A Novel Millimeter-Wave Dual-Fed Phased Array for Beam Steering

Abstract

A phased array antenna, used for shaping and steering the main antenna beam electronically to chosen directions within the predefined field of view, has been the key antenna system for satellite communications and military radars for decades. However, despite its high functional performance, it is still a very costly and complex solution for emerging wireless consumer applications such as high speed wireless communication and driving assistance systems due to the number of phase shifters and their complex control circuitry. Even more challenges are encountered with an increase in the number of channels if an antenna with high directivity is desired, such as routing RF and IF circuits, isolation of neighboring RF channels or calibration of a whole system.In order to eliminate the challenges stated above, a novel beam steering approach is presented in this dissertation based on the superposition of two squinted antenna beams. The two antenna beams are realized by exciting the opposite feeds of a dual-fed array antenna. A change in the phase difference and amplitude ratio between the input signals, using only one phase shifter and two variable gain amplifiers or only two I-Q vector modulators, steers the main beam in different directions. Due to its similar architecture, it exhibits all the advantages that a traveling wave antenna possesses as well, such as beam steering with the change of the operating frequency.Additionally, the sum and difference patterns can be obtained using this concept, allowing for an amplitude-comparison monopulse operation with a broad peak or a deep null at the broadside. Using this approach, beam nulls can also be steered towards interference directions, while keeping the shape and direction of the main beam unchanged. Another advantage is its high robustness against phase and amplitude errors due to analog hardware components in the RF path, which cannot be avoided in conventional phased arrays. A channel mismatch and crosstalk between neighbor RF channels or a temperature and time dependent array calibration can be minimized via this technique thanks to its unique topology, as well.In this work, an analytic antenna model has been derived and implemented in MATLAB using closed form expressions to analyze and optimize each relevant antenna parameter. Using this model, the development time becomes significantly shorter and the required computer memory is almost negligible.In order to prove the validity of the proposed novel beam steering approach, two different millimeter-wave (mm-wave) dual-feed antenna setups have been designed and implemented. In the first setup, commercial passive WR-10 components are used to perform the phase and i -iiamplitude changes manually. To demonstrate the full capability of electronic scanning, a second setup is built by employing an I-Q vector modulator instead of the waveguide phase shifter and the attenuator, which is controllable via input current signals. A mm-wave baredie transceiver MMIC which houses an integrated I-Q vector modulator in its ...

A Wideband Reconfigurable Antenna With 360° Beam Steering for 802.11ac WLAN Applications

“…7(b), the beam can be steered to 60° direction when turning on shorting vias groups DC biasing wires Battery 33.8 mm radius of the outer edge of the parasitic sector patch r 2 18.8 mm radius of radiating patch r 3 16 mm radius of the location of the shorting vias G1-G6 r 4 36.7 mm radius of the location of the shorting vias G7-G12 r 5 23.8 mm distance from inner edge of the joint stub to feed port r 6 30.8 mm radius of the location of the inner mounting screws r 7 19.5 mm distance of the DC wire hole to feed port r 8 9.1 mm radius of the inner hole on layer 3 r 9 45.2 mm radius of the outer edge of layer 3 r 10 43 mm radius of the location of the outer mounting screws r 11 21.2 mm distance from DGS outer edge to feed port r 12 9 4 0.85 mm radius of the holes for DC wires d 5 14.5 mm height of reflectors d 6 1.57 mm thickness of layer 1 d 7 0.8 mm radius of the shorting vias in G1-G6 d 8 0.5 mm radius of the shorting vias in G7-G12 d 9 0.5 mm thickness of inner ring in layer 2 d 10 1 mm slot width on layer 2 (spacing for PIN diode) d 11 0.6 mm slot depth on layer 2 (spacing for PIN diode) w 1 1.8 mm length of DC supply microstrip line (part 1) w 2 0.6 mm width of DC supply microstrip line w 3 2 mm pad width for shorting vias G7-G12 w 4 7 mm distance between two adjacent parasitic patches w 5 5 mm width of the stub connecting adjacent parasitic patches l 1 1.5 mm length of the dented slot (spacing for PIN diode) l 2 1 mm width of the dented slot (spacing for PIN diode) l 3 1.8 mm length of the dented slot (spacing for RF choke) l 4 0.6 mm width of the dented slot (spacing for RF choke) l 5 3 mm width of the dented slot (spacing for cap. and vias) l 6 3.1 mm width of the shape between two DGS slots (layer 2) l 7 3.9 mm pad length for shorting vias G7-G12 l 8 2 mm width of DC pad for G7-G12 l …”

Ten switched‐beams with 2 × 2 series‐fed 2.4 GHz array antenna and a simple beam‐switching network

“…A switched‐beam antenna system has the ability to choose one of many predefined beams in order to improve the strength of received signal from intended direction. Such type of smart antennas with the capability of beam‐switching in the intended direction can significantly improve the reliability and performance of communication link through improved signal to noise ratio (SNR) at receiver without increasing the transmit power . For example, the base station can determine the signal of interest (SOI) direction from any active user to switch its antenna beam in that direction to communicate with a intended mobile station with improved link performance (best reception) as depicted in Figure .…”

“…which results in additional complexity and cost to realize such antenna systems for large‐scale commercial applications. Several phased array antennas have been implemented with reduced number of beam controllers for required beam steering or beam switching capabilities . Such antenna systems either utilize CMOS technology based chips or a single phase shifter with separate gain controller for each array element to reduce the complexity and cost of phased array system.…”

Frequency-dependent behavioral-model-based nonlinear analysis and design of a low-profile transmit active phased array antenna

“…1,2 For these purposes, phased array antennas (PAA) can be a good candidate due to their many superiorities, such as high directivity, single and multiple beamforming, fast beam scanning, and spatial filtering. [1][2][3][4][5] Recently in, 3 an interesting dual-fed PAA concept was developed to obtain a beam steering up to 168 with a reduced complexity. The proposed series-fed array uses 2 phase shifters and 2 variable gain attenuators (VGA) in 2 opposite sides and adjusts the phase and amplitude ratios between them.…”