In this paper, we report a sequential-phase fed broadband circularly polarized array antenna loaded with an artificial magnetic conductor-reflecting surface. Our proposed antenna is a two-part group. The upper structure is a sequential-phase fed circular wide-slot antenna. The lower part is an artificial magnetic conductor structured reflective surface. The overall antenna size is 106 × 106 × 14.9 mm³, both adopting 1.6 mm thick FR4 material. The thickness of the air layer sandwiched between the antenna and the artificial magnetic conductor reflective surface is 14 mm. The antenna consists of four circular wide-slot antenna units with a sequential rotation technique. To broaden the axial ratio bandwidth, three L-shaped branches and four metal plates are attached to the circular wide-slot antenna unit and around the artificial magnetic conductor-reflecting surface, respectively. To verify the accuracy of the simulation, we fabricated the sample and then tested it in an anechoic chamber. The measured results demonstrate that the proposed broadband circularly polarized array antenna realizes an impedance bandwidth of 77.67% (2.74–6.22 GHz) and an axial ratio bandwidth of 65.16% (3.00–5.90 GHz) with a peak gain of 11.1 dBi. The design can be used in space-constrained environments, such as indoor and dense building areas.

Conventional metamaterial absorbers eliminate the transmitted electromagnetic wave by attaching the metal plate with the unidirectional absorption performance; these absorbers limit the practical applications to a large extent. In this paper, we present a broadband bi-directional metamaterial absorber by etching chip resistors on the resonators for expanding the bandwidth, and two orthogonal I-shaped structures are pasted on the both sides of the ultra-thin substrate (FR-4) instead of the metal plate for enhancing absorptance of the absorber. Simulated results show that absorptance of the designed absorber is larger than 0.9 in 1.43–2.51 GHz along the forward and backward directions under both TE and TM polarizations. Microwave experiments in the chamber are performed to verify the simulations, and the experimental results exhibit the excellent agreement with the simulations. Additionally, two I-shaped structures are orthogonally pasted on an ultrathin substrate, leading to the impedance-matching of both forward and backward directions, and the absorptance can be tailed dynamically via the middle layer of the substrate. The physics of the absorption are visualized by using a transmission line based on equivalent circuits. We claim that the designed bi-directional metamaterial absorber can be a good candidate for electromagnetic stealth and energy harvesting.