Abstract

In a radio link two different or identical antennas are used each one performing a different role. For electromagnetic compatibility activities the receiving antenna factor is of paramount importance in order to measure the incoming spurious power density or electric field of any electrical or electronic device. Calculations as well measurements are performed to achieve this task using traditional equations and antenna software to get quick and simple results. Power transmission loss (Friis Equation) is only valid in free space as a general belief but in this paper it is proven that this principle is valid also for radio links over perfect ground [16], [17]. This statement permits the exclusion of any artificial factor to achieve the radio link power budget and power reciprocity principle [12], [21]. This fact takes into account the lack of losses in the natural space between both antennas as well in the perfect ground plane. At the same time, over perfect ground the total EM energy is travelling in a straight line connecting the transmitting (Tx) antenna radiation center and the center of the receiving (Rx) antenna, exactly like a radio link in free space, [16]. In order to improve the antenna factor calculation and calibration the procedure analizes all the parameters at any height of the Rx antenna for a fixed height of the Tx antenna at not only the maximum radiation over perfect flat ground plane. Result is achieved by a metallic ground plane where the conductivity is higher than 107S/m, so the reflexion coefficient module is exactly one.