Antenna Height Slant to Vertical Converter
Converts a GNSS slant antenna height measurement to true vertical height using the antenna radius offset.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the slant height you taped from the ground mark to the antenna's slant measurement mark.
- Enter the antenna's slant radius from its data sheet.
- Add the vertical offset to the antenna reference point (ARP) if the data sheet gives one, then read the true vertical height.
How it works
A slant tape measures the sloping distance to a mark on the antenna's edge, so the true vertical height is √(slant² − radius²) by Pythagoras, using the antenna's slant radius.
You then add the vertical offset from that mark to the antenna reference point (ARP) so the height matches the point your GNSS processing expects.
Worked example
Slant 1.532 m, radius 0.0921 m. Vertical = √(1.532² − 0.0921²) ≈ 1.529 m, plus any ARP offset from the antenna calibration sheet.
Tips
- A wrong antenna height feeds straight into your ellipsoidal and orthometric heights — double-check the radius, offset and the mark you measured to.
Frequently asked questions
Why not just measure vertically?
A vertical tape to the antenna edge is awkward and easy to get wrong over a tripod. A slant measurement to a defined mark is repeatable; the geometry then converts it to the vertical height.
Where do the radius and offset come from?
From the antenna manufacturer's calibration/data sheet (or the IGS antenna tables). Using the wrong antenna model's values is a common source of a constant height error.
Is this official course material?
No. It is free study support mapped to surveying course levels — not official North Metropolitan TAFE content or advice. Always follow your lecturer and the official assessment brief, and check your own working.
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Cite this tool
Zerdly. (2026). Antenna Height Slant to Vertical Converter. Retrieved from https://www.zerdly.com/tools/antenna-height-slant-vertical-converter/
Length conversion table
How much one of each unit equals in the others — read each row as “1 [row unit] = …”. All values are exact conversions.
| 1 unit = | mm | cm | m | km | in | ft | yd | mi |
|---|---|---|---|---|---|---|---|---|
| 1 mm | 1 | 0.1 | 0.001 | 0.000001 | 0.03937 | 0.003281 | 0.001094 | 0.000001 |
| 1 cm | 10 | 1 | 0.01 | 0.00001 | 0.393701 | 0.032808 | 0.010936 | 0.000006 |
| 1 m | 1,000 | 100 | 1 | 0.001 | 39.370079 | 3.28084 | 1.093613 | 0.000621 |
| 1 km | 1,000,000 | 100,000 | 1,000 | 1 | 39,370.07874 | 3,280.839895 | 1,093.613298 | 0.621371 |
| 1 in | 25.4 | 2.54 | 0.0254 | 0.000025 | 1 | 0.083333 | 0.027778 | 0.000016 |
| 1 ft | 304.8 | 30.48 | 0.3048 | 0.000305 | 12 | 1 | 0.333333 | 0.000189 |
| 1 yd | 914.4 | 91.44 | 0.9144 | 0.000914 | 36 | 3 | 1 | 0.000568 |
| 1 mi | 1,609,344 | 160,934.4 | 1,609.344 | 1.609344 | 63,360 | 5,280 | 1,760 | 1 |
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.