The J-Pole
I am really happy with the J-pole-style antenna, especially when it comes to fixed operating positions. This January, I was providing race support for a half marathon in my hometown. We used golf carts to patrol the course and provide SAG (Support and Gear) services to runners in need. The course can be covered using an HT, but there are some parts of the course that the rubber duck antenna just doesn't have the reach that a good external antenna would have.
The problem with a golf cart is the lack of flat metal surfaces to provide a good ground plane for antenna mounts. The antennas you see on vehicles use the metal of the car as part of the antenna. The nice thing about J-Poles is that they are self-contained antennas that don't have the ground plane (metal) requirement.
I have been using an Ed Fong J-pole for my golf cart to support local races. You can see how long it is.
It's been a good antenna for extending the range of my HT while operating mobile. There are locations in the city where a standard HT antenna has trouble getting into the local repeater due to terrain. This J-pole setup extends the reach of my 5W HT.
Using the Rotating Arm Kit, you can build this for 2M and 6M J-pole configurations
2M J-pole - red-side length: 43 3/4 in - black-side length: 14 5/8 in
6M J-pole - red-side length: 74 13/32 in - black-side length: 42 21/64 in