This paper describes the planar antenna which represents antenna array of rhombic slot radiators on the dielectric substrate, which are feed by field of traveling waves in the slot transmission line. The developed approach to determining the slowing factor allows to calculate the required length of the slot transmission line to provide common-mode excitation of the radiating elements of the antenna array. A physical model of the antenna array was created and experimentally investigated its electrodynamic characteristics — the radiation pattern and the directive gain in the frequency range. Experimentally investigated the slowing factor and the wave attenuation in the slot transmission line in the frequency range 2–4 GHz to select the optimal parameters of the slot transmission line construction. A comparative analysis of the results obtained by mathematical modeling and experimental research was done. The authors proposed the scheme of the antenna array feeding, providing the in-phase excitation of four slot rhombic radiators, so that the radiation pattern has a unidirectional character for a vertically polarized signal, there is an insignificant lateral radiation in the horizontal plane in the direction of the surface of the antenna array. Slot rhombic radiators can be used as the radiating elements of antenna arrays, which can be used as hidden antenna systems of mobile devices. The received crosspolarized radiating patterns indicate the possibility of applying such radiators as elements of interferometers.
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