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It is difficult to feed a 3 m monopole from the top, but there are things that can be done to overcome some of the problems related to mounting the transmitter at the level if the earth.
It has already been mentioned on another thread in this Forum that the area where the monopole is to be mounted could be built up slightly so that it forms a small mound that avoids flooding at the base of the antenna.
At one time, I had unintentionally built a mound in my yard by having a load of topsoil delivered, but not using all of it. When the topsoil was delivered, the dirt was far too loose for installing an antenna; but after several months, the mound became firm, and grass grew on it. Nobody would want to wait long enough for the mound to form naturally, so the mound would have to be packed down.
Another solution is to construct a grounded dipole antenna by installing the transmitter at the center of the 3 m monopole, and grouning the bottom end of this center-fed monopole. This arrangement has both advantages and diadvantages compared to a base-fed monopole. The principal advantage is that the radiation resistance is roughly doubled. Another advantage is that, because the monopole is fed at the center, the maximum RF current concentration is at the center, and not at the ground. This reduces ground loss. The principal disadvantage is that the capacitive reactance at the feed point is increased significantly (by about 75 %). Overall, the grounded dipole should have a small advantage over the base-fed monopole.