Identification of antenna parameters for calculation
Probably these dimensions are used to calculate the inductance by an approximation formular.

Wheeler's formular is likely used as it's often referenced when searching for such a respective approximation formular.



Then \$b\$ is:



And for \$h\$ you can think of printing that picture several times and placing the sheets one onto the other.



Here are also links of two sites applying wheeler's formular with isometric view pictures:

http://www.rfcafe.com Multi-Layer Air-Core Inductance


\$b \, @rfcafe \$ is \$h \, @your\,  picture\$
\$c \, @rfcafe \$ is \$b \, @your \, picture\$


www.allaboutcircuits.com


\$l \, (length of coil) \, @allaboutcircuits \$ is \$h \, @your\,  picture\$
\$c \, (thickness of coil)\, @allaboutcircuits \$ is \$b \, @your \, picture\$