I needed an antenna that would fit entirely within my backpack, along with radio, tuner, coax, battery, headphones and key. In other words, one pack with a complete portable station on my back.
In the past I had always carried a second pack with poles, guy lines and tent pegs to support a vertical antenna above ground (thereby requiring fewer radials or counterpoise wires). A simple vertical, mounted inches above ground on a spike would be lightweight and easily portable. The downside is the need for a system of radials which take longer to deploy and occupy a larger footprint.
After a little experimentation I came up with a design that is lightweight, stealthy, requires no guying and uses a system of 8 radials, each 13 feet long that is very quick to deploy in the field. It still occupies a circular footprint with a diameter of 26 feet, but that much space is usually available on a field outing.
Rapid Deployment Radials
There are 8 radial wires, organized into 4 pairs. Each pair is joined at one end with a ring terminal for connection to the antenna. To deploy each pair, a 13 foot long piece of cord is attached to the base of the antenna and used to mark the end point of a radial pair which is then pegged to the ground. The other end of the pair is then extended past the base of the antenna to a point directly opposite and pegged into place. The process is repeated four times to complete the radial field. The process takes only a couple of minutes.
The whip is an MFJ-1979 17-foot telescopic intended for 20m. I obtained an SWR of 1.3:1 on that band. A pleasant surprise was that the antenna was also tunable on 40m. I responded to SOTA and POTA calls and QSOd on both 20m and 40m with only 35 watts of power on CW. Conclusion: a very good antenna that meets all the design criteria.