The double L-shaped sleeve acts as a parasitic element to improve the bandwidth of the printed monopole antenna. The transmission line model method is used to determine the dimensions of the printed monopole to achieve the desired frequency. The distance between Port 1 and Port 2 is 11.3 mm.įront and back view of prototype MIMO antenna.Īs shown in Figure 1, the printed double-L sleeve monopole antenna consists of a printed monopole in the middle and two-symmetrical L-shaped sleeves at the sides. It is a microstrip monopole with offset fed antenna. The T-shaped microstrip feedline is fed at 11.4 mm from the left end of the feedline at Port 2. The length of the feedline, 34 mm, is 81.6% of quarter wavelength at 1800 MHz. The T-shaped microstrip feedline is used to excite the waveguide’s outer shell on the other side of the PCB. A T-shaped microstrip feedline is printed on the backside of the PCB. The two-symmetrical ground planes at the bottom of PCB are connected by the SMA connector. A SubMiniature version A (SMA) connector is soldered to the 50 ohm CPW. A CPW is used to feed the printed double-L sleeve monopole antenna at Port 1. The edges of the ground plane are extended to form an L-shaped ground plane. Two symmetrical ground planes are located at the bottom of the PCB surrounding the printed monopole. A printed double-L sleeve monopole antenna is printed on the front side of the printed circuit board (PCB). Figure 2 shows the front and back view of the prototyped antenna. The material chosen for the antenna is a FR4 substrate with dielectric permittivity of 4.6 and thickness of 1.6 mm. The proposed antenna design as shown in Figure 1 occupies the size of 80 × 50 mm 2.
The effects of the varying parameters of the proposed MIMO antenna on the antenna performance are also presented in this paper. The structure of the proposed antenna is described in detail in the following section. This proposed antenna can cover LTE 1800 frequency band for laptop or tablets application. In this paper, the proposed antenna is a combination of printed microstrip and a printed double-L sleeve monopole antenna. Isolated mode antenna technology is used to reduce the mutual coupling between the two ports. In, a dual feed single element antenna for 4G MIMO devices is proposed. In order to reduce mutual coupling between multiple antennas, a lot of research has been done in order to overcome this challenge. One of the main challenges in MIMO antenna design is to obtain good isolation characteristics between two antennas. Several challenges are faced in order to integrate multiple antennas into a laptop. Various types of sleeves have been proposed such as L-shaped sleeves and tilted sleeves. This additional resonant mode combines with the fundament resonant mode to generate wide bandwidth. The sleeves that are added to the ground plane of the monopole antenna act as a parasitic element to generate additional resonant mode. Printed sleeve monopole antennas are low profile with its planar structure. As the deployments of LTE 1800 continue to accelerate, the development and optimization of LTE 1800 antenna are beneficial to meet the modern demands of wireless terminals. A lot of researches have been done to develop LTE antennas, but there is lack of research for LTE 1800 MIMO antenna. The spectrum refarming from GSM 1800 to LTE 1800 is very cost effective. This is primarily due to the 1800 MHz band that is already being used for GSM 1800.
LTE 1800 has gained a lot of interests among wireless broadband operators. The LTE standard can solve this problem by supporting higher data rates, higher capacity, and lower latency. In recent years, advances in wireless technology have led to the insatiable demand for wireless broadband. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi. This antenna exhibits omnidirectional characteristics. The proposed antenna can operate in LTE 1800 (1710 MHz–1880 MHz). Isolation characteristics better than −15 dB can be obtained for the proposed MIMO antenna. A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide’s outer shell. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented.