An electromagnetic transmitter arrangement includes an antenna line array or subarray defining at least first and second ends, and including first, second, third, fourth, and fifth antenna elements, arranged with the first antenna element at the first end, the fifth element at the second end, the third element at the center, the second element between the first and third elements, and the fourth element between the third and fifth elements. Multiple (N) corresponding radio frequency sources are provided, each source communicating with a respective antenna element along a given radio-frequency signal path extending from the given signal source to the given antenna element, and where a first signal source generates signals at frequency f0, and each of the N−1 additional sources generate signals at frequencies of f0±(N−1)Δf, where N is an integer greater than or equal to 5.