This is an upcoming project of mine. Due to space constrain I will only have space for a shortened 20 m dipol.
In an ideal case it will 10.7 m long. But for this antenna I have only about 6.2 m available. So the idea is to make a shortened dipol with coils. According to the info on the K7MEM page 6.2m is a little too short for an efficient antenna but I will give it a try... K7MEM has made a lot of interesting javascript web-based programs for calculating different electrical properties such as shortened antenna properties. When you have calculated the antenna you can as a next step calculate how to make the inductances needed! The excellent picture above is generated by the K7MEM antenna calculation page.