This paper presents the design of a symmetrical unequal lumped-elements Wilkinson power divider with 5 output ports operating at center frequencyf_r=435 MHz, which will be used for the airborne DLR F-SAR system [1] to investigate multifrequency polarimetric SAR applications. Based on theoretical and simulated analysis an appropriate design has been developed regarding to the electrical system specifications like the high-power purposes. On the other hand, the mechanical layout is a major aspect for an airborne SAR system, hence it was very important to realize a very compact, cost efficiency and light weight design. A first in-house manufactured prototype was set up and the analysis of the measured parameters matches both the electrical and mechanical design goals very well, confirming the validity of the proposed design