This paper presents a novel compact dual-band printed antenna with an omnidirectional radiation pattern for 5G WLAN. The antenna element comprises a star-shaped patch with six disc-shaped elements at the top and a defected ground structure at the bottom, having a radius of 3.77 mm for both. The proper feeding point and alignment with its element parameters help to achieve good impedance matching. The proposed antenna has a single center feed, a low profile, and a straightforward compact structure without any feeding complexity. A high reception fidelity antenna with comparable bandwidth and moderate gain is presented. The prototype radiator was printed on a 4 mm radius and a 1.6 mm thick dielectric substrate (Rogers RT/Duroid 5880), with a dielectric constant of 2.2. The designed antenna is fabricated and measured to validate the simulation result. The measured impedance bandwidth of 1.3 GHz (27.5–28.8 GHz) and 2.2 GHz (32.45–34.65 GHz) with a respective measured gain of 1.1 and 3.2 dBi are achieved at 28 and 34 GHz. The simulated radiation efficiency of above 95% is achieved for both bands. A good agreement between simulated and measured results of the proposed work shows that the proposed antenna is suitable for 5G short-range WLAN communications.

In this article, a sleeve antenna with a wide impedance bandwidth that consists of a coplanar waveguide line connected to a metallic cylinder is presented. The effect of design parameters on the impedance bandwidth is considered by some simulations. In addition to the wide impedance bandwidth, the omnidirectional pattern, high efficiency, low cost and easy fabrication process, and compact dimensions cause this antenna to be a good choice for some applications at low VHF/UHF frequency bands. Due to the flexible structure of this antenna, it is possible to cover the various frequency bands by changing the parameters of the antenna. In this work a typical model of the proposed antenna for the frequency range of 127 to 586 MHz is fabricated and compared with other previous works. An equivalent circuit model has been proposed to better understand how the antenna works. The proposed antenna has a bandwidth of about 128.7% for a voltage standing wave ratio (VSWR) of less than 3, compact size of 0.274λ × 0.047λ and higher than 90% efficiency.