The Isotron is not suitable for standard broadcast use as it will not meet minimum radiation standards. You CAN get away with it under an STA for temporary/emergency use, because all you need to do is radiate SOME type of signal to maintain on-air presence. I have one station using one now under those circumstances, but that is the only way one is "legal" on AM. As someone said, you can't cheat physics, but you can manipulate it sometimes. The folded unipole is a great antenna for many applications, and can be utilized to great capability in many cases. It can be used on a shorter than normal tower, and made even shorter by top loading, and still radiate to minimum FCC standards. The counterpoise is the key to making minimum, and that can be done with an elevated counterpoise. I am one of the leading consultants on both unipoles and elevated counterpoise, and have built several stations using both. I have recently developed a new technique of shortening the physical length of the radials to half what they would normally be, but still maintaining a full 90 degrees electrical length, so that drops the land use area by 50%. And if the station is non-directional, only four radials are needed to satisfy the FCC. On directionals they really want to see six. While I am always searching for the "fairy dust" that can make an AM antenna perform in the minimum amount of physical space, I (nor anyone in the past 100 years) have yet to find that magic key. But I have found the best hacks available, and they work and are FCC accepted. See the linked Radio World article.