Abstract-Current phones include more metal than earlier, which deteriorates the performance of antennas. This paper presents the first complete antenna set designed for a modern handset with a full metal back cover. 4G, Wi-Fi, and GPS antennas are integrated into the metallic side frame of the device in a realistic model. The designed antennas are either capacitive coupling elements with reactive loads or slot antennas. Fixed matching circuits are used to improve total efficiency. The passive implementation enables the use of carrier aggregation (CA) to increase the data rates, and includes also the multipleinput multiple-output (MIMO) operation for 4G and Wi-Fi. The designed antennas cover frequency bands 704-960 MHz, 1.56-1.61 GHz, 1.71-2.69 GHz, 2.4-2.484 GHz, and 5.15-5.875 GHz, producing in measurements a good agreement with simulation results.
This article describes a dual-polarized end-fire antenna array for millimeter-wave frequencies. The antenna consists of a chain-slot-shaped pattern on a mobile phone metal frame. The antenna is fed using a transmission line, which would cause only a negligible capacitive loading of the sub-6 GHz antenna realized on the same metal frame and, therefore, would not significantly degrade its perfomance. This makes colocating the sub-6 GHz and mm-wave antennas in the same, shared volume possible. Measurements indicate that a 4-element array placed within a mobile phone provides a realized gain between 8 and 12.6 dBi for both polarizations across the entire band from 24.5 to 29.5 GHz. The total efficiency of a single element is better than −2 and −3 dB for the whole band for horizontal and vertical polarizations, respectively.
The co-existence of millimeter-wave (mm-wave) and sub-6 GHz antennas in a smartphone presents many performance-limiting aspects. When both antennas are attached to the metal frame, the feed lines of the mm-wave antennas might short-circuit the sub-6 GHz antennas, and thus, may significantly affect their performance. This paper presents a method to design feed lines that function as transmission lines at mm-wave frequencies but correspond to open circuits at sub-6 GHz. This study determines, in theory, the smallest achievable capacitive loading with different line types and experimentally validates the approach. The capacitive loading due to the feed line is small enough to maintain the sub-6 GHz performance. At the mm-wave band, the insertion loss of the line is 1 dB with a measured reflection coefficient below −10 dB. The introduced common-mode capacitive load of the feed line on the sub-6 GHz antennas corresponds to 0.19 pF capacitance.
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