A Novel Integrated Switchable Absorber and Radiator

First, a novel integrated structure with selectable absorbing and radiation capabilities is proposed, which consists of periodic arrays of metallic three-loop nested structure printed on a thin grounded dielectric slab. Lumped resistors with different values are fixed on each side of all three loops, while PIN switches are optionally fixed parallel to the lumped resistors on the specific loop. When the switches are turned off , the parallel lumped resistors become operational, the present integrated structure acts lossy and performs broadband absorption function. When switches are turned on , those parallel lumped resistors are shorted, the corresponding loop structure can be regarded lossless, acting as a patch antenna. Second, equivalent circuit models of the present structure of absorber and radiator are developed and analyzed, respectively, to explain the working principle of the present structure. Finally, a $3 \times 3$ periodic array of metallic three-loop nested structure printed on an F4B dielectric slab has been designed, fabricated, and measured. Both simulated and measured results show that the proposed design can obtain a high absorptivity over a broad frequency band. Meanwhile, by changing the PIN switches’ state, the present structure can achieve good radiations at specific frequencies.