**Carlos Camacho-Gomez, Rocio Sanchez-Montero \*, Diego Martínez-Villanueva, Pablo-Luís López-Espí and Sancho Salcedo-Sanz**

Department of Signal Processing and Communications, Escuela Politécnica Superior, Universidad de Alcalá, Campus Universitario, Ctra. de Madrid a Barcelona km 33.600, 28805 Alcalá de Henares, Spain; carlos.camacho@uah.es (C.C.-G.); diego.martinezv@edu.uah.es (D.M.-V.); pablo.lopez@uah.es (P.-L.L.-E.); sancho.salcedo@uah.es (S.S.-S.)

**\*** Correspondence: rocio.sanchez@uah.es; Tel.: +34-91-8856660

Received: 17 January 2020; Accepted: 7 February 2020; Published: 9 February 2020

**Featured Application: A novel textile U-shaped with concentric annular slot antenna prototype for LTE and 5G services has been described. In the ground plane, a meander slot has been introduced to reduce the antenna dimensions. A new multi-method metaheuristic algorithm, the Coral Reefs Optimization with Substrate Layer CRO-SL, has been used to optimize the antenna parameters and improve its performance in the frequency bands of interest.**

**Abstract:** A textile multi-band antenna for LTE and 5G communication services, composed by a rectangular microstrip patch, two concentric annular slots and a U-Shaped slot, is considered in this paper. In the ground plane, three sleeved meanders have been introduced to modify the surface current distribution, leading to a bandwidth improvement. The U-Shaped slot, the dual circular slots, and the meanders shape have been optimized by means of the Coral Reefs Optimization with Substrate Layer algorithm (CRO-SL). This population-based meta-heuristic approach is a kind of ensemble algorithm for optimization (multi-method), in which different search operators are considered within the algorithm. We show that the CRO-SL is able to obtain a robust multi-band textile antenna, including LTE and 5G frequency bands. For the optimization process, the CRO-SL is guided by means of a fitness function obtained after the antenna simulation by a specific simulation software for electromagnetic analysis in the high frequency range.

**Keywords:** antenna design; constrained optimization problems; coral reefs optimization algorithm; meta-heuristics
