Abstract
This paper presents an antenna that utilizes two beam steering techniques in concert in order to improve the antenna gain and steering resolution. Phased array steering is employed to achieve coarse resolution beam steering while parasitic steering is employed to achieve fine resolution beam steering within each coarse angle step provided by the phased array. A proof-of-concept antenna operating at 11.5 GHz was designed, fabricated and measured. The antenna incorporated 3-bit phase shifters and achieved a steering resolution of 1° over a steering range of ±40°. In order to achieve the same steering resolution, using a conventional array, it would be necessary to use 6-bit phase shifters. When compared to a conventional array the realised gain of the novel antenna was 4 dB higher. The antenna shows an improvement in scan loss when steering off boresight. The key advantage of the proposed Hybrid Parasitic Array Antenna is its low profile and high steering speed when compared with the alternative steering techniques.
Highlights
There is a growing need for beam steerable antennas, capable of fine angle steering, for applications such as: 5G millimetre wave access, backhaul, as well as anti-collision and vehicular radar
In [4], two lenses were used to achieve a steering resolution of 7.5° and a steering range of ±30°. This is a finer steering resolution compared to other Integrated Lens Antenna (ILA); it comes at the cost of increased design and fabrication complexity
The key advantage of the proposed hybrid parasitic array antenna (HPAA) is its low profile and high steering speed when compared with the alternative steering techniques
Summary
There is a growing need for beam steerable antennas, capable of fine angle steering, for applications such as: 5G millimetre wave access, backhaul, as well as anti-collision and vehicular radar. Several techniques for beam steering have been reported [1]; most of the techniques support only discrete steering in large angle steps (>10°) and are incapable of fine beam steering (i.e. in steps of 1° to 5°) without degrading the performance of the antenna. In order to achieve fine resolution beam steering, using this approach, it is necessary to use phase shifters having a moderate to large number of bits (5-6 bits). The insertion loss of a switched line phase shifter is proportional to the number of bits. This reduces the amplitude of the signal fed to the antenna. The ILA approach yields steering in large discrete steps and suffers redundancy as only one driven element is used at any given instance of time
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