Design of compact helical antenna at 200 MHz

The objective of this paper is to design a compact helical antenna at a frequency of 200 MHz, with prescribed volume constraints. The antenna has to have a reasonable gain (say 5 or 7 dB) and also fit in a cylindrical volume of about 25 cm in diameter with a length of about 1 m. The radiated fields will be circularly polarized. If we think of a standard helical antenna operating in an axial mode, the major diameter would be about 50 cm, and the spacing between turns would be about 30 cm, and the axial length for a 5 turn antenna would be about 1.5 m. These dimensions are excessive and ways to constrain the antenna dimensions without too much of a compromise in performance is desired.