Purpose

AGTC (Antenna Gain / Temperature Calculator) is a numerical tool developed for the evaluation of antenna
G/T_A based on far-field radiation pattern data (FFTab).

First of all, create this FFTab file with EZNEC or 4nec2. Next use AGTC-JS file which will calculate the
G/T_A ratio of your antenna.
As always in radio work: the result is only as good as the data you put in.

No interpolation, no symmetry assumptions, no hidden processing: what you get is exactly what is contained in the pattern file — nothing more, nothing less.

This program is intended for amateur radio operators and experimenters. It remains subject to the usual limitations of numerical methods and input data quality.

Use it, question it, and verify it on the air whenever possible.

— AGTC-JS
Experimental tool for amateur radio
2026

History

See the References articles section below.
In 2016, we wrote the original AGTC_lite.bas program in QB64 Basic and published it in early 2017. Its latest version, still in QB64, is named AGTC_anyGTa_2lite_V2-00.bas. In January 2026, BG5TOX & BG5ATV ported this program to HTML/JavaScript.
This gave us the idea to also create this port, incorporating all the preliminary tests performed on the FFTab file, tests which were present in our original program.

How to distribute, modify, etc. this program?

You may distribute, remix, adapt, and build upon the material in any medium or format for noncommercial purposes only, and only so long as attribution is given to the creators.

These articles follow the principles described in the literature (notably DJ9BV, DUBUS 4/1987), using a full spherical integration of the antenna pattern combined with simplified sky and earth temperature models.

Disclaimer of Warranties

This software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement.

Limitation of Liability

In no event shall the author be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.

The user assumes full responsibility for the use of this software and for any results obtained.

Reference articles, written by F5FOD with DG7YBN

Part 1: An Antenna G/T calculator (AGTC_lite) without mathematical rotation calculations, DUBUS 1/2017
Part 2: An Antenna G/T calculator (AGTC and AGTC_fast) with mathematical rotation calculation, DUBUS 2/2017
Part 3: A brief history of the AGTC_lite/AGTC project and some additional references, DUBUS 3/2017
Part 4: Thirty years ago, DJ9BV was 100% correct in his antenna Effective Noise Temperatures (…) calculation article; an important consequence for AGTC_lite, DUBUS 4/2017