On the Development of Multiband NB-IoT Antenna for Low-Power Wide Area Network Terminal

The design of a miniaturized noble multiband Inverted-F Antenna (IFA) suitable for integration in compact Internet of Things (IoT) terminals at centered frequencies of 704.35 MHz, 1122.9 MHz, and 1717.2 MHz, with narrow bandwidths of 26.327 MHz, 36.518 MHz, and 39.066 MHz, is discussed in this paper. Unlike other communication systems, NB-IoT devices have almost no bandwidth requirements, allowing for strong antenna miniaturization. The antenna can efficiently operate over the appropriate global NB-IoT frequency bands B4, B12, B13, B17, B28, B66, B70, B71, B85, and L bands. The proposed antenna is composed of a low-cost FR-4 (lossy) substrate with a dielectric constant of 4.4, a loss tangent of 0.025, and a standard thickness of 0.8mm, as well as a copper (annealed) patch and ground. A substrate measuring
$100\ \text{mm}\times 40\ \text{mm}$
and a patch measuring
$14.50\ \text{mm}\times 36.50\ \text{mm}$
are used. In a Far-field simulation, the proposed antenna structure's highest directivity is measured at 3.42 dBi, with reflection parameters of −22.41 dB, −29.398 dB, and −14.695 dB, respectively. The proposed antenna design is simulated using the finite element method in CST Microwave Studio, and it is suitable for operate in low bit rates covering long distances, battery powered and low-bandwidth devices.