  The Hydrogen Epoch of Reionization Array (HERA) is a new powerful
radio-telescope, dedicated to the study of the early universe. Its main goal is
to characterise the period of the universe where the first galaxies and stars
started to form, by studying the evolution of the 21-cm emission signal from
neutral hydrogen, during the Epoch of Reionization. In this article, we present
an electromagnetic and electrical co-simulation of the antenna performed with
CST. We focus our analysis on the characterisation of the chromatic effects
caused by the antenna, in particular multiple reflections of the received
signal between the feed and the dish. These reflections can have an important
impact on the scientific results, and it is crucial to keep them as low as
possible. Therefore, we are currently developing a matching circuit which aims
to improve the impedance matching between the feed and the front end.
