Measuring the near-field emitted by an antenna is essential for diagnosing its proper functioning and identifying any manufacturing defects. Unlike scanning systems that incrementally move a point sensor, electromagnetic (EM) field thermography enables rapid mapping of a surface in just a few seconds. Developed at ONERA under the name EMIR, infrared (IR) thermography involves heating a thin film with EM radiation. An IR camera measures this heating, which is proportional to the EM power density, thereby revealing the field amplitude. More recently, a new thermography technique derived from EMIR has been introduced. This method involves coating the thin film with a fluorophore. The fluorescence intensity, which depends on temperature and thus on the field, allows for mapping of the EM field using a simple optical camera. Following a brief introduction to this method, we present its application to the measurement of a fractal antenna, which has also been numerically simulated.