In this letter, we develop a new Multiple‐Input Multiple‐Output (MIMO) antenna that has two independent signal feed‐points in a single antenna element. This antenna is composed of a cross‐coupled semi‐loop (CCSL) structure and an inverted‐F antenna (IFA) operating at 2.4–2.483 GHz and 5.15–5.85 GHz. The dual‐port structure is implemented by adding a CCSL antenna as the secondary radiator to the ground short of an IFA. To achieve isolation between the signal‐feeding ports of the antenna at the same operating frequency, a loop‐type coupling pattern is used to make the induced current flow orthogonal with respect to that of the other feeding port. The measured isolation performance between the feeding ports greater than 12 dB at 2.4 GHz and greater than15 dB at 5.5 GHz. We show that the proposed antenna has an Envelope Correlation Coefficient value as low as 0.3 at the 2.4 GHz band and as low as 0.1 at the 5.5 GHz band. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:930–934, 2017

A frequency-reconfigurable antenna based on aperture tuning using a coupled aperture structure on which a digital variable capacitor (DVC) is connected is presented. The coupled aperture structure is used to avoid electrical contact between the antenna radiator and the DVC in order to reduce antenna efficiency degradation due to ohmic losses at the DVC. The operating frequency is 700 MHz where the antenna efficiency is sensitive to the ohmic loss in the DVC. Analysis based on measurements and simulation confirm the benefits of using the coupled aperture structure over the conventional aperture tuning. It is shown that the coupled aperture plays a key role in reducing the impact of the equivalent series resistance of the DVC component on the antenna efficiency at 700 MHz.