A GP antenna is an unbalanced antenna. Let's assume we view the antenna system as a DC circuit. The center pin of the radio's antenna port is positive, and the current flows out from here along the 50-3 conductor to the base of the GP antenna, then to the extendable antenna where it is transmitted.
Then, this circuit needs to form a loop. It will automatically find the path with the smallest resistance, from your GP antenna base's ground connection, through the 50-3 shielded cable, and back to the threaded hole on the radio antenna (which acts as the negative terminal).
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Therefore, the "grounding" of a GP antenna and its electrical grounding in electrical engineering have different meanings. In reality, it provides the "current" with the most ideal path back to the radio station. This allows for optimal impedance, radiation direction, and radiation efficiency.
The first method is completely impractical because it requires laying the ground plane on the surface. Generally, the standard practice involves laying a "ten" or "eight" shaped ground plane that is approximately the same length as the antenna (1/4 wavelength, and also needs to consider the reduction factor).Ground network"One approach involves treating the grounding as a protective ground. In this case, the current still relies on the ground, or more accurately, the concrete, to flow back and forth. As you can imagine, the antenna would be unusable in this situation."
Method 3: I actually tried this, using the MA-01 antenna mounted on the air conditioner's outdoor unit. The ground wire was directly connected to the outdoor unit, and the outdoor unit was connected to a protective ground wire. This effectively created a ground network for the entire building. In practice, the VSWR reached 1.0. However, due to the inherent characteristics of the MA-01 antenna (a super-gain antenna), its transmission and reception performance is not reliable. Nevertheless, the VSWR did reach 1.0.
Method two should be similar to method three, but I'm not very familiar with electrical work. The public grounding in method three should involve a "second-level grounding" at the bottom of the building, and then a working ground connection at the neutral point of the transformer. In other words, this grounding system is connected to the earth at the bottom of the building, and also connected to the neutral point of the transformer.
According to Method 2, the grounding for lightning protection should simply have been performed at the bottom of the building.
In summary, whether using Method Two, Method Three, or laying a "ten" and "eight" grid on the ground, you need to adjust the antenna length or the grid's length based on the real-time measured standing wave ratio.
If the ground wave remains unchanged, the frequency of the minimum standing wave must be lower than the frequency you are using. In this case, slightly shorten the antenna, or vice versa. This will ensure that the valley of the standing wave falls on the desired frequency.
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