On the Design of Plus Slotted Fractal Antenna Array

A new technique which is a combination of fractal antenna and array antenna is presented to design Plus Slotted Fractal Antenna Array (PSFAA) in this paper. PSFAA with corporate feed operates at 2.5 GHz frequency. PSFAA is designed on FR4 substrate material with permittivity 4.4 and height 1.6 mm. PSFAA is designed up to 2nd iteration. High Frequency Structure Simulator (HFSS) software is used for simulation of PSFAA. The proposed antenna array operates at three bands with five frequencies 2.5 GHz, 4.1 GHz, 6.9 GHz, 7.4 GHz and 8.2 GHz. Simulated Return losses results of proposed PSFAA are -22.15 dB, -19.44 dB, -25.21 dB, -10 dB, -12.45 dB at above frequencies respectively. It has a gain of 9.22 dB at resonant frequency 2.5 GHz whereas conventional antenna array has a gain of 5.15 dB at resonant frequency 2.5 GHz. Return losses and gain of PSFAA also improved from conventional antenna array at various resonant frequencies.

Ultra-wideband low radar cross-section metasurface and its application on waveguide slot antenna array

A novel approach devoted to achieving ultra-wideband radar cross section reduction（RCSR） of a waveguide slot antenna array（WGSAA） while maintaining its radiation performance is proposed. Three kinds of artificial magnetic conductors（AMCs） tiles consisting of three types of basic units resonant at different frequencies are designed and arranged in a novel quadruple-triangle-type configuration to create a composite planar metasurface. The proposed metasurface is characterized by low radar feature over an ultra-wideband based on the principle of phase cancellation. Both simulated and measured results demonstrate that after the composite metasurface is used to cover part of the antenna array, an ultrawideband RCSR involving in-band and out-of-band is achieved for co-and cross-polarized incident waves based on energy cancellation, while the radiation performance is well retained. The proposed method is simple, low-cost, and easy-tofabricate, providing a new method for ultra-wideband RCSR of an antenna array. Moreover, the method proposed in this paper can easily be applied to other antenna architectures.

Substrate Integrated Waveguide Based Monopulse Slot Antenna Arrays for 60 GHz Applications

Monopulse slot antenna arrays based on substrate integrated waveguide （SIW） are proposed for the application of 60 GHz mono- pulse tracking systems in this paper. The sum-difference monopulse comparator can provide a high amplitude and phase balance over wide frequency band and no phase delay technique is required for the difference channel. Resonant slot antennas are adopted as the radiating elements since they can be integrated with the sum-difference monopulse comparator in a single layer with a compact size. Two monopulse arrays with 2× 4 and 4×4 slot elements are designed, fabricated, and measured. Measured results show that the proposed antenna arrays have wide bandwidth covering the unlicensed 60-GHz band. The peak sum beam gain is 13.85 dBi for the 2 ×4 element array and 16.24 dBi for the 4×4 element array. The peak difference beam gain is 11.20 dBi for the 2×4 element array and 12.11 dBi for the 4×4 element array and the maximum null depth can reach -40 dB.