Abstract
The millimeter-wave (mm-wave) band is expected to be the optimal solution for future wireless communication systems as it provides a wide bandwidth, which enhancing data transmission rate. Therefore, high-directive antennas, principal elements for mm-wave wireless communications, are used at the mm-wave band as they can overcome the negative effect of high path losses. A transmit-array antenna (TA) operates at the mm-wave band (around 28 GHz) with high aperture efficiency, high gain, wide bandwidth, and low-profile TA surface has been designed. Basically, the aperture efficiency of the TA depends on the unit cell (UC) characteristics, and feed antenna radiation pattern. Therefore, the UC elements designed based on capacitive differential feeding and true time delay techniques, as a result the designed UC has a wide bandwidth with a stable broadside radiation pattern, high cross-polarization discrimination and a full phase range (0-360°) and a maximum element loss of 0.5 dB. Moreover, the designed UC rotates the polarization of linearly polarized electromagnetic (EM) wave to its orthogonal direction with high efficiency, a polarization conversion ratio higher than 0.9 is achieved within the operating frequency band. The used techniques to design the proposed UC have a significant effect on TA antenna performance, in terms of gain and bandwidth. The TA antenna surface and the feeding antenna have been designed and fabricated. The maximum gain is 31.15 dBi. The 1 dB gain bandwidth is 12.7% while the 3 dB gain bandwidth is 21% around 28 GHz. The aperture efficiency is better than 50% and the cross-polarization level is less than -37 dB, on the frequency range from 25 to 31.5 GHz.
Highlights
M ILLIMETRE wave spectrum has received high attention by service providers because it can be the optimal solution to accommodated the high channel capacity demand
The horn is placed at the focal point of the transmit-array antenna (TA) aperture
Assuming the TA required gain is 30 dBi and the aperture efficiency is about 50%
Summary
M ILLIMETRE wave (mm-wave) spectrum has received high attention by service providers because it can be the optimal solution to accommodated the high channel capacity demand. The results were 7% of 1-dB gain bandwidth, 21.6 dBi of directivity, and 17% of aperture efficiency Later, they proposed circularly polarized discrete lens antennas in 60 GHz [13], which consist of two patch antennas separated by a common ground and connected by a via drilled through the substrate. In [15] another TA surface consist of five layers of Jerusalem crossd2i1poles is designed This design is considered better than the first design because it provides better measured results such as 34.64% aperture efficiency, SLL less than -15dB, 1-dB and 2-dB gain bandwidths of 10.2% and 14.83%, respectively. The main challenge facing transmit-array antenna designers is to design a UC with high performance, which includes full phase range, wide bandwidth, high transmission coefficients, and good UC radiation pattern characteristics. Usage of a substitute element causes destructive interference at the new wavefront and results in a gain reduction
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
