A compact monopole super wideband antenna has been designed and fabricated in this study. The proposed antenna consists of an octagonal‐ring shaped patch with a stub positioned on the top right corner of it to enhance the impedance bandwidth. Further improvement is ensured by optimally shifting both the patch and feed line away from the center line, and introducing a notch on the ground plane. The fabricated antenna covers the frequency band from 2.59 to 31.14 GHz with a reflection coefficient of |S11| ≤  − 10 dB. It has a bandwidth of 28.55 GHz, fractal bandwidth percentage of 169% and bandwidth ratio of 12.02:1. Omnidirectional radiation characteristics are observed over the operating bandwidth in the far‐field measurements. Furthermore, the far‐field radar cross section measurement of the antenna is also simulated on PC and relatively low values are obtained through the operating bandwidth. Presented antenna has a relatively small size (40 × 40 × 1.01 mm3) and exhibits good gain and efficiency characteristics in comparison to studies with similar bandwidth.

A planar and compact substrate integrated waveguide (SIW) cavity backed antenna and a 2 × 2 multi‐input multi‐output (MIMO) antenna are presented in this study. The proposed antenna is fed by a grounded coplanar waveguide (GCPW) to SIW type transition and planned to be used for millimeter‐wave (mm‐wave) fifth generation (5G) wireless communications that operates at 28, 38, 45, and 60 GHz frequency bands. Moreover, the measured impedance bandwidth (|S11| ≤  − 10 dB) of the antenna covers 27.55 to 29.36, 37.41 to 38.5, 44.14 to 46.19, and 57.57 to 62.32 GHz bands and confirms the quad‐band characteristic. Omni‐directional radiation characteristics are observed in the far‐field radiation pattern measurements of the antenna over the entire operating frequency. The reported antenna is compact in size (9.7 × 13.3 × 0.6 mm3) and the gain values at each resonance frequency are measured as 3.26, 3.28, 3.34, and 4.51 dBi, respectively. Furthermore, the MIMO antenna performance is evaluated in terms of isolation, envelope correlation coefficient and diversity gain.

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This article proposes a substrate integrated waveguide (SIW) antenna fed by microstrip transmission to operate in V‐band and fifth generation (5G) (60/70 GHz band) applications. The proposed millimeter wave (mm‐wave) antenna has an impedance bandwidth of 25.68 GHz (fractional bandwidth of 41%) between 49.77 and 75.45 GHz frequency and has a maximum realized gain of 3.75 dBi. Compared with other studies, the reported antenna has a size reduction of up to 73% with its 8 × 9.7 mm2 (1.33λ×1.61λ) dimension. The designed SIW patch is also fed by grounded coplanar waveguide transmission and its results are compared with the one fed by microstrip transmission line. Another important feature of the proposed antenna is that it has a low production cost, since it is printed on a cheap FR4 substrate material. Therefore, the proposed antenna has the potential to meet all the necessary requirements to be used for V‐band portable devices and applications. A 2 × 2 multiple‐input multiple‐output antenna based on the proposed antenna structure is also analyzed with respect to isolation, diversity gain and envelope correlation coefficient and acceptable results are obtained.

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