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The authors propose a 4 × 4 circularly polarized (CP) antenna array with wide impedance bandwidth and axial‐ratio (AR) bandwidth and design the same for 60‐GHz applications. The overall structure of the proposed antenna array consists of a cavity‐back circular patch array and two layer feed‐networks. The upper feed‐network is with four TE340 high‐order mode substrate integrated cavities (SIC). Fed with SIC, circular patches with a pair of 42°‐inclined slits can achieve circular polarization. In order to improve the AR bandwidth and gain performance, the substrate integrated waveguide (SIW) sequential rotation feeding technique is utilized in the lower feed‐network. For proof of concept, the 4 × 4 array is fabricated and measured. Measured results show that −10‐dB impedance bandwidth of the proposed antenna array is 27.2% from 52 to 68.4 GHz and 3‐dB AR bandwidth is 18.9% from 55.7 to 67.3 GHz. Furthermore, the 3‐dB gain bandwidth is 26.2% from 53 to 69 GHz with a peak gain reaching 19.3 dBic at 62 GHz. [ABSTRACT FROM AUTHOR]

A novel ultra‐wideband (UWB) bandpass filter (BPF) with a very compact size and improved out‐of‐band performance is proposed in this letter. The main circuit structure is a composite right‐/left‐handed transmission line unit cell, which has UWB bandpass characteristic as well as compact size. Moreover, two anticoupled line structures added at both ends of the unit cell can produce a new resonant mode and three transmission zeros, so the passband response and upper stopband performance can be improved. The proposed filter is implemented and measured, which shows its 3 dB passband ranges from 3.3 to 10.9 GHz with a fractional bandwidth of 110.9%. Its insertion loss is about 0.6 dB at the centre frequency, while the return loss is better than 13 dB. In addition, the measured results also show the proposed filter has a wide stopband from 11.4 to 30 GHz, whose rejection level is greater than 18 dB. The size of the filter is only 7.4 × 6.4 mm, equal to 0.22 × 0.20 λg. Both the simulated and measured results are in good agreement. [ABSTRACT FROM AUTHOR]

This paper presents a cavity-backed dual-slot antenna in 0.13-μm SiGe BiCMOS technology. The dual-slot structure is excited by a cross-shaped strip line and a cavity which is formed by the topmost metal layer connected to the bottom metal layer through vias in between. By adopting dual-slot and cross-shaped feed line, the bandwidth is significantly enhanced by 196% compared with the single-slot antenna with straight feed line. The reason for bandwidth enhancement has been analyzed. The proposed antenna shows a measured impedance bandwidth of 15.2 GHz from 248.2 to 263.4 GHz for | S 11| < −10 dB. The simulated and measured peak gains of the cavity-backed dual-slot antenna are −1.3 and −2.1 dBi, respectively. The simulated radiation efficiency is 31.1%. The total size of the antenna is 0.46 mm × 0.48 mm. [ABSTRACT FROM AUTHOR]