This is a center-loaded, 1/4-wave vertical that I made for 40-meter pedestrian mobile operating. The antenna starts with 9.5 feet of 20-ga stranded wire at the top. This connects to a coil made with 15 turns of 18-ga wire wrapped around 2-inch (thin-wall) PVC tubing and, finally, a 10-foot length of 20-ga wire ending with a banana plug. The antenna plugs into a small mint box which allows me to add a counterpoise wire and coax with a BNC connector. 

Gary, N5ANF and I tested the antenna on March 12, 2005 from an 8,000-foot mountain top here in Colorado. The antenna was supported by a 20-foot fiberglass fishing pole. That in turn was placed on a 5-foot piece of PVC pipe and lashed to the tailgate of my pickup. With five watts from my FT-817, we worked stations on 40-meters from Oklahoma and Kansas to as far away as New York and Georgia, with a 56 report of my QRP signal from the GA station.