You're not going to be able to shrink the overall dimensions and still expect it to work. Bulky? Your only option is flimsier construction, which would lighten the load, but then it would be more likely to get damaged.
Yes this is a direction finding antenna, I am asking if anyone here built one, and experimented with different materials.Are you looking for a high gain antenna or a Radio Direction Finding antenna? The link provided is a direction finding antenna and not for general purpose use.