Chih-Yu Tsai

Small-Size Stacked Inverted-F Antenna With Two Hybrid Shorting Strips for the LTE/WWAN Tablet Device

The stacked inverted-F antenna with two hybrid shorting strips placed close to the antennas feeding strip can provide two wide operating bands to cover long-term evolution/wireless wide-area network operation (698-960/1710-2690 MHz) in the tablet device. The antennas lower and higher bands are, respectively, contributed by the longer and shorter arms of the antenna. The two hybrid shorting strips include an inductive shorting strip (chip-inductor-loaded strip) and a capacitive shorting strip which capacitively couples to the antennas shorter arm. The longer arm is also coupled through a chip inductor to the feeding strip such that the longer arm has a decreased resonant length for the low-band operation and, on the other hand, has very small effects on the high-band operation, which is mainly contributed by the shorter arm. The feeding strip is also embedded with a chip capacitor such that an internal high-pass matching circuit formed by the inductive shorting strip and the capacitive feeding strip is obtained to greatly widen the antennas low-band bandwidth, with small effects on the high-band operation. On the other hand, the capacitive shorting strip is added to greatly enhance the bandwidth of the antennas higher band, with small effects on the low-band operation. Two wide operating bands are hence easily obtained and adjusted. The antenna can also be recessed in a small ground clearance of 10 × 35 mm 2 inside the tablet device such as a tablet computer in this study. Details of the proposed antenna are presented.

Low-Profile Dual-Wideband Inverted-T Open Slot Antenna for the LTE/WWAN Tablet Computer With a Metallic Frame

An inverted-T open slot (ITOS) antenna with a low profile suitable for the LTE/WWAN tablet computer with a metallic frame is presented. With a low profile of 7 mm above the top edge of the device ground plane of the tablet computer, the ITOS antenna can provide two wide operating bands of 698-960 and 1710-2690 MHz to cover the LTE/WWAN operation. The ITOS antenna shows a simple structure and can fit in the narrow region between the metallic frame and the display panel of the tablet computer. The lower and higher operating bands of the antenna can be, respectively, controlled by the low-band and high-band feeds thereof. The low-band feed excites the antennas longer slot arm to obtain a wide lower band covering the 698-960 MHz band. The high-band feed excites the antennas shorter slot arm to achieve a wide higher band covering the 1710-2690 MHz band. Working principle of the low-profile ITOS antenna for generating the dual-wideband operation is described. Simulated and experimental results of the antenna are presented and discussed.

IFA-Based Metal-Frame Antenna Without Ground Clearance for the LTE/WWAN Operation in the Metal-Casing Tablet Computer

A metal-frame antenna for the long-term evolution/wireless wide area network (LTE/WWAN) operation in the metal-casing tablet computer is presented. The antenna is formed by using two inverted-F antenna (IFA) structures to provide a low band and a high band to, respectively, cover the LTE/WWAN operation in the 824-960 and 1710-2690 MHz bands. The larger IFA has a longer radiating metal strip for the low band, and the smaller IFA has a shorter radiating metal strip for the high band. The two radiating metal strips are configured to be a portion of the metal frame disposed around the edges of the metal back cover of the tablet computer. The projection of the metal frame lies on the edges of the metal back cover, such that there is no ground clearance between the projection and the metal back cover. Furthermore, the feeding and shorting strips with matching networks therein for the two IFAs are disposed on a small dielectric substrate (feed circuit board), which is separated from the system circuit board and the metal back cover. In this case, there is generally no planar space of the metal back cover and system circuit board occupied, and the antenna can cover the 824-960/1710-2690 MHz bands. Results of the proposed antenna are presented. An extended study is also presented to show that the antennas low-band coverage can be widened from 824-960 to 698-960 MHz. The wider bandwidth coverage is obtained when a switchable inductor bank is applied in the larger IFA.

Half-Loop Frame Antenna for the LTE Metal-Casing Tablet Device

The use of metal casing is attractive to achieve robustness of modern slim tablet devices. The metal casing includes the metal back cover and the metal frame around the edges thereof. For such metal-casing tablet devices, the frame antenna that uses a part of the metal frame as an antennas radiator is promising to achieve wide bandwidths for mobile communications. In this paper, the frame antenna based on the simple half-loop antenna structure to cover the long-term evolution 746-960 and 1710-2690 MHz bands is presented. The half-loop structure for the frame antenna is easy for manufacturing and increases the robustness of the metal casing. The dual-wideband operation of the half-loop frame antenna is obtained by using an elevated feed network supported by a thin feed substrate. The measured antenna efficiencies are, respectively, 45%-69% and 60%-83% in the low and high bands. By selecting different feed circuits, the antennas low band can also be shifted from 746-960 MHz to lower frequencies such as 698-840 MHz, with the antennas high-band coverage very slightly varied. The working principle of the antenna with the elevated feed network is discussed. The antenna is also fabricated and tested, and experimental results are presented.

Compact eight MIMO antennas for 5G smartphones and their MIMO capacity verification

The handset or smartphone antenna has evolved from the external antenna before the year 2000 to the internal antenna and casing-integrated antenna for 2G/3G/4G communications till now. For the fifth-generation (5G) communications, it is expected that the Massive MIMO system is very promising for applications and a large number of MIMO antennas will be attractive to be deployed in the smartphone to effectively increase the channel capacity. In this paper, promising compact eight MIMO antennas in the smartphone are presented. The MIMO antennas are operated in the 3.5-GHz band (3400~3600 MHz), which has been recently identified in WRC-15 for global mobile broadband services in the future. The achievable MIMO channel capacities for the proposed compact eight MIMO antennas are calculated and verified by MIMO OTA (over-the-air) testing in the open space. Results are presented and discussed.

Combined-type dual-wideband and triple-wideband LTE antennas for the tablet device

Two combined-type tablet device antennas for LTE dual-wideband and LTE triple-wideband operations are presented. For the triple-wideband LTE antenna, it is formed by combining an inverted-F antenna (IFA) to cover the LTE low band (698~960 MHz) and a coupled-fed loop antenna to cover the LTE middle band (1710~2690 MHz) and high band (3400~3800 MHz). Such a triple-wideband LTE antenna occupies a small ground clearance of 10 × 30 mm2 and a thin thickness of 3 mm. For the dual-wideband LTE antenna, it is formed by combining an IFA and a monopole having a capacitive shorting strip, so as to provide two wide operating bands to cover the LTE operation in the 698~960 and 1710~2690 MHz bands. Results of the two combined-type LTE antennas are presented and discussed.