My Extra Class License Manual published by the American Radio Relay League (2011) is an excellent tool for either referencing a topic or reviewing a topic. Admittedly, I memorized answers in order to pass the Extra Class examination, and now; I'm challenging my personal competency and endeavoring to a level of functional understanding.
I reviewed antenna gain, isotropic radiator, and directional antennas found in Chapter 9, pages 9-2 through 9-4, authored by Ward Silver in the license published by the American Radio Relay League.
What is gain? Does it mean more effective radiated power at the antenna? Is this another #hamr myth where one cheats both physics and the laws of the natural, observable world?
Not so according to Silver, where an isotropic radiator is considered theoretical not a real antenna, and it radiates equally well in all directions (2011). An isotropic is a construct from which all other antenna systems are referenced against.
Why the advantage of directional antennas over that of verticals or dipoles? Can this antenna cheat both physics and the universe? Silver stated such antennas concentrate their energy typically in one direction (2011). Additionally, the author continued, that such concentrated radio energy is referenced as forward direction known as major lobe. Furthermore, this is not a theoretically perfect system like an isotropic, instead some of that energy radiates from the back often times referenced as minor lobe according to Silver (2011).
Let's synergize that is forward direction is major lobe; at the back of a directional antenna is minor lobe; and an isotropic is a theoretical reference antenna. What about the gaps between major and minor lobes? According to Silver (2011), the gaps between lobes, are typically referenced as nulls.
The advantage of a directional antenna, according to Silver (2011) over verticals or dipoles, is a function of concentrating radio energy in a forward direction while reducing radiation off the side and back.
What about cheating physics and the universe? Does antenna gain actually mean more effective radiated power?
Silver explained gain as a ratio typically referenced as a decibel. I recommend reading his definition on page 9-3 located in Chapter 9 of the manual. On the other hand, a normalized directional antenna supposedly has 6 decibels of 'gain' not power over that of a comparison dipole. The 'gain' that is four times louder (6 decibels) than a comparison dipole is a function of concentrated radio energy in one direction and is an energy trade off from that of either the back or side (Silver, 2011).
Furthermore, returning to a discussion about soil permeability and ground reflections, Silver stated that nearby reflecting surfaces can dramatically influence antenna gain (2011). The effect may increase or decrease the 'gain' of one's system.
Overall, the term 'gain' does not cheat physics, the laws of nature, or the universe rather it is a function of concentrated radio energy in the forward direction at the expense of back and side efficiencies. Likewise, an isotropic antenna is not a real antenna, instead it is a theoretical antenna, as a quantitative measure in decibels radiating equally in all directions.
Life is high frequency.