outdoors, choosing the right tool for your environment makes all the difference. Here is how the top 5 RF Line of Sight (LOS) calculators compare today.
Quick Comparison: Top RF Line of Sight Tools
| Tool | Platform | Best Use Case | Mobile Field Usability |
|---|---|---|---|
| LinkSight | Native Android App | Fast field LOS, Meshtastic, FPV & WISP surveys | High (Built for touch & outdoor use) |
| Ubiquiti ISP Design Center | Web (Desktop-first) | Planning Ubiquiti-specific WISP links at a desk | Low (Heavy 3D interface on mobile) |
| HeyWhatThat | Web (Legacy UI) | 360-degree viewsheds & horizon panoramas | Low (1990s layout, hard to tap on phones) |
| Radio Mobile Online | Web / Windows | Deep ITM propagation modeling for repeaters | Low (Steep learning curve & desktop forms) |
| SCADACore LOS | Web | Quick desktop two-point elevation checks | Medium (Clean web page, not native) |
1. LinkSight (Best Native Android App for Field Use)
LinkSight was built from the ground up to solve the exact frustration of using desktop web calculators on a phone. Instead of wrapping a slow webpage, it runs as a native Android application designed for instant terrain profiling on the go.
- Strengths: Drop two pins smoothly on a native map and get instant Line of Sight and Fresnel zone clearance using global topographic data. It includes quick frequency presets (like 900MHz/915MHz for LoRa and 5.8GHz for FPV or WISP links) and lets you adjust antenna heights in seconds.
- Limitations: Currently focused on point-to-point path profiling rather than 360-degree coverage maps.
- Verdict: The go-to choice whenever you are away from your desk and need a fast, battery-friendly answer on your phone.
2. Ubiquiti ISP Design Center (Formerly airLink)
Ubiquiti’s free web planner is an industry staple for Wireless Internet Service Providers (WISPs).
- Strengths: It renders detailed terrain views and automatically calculates throughput estimates and link budgets for Ubiquiti hardware.
- Limitations: It is heavily tied to Ubiquiti’s product catalog and requires loading a heavy WebGL environment. Trying to adjust link endpoints on a mobile browser while standing on a client's roof is slow and frustrating.
- Verdict: Great for office planning if you exclusively deploy Ubiquiti gear, but impractical as a quick pocket utility.
3. HeyWhatThat
If you spend time in amateur radio, SOTA, or Meshtastic communities, you have seen screenshots from HeyWhatThat.
- Strengths: Its ability to compute 360-degree viewsheds (showing every mountain peak visible from a single coordinate) is legendary.
- Limitations: The user interface has barely changed since the late 1990s. Navigating small text links, zooming panes, and pinpointing exact ridge coordinates on a smartphone screen takes patience.
- Verdict: Unbeatable for desktop viewshed research at home, painful for spontaneous checks in the field.
4. Radio Mobile Online
Based on the Longley-Rice (Irregular Terrain Model) propagation algorithm, Radio Mobile is a powerhouse for serious RF engineering.
- Strengths: Accounts for deep radio parameters including ground conductivity, climate, polarization, and exact transceiver sensitivity.
- Limitations: High barrier to entry. Setting up a single link requires registering an account and filling out multiple technical menus before seeing a result.
- Verdict: Ideal for planning permanent high-power VHF/UHF repeaters from your PC, overkill for checking if a hill blocks your portable node.
5. SCADACore Line of Sight Calculator
SCADACore offers a free web-based RF Line of Sight utility geared toward industrial IoT and telemetry deployments.
- Strengths: Straightforward two-point calculation without forcing you to select proprietary hardware brands.
- Limitations: Still relies on a standard desktop web layout, requiring stable connectivity to reload map scripts and form inputs inside a mobile browser.
- Verdict: A solid bookmark for your laptop browser when you just want a quick two-pin elevation chart.
Which Calculator Should You Use?
The smartest workflow combines desktop planning with native mobile verification:
- At Home: Use desktop tools like HeyWhatThat or ISP Design Center on a large monitor for broad regional planning.
- In the Field: Use LinkSight on your Android phone to verify real-world coordinates on the spot, adjust antenna heights dynamically, and confirm your Fresnel zone clears every ridge before you deploy hardware or launch a flight.