I want to know the answer to the following question:
What can be added to allow for an antenna shorter than the needed height to produce desired results?
All the background I'm provided with is that "For example, at 30 MHz (10 m wavelength) a true resonant 1⁄4-wavelength monopole would be almost 2.5 meters long, and using an antenna only 1.5 meters tall would require the addition of a loading coil.". Is that enough to answer the question?