Designing miniaturized multiband antennas to cover both the 5G new radio frequencies (FR1 and FR2) simultaneously is a challenge for wireless communication researchers. This paper presents two antenna designs : a dual-band printed antenna of size 18 × 16 × 0.285 mm3 operating at FR1–5.8 GHz and FR2–28 GHz and a triple-band printed antenna with dimensions 30 × 25 × 0.543 mm3 operating at FR1–3.5 GHz and 5.8 GHz (sub-6 GHz microwave frequency bands) and FR2–28 GHz (mm-wave frequency band). The final projected triple-band antenna has a compact size with an impedance bandwidth of 12.71%, 11.32%, and 18.3% at 3.5 GHz, 5.8 GHz, and 28 GHz, respectively with the corresponding gain of 1.86 dB, 2.55 dB, and 4.41 dB. The measured radiation characteristics of the fabricated prototypes show that the proposed designs are suitable for trendy 5G-RFID and mobile Internet of things (IoT) applications.

This paper presents two compact slot array antennas for the 79 GHz automotive band integrated into a 28 µm thick benzocyclobutene (BCB) substrate attached to a 325 µm thick 5–20 Ω cm bulk resistivity silicon wafer. The two antennas are a transmit (TX) 1 × 8 slot array antenna with a size of 1 × 23 mm and a receive (RX) 8 × 8 slot array antenna with a size of 15 × 23 mm. Promising performance has been measured with the TX and RX subarray antennas (gain >4 dBi) with good matching to 50 Ω (RL > 10 dB) in the frequency range 70–90 GHz. By using a metal cavity, mounted on the back of the antenna, potential parallel plate or cavity modes could be reduced and the gain could also be increased by 2 dB. The measured and the simulated results are consistent.