Design and development of a multiband loop antenna for cellular mobile handsets

This paper presents the results of the design and characterization of a loop antenna for mobile cellular handsets. Based on a typical smart phone antenna geometry, a bottom mounted off-ground meanderline loop antenna has been designed, which has the potential to cover the required bands of Long Term Evolution (LTE) US 700 MHz, Global System for Mobile communications (GSM) 824-960 MHz, Digital Communication System (DCS) 1710-1880 MHz, Personal Communication Services PCS 1850-1990 MHz, Universal Mobile Telecommunications System (UMTS) 1920-2170 MHz and LTE EU 2500. The carrier volume of 50*10*5mm³ and ground plane of length 100 mm is used. The carrier permittivity ε_r is 2.66 and loss tangent tanδ is 0.00629 @2.44 GHz. Copper is used as a metal part of the antenna having conductivity of 5.8e7 S/m and thickness of 0.1 mm. The antenna supports balanced and unbalanced modes for certain frequencies. It is highly efficient in terms of small volumetric size for a given bandwidth of operations. The antenna generates weak near field electric and magnetic fields complying with the standards for the Specific Absorption Rate (SAR) and Hearing Aid Compability (HAC). The impact of body effects on the radiation efficiency has been quantified. The measured results of the prototype are in good agreement with the simulated results.