the present invention relates to a portable directional antenna which is equipped with a camera which is integrated into the housing of the directional antenna . in addition to the conventional documentation of the position - finding information , this integrated , installed camera makes it possible , by means of the directional antenna function , to also optically document the surroundings of the interference source with a variable level of detail , for example by way long - range or short - range capture . by way of the optical additional information thus obtained , the present invention provides a simple , but nonetheless very effective , enhanced documentation option for interference sources and the surroundings thereof . thus , during the search for radio - frequency interferences , no separate camera for capturing image information has to be brought along , and this increases the comfort for a user . the present invention further relates to a portable measurement arrangement and to a method for measuring an electromagnetic signal emitted by a source .