For the caravan I was looking for a simple not to big dual band antenna for 2m and 70cm. And the materials should not be difficult to get. I found this design on internet. The original design is from DL4KCJ en is used at the DARES (Dutch Amateur Radio Emergency Serves). It's called the Popovic-antenna. The antenna is a quarter wave for 2m and a 5/6 for 70cm. I made this antenna with different materials and works great. The SWR on both bands is below 1:1.2.
I want to use materials which you can buy with the do-it-self store. The only thing I bought at a radio market is the plastic cabinets. The pictures below show more than words can say. It's an easy to make antenna and an easy to transport and setup.