If you’ve been looking for a practical, free introduction to antennas, the US Marine Core Antenna Handbook (MCRP 8-10B.11, 2016) is a good place to start. The book is especially good for simple HF antennas that can be put up at home or in the field.
The PDF is 193 pages. The main section of text is 160 pages, with a very good 20 page glossary at the back.
If you enjoy learning about antennas from this handbook, your next step should be the ARRL Antenna Book. If you’re not ready to shell out $65 for the 1024 page 24th edition of that book, check your local library. Older editions are less comprehensive, but they still have lots of great info. My 12th edition from 1970 is still useful. Antenna physics has not changed over time, just our understanding of it.
Let’s go over some of the sections of the USMC Antenna Handbook to see the strong and weak points.
Radio Waves, Propagation, and Noise
These sections are very good, especially about HF propagation. It could cover VHF/UHF multipath a bit better. Repeaters are not mentioned. Those are common in amateur radio, but apparently not in the Marine Corps. Serious VHF/UHF amateurs dig into other kinds of propagation not covered here, like tropospheric ducting, meteor scatter, moonbounce, aircraft scatter, and so on. Those are advanced topics, so it is reasonable to not cover them here.
This is not my favorite section, but the mistakes here are very common in popular explanations of transmission lines. Unbalanced vs balanced is not a helpful way to think of transmission lines. All kinds of transmission lines carry a mix of differential (balanced) currents and common-mode (unbalanced) currents. Also, it talks about baluns as balanced-to-unbalanced transformers, but they are most useful as common-mode chokes. Still, this is a fairly standard introduction to the subject.
HF Antenna Selection
Very good section, with lots of ideas for how to actually get wire into the air for horizontal dipole or vertical ground plane antennas. You won’t find coverage of ham favorites like the G5RV, off-center fed dipole, Carolina windom, or even the end-fed half-wave. The antennas covered here are all simple and proven.
This chapter does discuss NVIS (near vertical incidence skywave) propagation, something that is fairly recent in amateur practice. The first QST article on NVIS was in 1995 and it has only become popular in the last 10-15 years.
There is one interesting antenna that is new to me, the vertical half-rhombic. This requires a fair amount of space, up to 1000 feet, but is unidirectional and only needs one support.
VHF and UHF Antenna Selection
This section is a bit less useful because it relies on specific military antennas instead of describing types of antennas. For example, the OE-254 is a bow-tie vertical dipole, a low-Q, high-bandwidth antenna, but they just call it an OE-254.
Military VHF/UHF antennas need to work over a wide range of frequencies, but amateurs can use antennas optimized for the small number of bands that we are allowed to use. The most common single- and dual-band ham antennas are not described here, designs like collinear phased verticals, Yagi-Uda beams, haloes, Moxon beams, J-poles, and so on.
Field Repair and Expedients
Read this before ARRL Field Day! Here are some suggestions of what to do when an antenna insulator breaks.
Some really good advice on choosing antenna sites, useful even if you are just putting up one antenna. I don’t think I’ve seen this covered in detail in any other book. A lot of hams will end up with at least two antennas, one for HF and one for VHF/UHF, so this is a worthwhile read. We won’t normally be considering security measures like barbed wire and automatic weapons, so you can skip to the Technical Considerations section.
And that’s all! Enjoy learning about antennas.