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In this paper, an asymmetric sinusoidal modulated substrate integrated waveguide‐spoof surface plasmon polariton (SIW‐SSPP) leaky‐wave antenna with open stopband suppressed is proposed. The SSPP transmission line can covert the guided waves to the leaky‐wave radiations with frequency‐scanning properties due to the sinusoidal modulation. Using asymmetric model is an effective method to restrain the open stopband. The asymmetric radiating element with π/2 phase difference between the upper and lower sides of the top surface is introduced in the antenna to realize zero‐crossing beam scanning and unidirectional radiation characteristic. In the operating band of 12.6 to 13.7 GHz, the measured scanning angle of the fabricated antenna is from −14° to +34°. The gain is above 10.1 dBi and the radiation efficiency is basically above 50% over the operating band. Although the way of eliminate the open stopband has been proposed, this is the first time it is used in SIW‐SSPP antenna design. It has potential applications in radar and wireless communication systems for simple structure, low‐profile, zero‐crossing beam scanning, and unidirectional radiation performance. [ABSTRACT FROM AUTHOR]

Dynamic metasurface antennas (DMAs) and dynamic antenna arrays (DAAs) are emerging concepts in low-profile antenna design, providing alternative structures with lower circuit complexity and power requirements for radar and communication systems. However, dynamic antennas are prone to significant grating lobe and beam fixation problems due to their discrete amplitude and phase control. The reasons behind these issues are explored through mathematical and simulation analysis of three specific cases, and solutions are subsequently proposed and partially experimentally verified. [ABSTRACT FROM AUTHOR]

Uniform circular array (UCA) is a pioneering approach to generate radio twisted beams carrying orbital angular momentum (OAM). However, faulty antenna elements in a UCA could render the array into an imperfect UCA (IUCA), consequently creating distortion for OAM-based communication or radar systems. To analyze the effects of an IUCA on generating OAM, elementary wave function and wave transformation are derived to obtain field equations of a general circular array. Further derivation of IUCA shows that the field of an IUCA is a superposition of OAM modes, which is caused by polluted orthogonalities of OAM modes. To achieve pure OAM modes, the orthogonal matching pursuit algorithm, the convex optimization tool, and the analytical solution are employed to design a feeding network to retrieve the orthogonal property at the cost of strong gain loss. Then, the reduced constraints method is proposed for the IUCA to achieve high-purity and low-loss OAM mode. Finally, four circular arrays with different shapes are explored for limited installation space to generate twisted beams. [ABSTRACT FROM AUTHOR]