Wideband Patch Antenna Using Multiple Parasitic Patches and Its Array Application With Mutual Coupling Reduction

A dual-layer patch antenna using multiple parasitic patches for the bandwidth enhancement is presented. Two additional resonances can be obtained with the help of the parasitic patches of the antenna. Consequently, a wide impedance bandwidth of 17% (<inline-formula> <tex-math notation="LaTeX">$\vert \text{S}_{\mathbf {11}}\vert <-10$ </tex-math></inline-formula> dB) can be achieved. Then, without the increase of the antenna array footprint, the combinations of two decoupling techniques (i.e., metalized via walls and short-circuited stepped-impedance structures as the neutralized networks) are adopted for mutual coupling reduction when the antenna element is extended to <inline-formula> <tex-math notation="LaTeX">$2\times1$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$2\times2$ </tex-math></inline-formula>, and even <inline-formula> <tex-math notation="LaTeX">$4\times4$ </tex-math></inline-formula> array applications. To validate the design idea, a <inline-formula> <tex-math notation="LaTeX">$2\times2$ </tex-math></inline-formula> antenna array is fabricated and tested, whose measured isolations between any two feeding ports are better than 28 dB within the frequency range of 3–4 GHz. The measured peak gain fluctuates from 12.6 to 13.6 dBi within the 10-dB impedance band of 3.35–3.95 GHz, and the cross-polarization levels in both the E- and H-planes are lower than −38 dB at the boresight direction.