This document describes a planning tool, EWPlan, developed within the Future Electronic Warfare Duel Simulation project. The planning tool's purpose is to show the influence of electronic warfare systems on sensors, radio systems and weapons. As electronic warfare is in focus, a planning tool must offer support for complex situations with interactions between sensors and other objects positioned in a terrain model. Therefore, a planning tool needs to be computerized and rather sophisticated; simply drawing on a map will not suffice. The planning tool EWPlan is the testing ground for ideas that can become operational in the future. With the plugin-based architecture, new modules are easily added to the planning tool. The coverage diagram module of EWPlan offers ways of showing different types of coverage diagrams as area markings on a map. These diagrams can be used e.g. for showing what area is covered by a certain sensor or where a jammer might be placed to get the desired effect on a sensor. All system models are generic and only turn secret after secret information has been entered into the parameters. Coverage diagrams may help in e.g. minimizing the area where your platforms risk detection, deciding the route to take to new locations and deciding where to place your sensors to increase your chances of detecting the enemy. The diagrams can also be used to plan movement and positioning to achieve better chances of detecting the enemy.