A low profile (3.5 mm) dual-band operation laptop antenna designed for Wi-Fi 6E (2.4/5/6 GHz) bands is proposed. The proposed antenna is a double-slit loaded modified inverted-L antenna (ILA) structure that can excite multi-frequency mode, allowing it to fully cover the desired 5 GHz and 6 GHz bands (5150–7125 MHz). To further cover the 2.4 GHz band (2400–2485 MHz), a C-shaped coupling strip is further printed behind the modified ILA. Besides exhibiting a small planar size of only 22.3 mm × 3.5 mm that allows it to be applied in a narrow screen bezel laptop, the proposed antenna can still yield desirable measured 10-dB bandwidths of 2.4–2.485 GHz and 4.74–7.26 GHz, with good antenna efficiency of more than 40% and 61%, respectively.

A very-low-profile, two-antenna system formed by combining two identical monopole antennas with a decoupling inductor is presented. The two-monopole design was capable of operating in the 2.4 GHz (2400-2484 MHz), 5.2 GHz (5150-5350 MHz), and 5.8 GHz (5725-5825 MHz) wireless local area network bands and yet merely occupied a small size of 5 mm × 42 mm (about 0.04λ × 0.33λ at 2.4 GHz). The two antennas symmetrically facing each other were closely packed with 1 mm spacing and required almost no separation distance. An inductor connecting the open ends of the two monopoles was employed to reduce the mutual coupling in the 2.4 GHz band. Over the 5.2/5.8 GHz bands was good isolation achieved by the devised arrangement of the antenna current nulls of higher order resonance. Owing to its low height of 5 mm, the two antennas can fit in the current narrow bezel of the notebook display.

This paper proposes an eight-band long-term evolution (LTE)/wireless wide area network (WWAN) antenna design. The proposed antenna is 60 ×7 mm ² in size, and covered all dual broadband operations at 698-960 MHz and 1710-2690 MHz in the LTE/WWAN bands of LTE700/GSM850/DCS/PCS/1900/UMTS/LTE2300/2500. The proposed antenna is a monopole antenna comprising strip 1, strip 2, and the shorting strip. The space used to allocate the antenna and the metal components surrounding the antenna (e.g., the ground plane and the metal frame) was incorporated into the design. The resonant modes of the antenna are excited, as well as those of the slot used to allocate the antenna. The proposed antenna is characterized by seamless integration with the surrounding metal components and its wide operating bandwidths in a small size with excellent antenna efficiency. The antenna efficiency of the proposed design ranged 51%-72% at low frequencies and 50%-67% at high frequencies, which complied with the basic antenna efficiency demand of 50%.

This paper presents a compact dual-band four-element multiple-input multiple-output (MIMO) antenna system for the fifth-generation (5G) laptops with a large display-to-body ratio. The four antenna elements, each being a three-dimensional inverted-F antenna (IFA) of the same structure and size, are constructed on the same T-cross-sectioned substrate, the vertical part of which is embedded in the 1 × 64 mm2 clearance area created from the upper edge of the display ground plane. They are configured into two dual-antenna units. Within each unit, the two IFAs are arranged to be skew-symmetric with respect to the display ground plane, and their short-circuit points are brought close to each other to achieve the so-called short-circuit decoupling. In addition, the two units are mirror imaged of each other with a small gap in between and are connected by two decoupling chip inductors to form a high-isolation four-element MIMO antenna system. In the operating bands of 3300–3600 and 4800–5000 MHz required by 5G, the measured isolation is larger than 10 dB, and the measured antenna efficiency is beyond 35 %, both being large enough for practical applications. In particular, the proposed MIMO antenna system has a profile height of only 1.4 mm, which is possibly the smallest one achieved so far in the literature, making it suitable for laptops with a large display-to-body ratio.

This paper proposes a two-element multi-input multi-output (MIMO) open-slot antenna implemented on the display ground plane of a laptop computer for eight-band LTE/WWAN operations. The metal surroundings of the antennas have been well integrated as part of the radiation structure. In the single-element open-slot antenna, the nearby hinge slot (which is bounded by two ground planes and two hinges) is relatively large as compared with the open slot itself and acts as a good radiator. In the MIMO antenna consisting of two open-slot elements, a T slot is embedded in the display ground plane and is connected to the hinge slot. The T and hinge slots when connected behave as a radiator, whereas the T slot itself functions as an isolation element. With the isolation element, simulated isolation between the two elements of the MIMO antenna is raised from 8.3–11.2 to 15–17.1 dB in 698–960 MHz and from 12.1–21 to 15.9–26.7 dB in 1710–2690 MHz. Measured isolation with the isolation element in the desired low and high frequency ranges is 17.6–18.8 and 15.2–23.5 dB, respectively. Measured and simulated efficiencies for the two-element MIMO antenna with either element excited are both larger than 50% in the desired operating frequency bands.

A sub-6-GHz four-element multi-input multi-output (MIMO) slot antenna system was proposed in this study for fifth-generation (5G) tablet computers, where each antenna element was constructed using a slot structure. To effectively use the available space in a tablet and maximize the screen, we have deployed the MIMO antenna system on the left side-edge frame of the tablet. The MIMO antenna system measuring 37.2 × 7 mm2 consists of two identical 13.6 × 7 mm2 dual-slot-antenna units that are separated by 10 mm. The two closely spaced slot antennas in the same dual-slot-antenna unit are arranged asymmetrically mirrored of each other with respect to the system ground plane. Although the dual-slot-antenna unit is very compact, the isolation between the two slot antennas in the same unit can be enhanced by using an ungrounded full-wavelength strip resonator. With the two ungrounded resonators in the MIMO slot antenna system, the simulated intra-unit isolations at the mid-band frequency can be enhanced by about 3.5 dB to meet the design requirement. As a byproduct, the two ungrounded resonators in the MIMO antenna system can also enhance the simulated mid-band antenna efficiency by about 4.5% and lower the worst simulated ECC by 0.195, from 0.518 to 0.323. This MIMO antenna system can support the frequency band of 3400–3600 MHz for 5G. In the operating band, the measured isolation is larger than 11 dB, and the measured antenna efficiency is larger than 40%. The envelope correlation coefficients (ECCs) calculated from the measured complex E-field radiation patterns are all smaller than 0.23, making the proposed design suitable for 5G mobile communications that require fast transmission.