[Antennas] Coaxial Colinears

[W0OXJ]

Does anyone have experience with installing these antennas in PVC tubing?I understand this will lower the design frequency and the sections of the antenna will need to be shortened.I have heard 5 percent shorter and have heard 19 percent shorter.

Does anyone have definitive info on this subject?Has anyone actually measured a commercial antenna and calculated the length of the half wave sections relative to free space as well as installed space?

Thanks for the info.

73,
Bob
W0OXJ