Ming-yi Li

Ultra-wideband low-cost phased-array radars

Emerging radar applications require phased arrays that can operate over wide bandwidths to support multiband/multifunction operation. In response to that need, this paper presents a cost-effective implementation for extremely wide-band phased-array radars. Two designs are demonstrated, one operating from 3 to 12 GHz and the other operating from 8 to 20 GHz. These designs incorporate ultra-wideband antipodal tapered slot antennas, a novel cross-polarization suppressed array architecture, piezoelectric true-time-delay phase shifters, and broad-band high-power monolithic amplifiers. The resulting systems provide target detection and beam steering over the complete operating bandwidths. These results exceed the state-of-the-art for phased-array radars in terms of bandwidth and cost and should have direct applications in the development of ultra-wideband and multifunction radar systems.

Analysis and design of aperture-coupled microstrip patch antennas and arrays fed by dielectric image line

This paper presents the analysis and design of aperture-coupled microstrip patch antennas and arrays fed by an dielectric image line. A theory based on the cavity model of the microstrip patch antenna and the change in the modal voltage of the image line at the aperture was developed to analyze the single element aperture-coupled microstrip patch antenna. The theory developed was combined with the array theory to design linear traveling wave arrays at X-band and Ka-band frequencies. The required taper in the excitations of the individual patches of the array was achieved by varying the aperture dimensions. Experiments show very good results for the antennas and the arrays.

Novel low-cost beam-steering techniques

This paper summarizes and compares several techniques for beam steering without the use of conventional ferrite or solid-state phase shifters. Three methods are presented: a microstrip patch antenna array fed by a dielectric image line (DIL) controlled by a reflector plate, a multimicrostrip line fed Vivaldi antenna array controlled by piezoelectric transducers (PETs) and a movable grating film fed by dielectric image line. Both theoretical analyses and experimental measurements have been carried out. The measurement results agree very well with the predictions. These new techniques have many advantages, including low cost, broad bandwidth, low loss, wide scan angle, and simplicity. These low-cost beam-steering techniques should have many applications in microwave and millimeter-wave commercial systems.

A phased-array architecture for retrodirective microwave power transmission from the space solar power satellite

This paper presents a phased array architecture for retrodirective microwave wireless power transmission from the space solar power satellite (SPS). The proposed architecture uses a 2.9-GHz pilot beam and a 5.8-GHz transmit beam, with retrodirective phasing implemented directly at RF. Experimental and theoretical results are given to validate the approach.

A 10- to 21-GHz, low-cost, multifrequency, and full-duplex phased-array antenna system

This paper presents a novel phased-array antenna system with multifrequency, full-duplex operation, and wide-beam scanning. The system consists of a wideband power divider, a low-loss and low-cost multiline phase shifter controlled by dual piezoelectric transducers (PETS), a four-channel multiplexer, microwave monolithic integrated circuit (MMIC) amplifiers, and a stripline-fed Vivaldi antenna array. The multiline PET phase shifter has a low perturbation loss of less than 2 dB and a total loss of less than 4 dB up to 40 GHz, with a maximum phase shift of 650/spl deg/. Using dual-aligned PETS for bidirectional phase shifting results in wide scan angles of 38.6/spl deg/, 37.6/spl deg/, 43/spl deg/, and 40/spl deg/ for the four channels at 10, 12, 19, and 21 GHz, respectively. The four-channel diplexer demonstrates low insertion loss with high isolation between channels. The new multifrequency phased-array system provides wide-beam scanning and full-duplex capability using a simple, low-cost architecture. The system can be used for applications in mobile satellite communications.

A novel millimeter-wave beam-steering technique using a dielectric-image line-fed grating film

This paper introduces a novel, broadband, low-cost technique for beam steering at millimeter-wave frequencies using a moveable grating film fed by dielectric image line. An excellent radiation pattern is maintained over wide scan angles across the 30-40 GHz range, with up to 53/spl deg/ scanning reported at 35 GHz. Theoretical calculations closely predict the observed scan angle across the entire range of measurement.

Novel low-cost beam-steering techniques using microstrip patch antenna arrays fed by dielectric image lines

This paper presents novel low-cost beam-steering techniques using microstrip patch antenna arrays fed by dielectric image lines (DILs). Two approaches are designed and used. The first, DILs without reflector plate, are used for feeding microstrip patch antenna arrays. Antenna array radiation beams are scanned when the operating frequency sweeps. The second, a dielectric image line with a movable reflector plate (DILWRP), is developed. The beam direction of the antenna array is controlled and steered by changing the perturbation distance between DIL and movable reflector plate at a given operating frequency. Both types of patch antenna array structures are simple, low cost, easily fabricated, stable, and reliable. Eight-element patch antenna arrays fed by DIL and DILWRP have been designed, fabricated, and tested. Experiments show good performance and results. Measurement results of scanning angles agree well with theoretical predictions.

Circular-polarized reconfigurable grating antenna for low-cost Millimeter-wave beam-steering

This communication presents a circular-polarized (CP) reconfigurable grating antenna for low-cost millimeter-wave beam steering. A CP grating array is introduced. Using an inertialess mechanical movement, the grating design can be reconfigured along the surface of a dielectric image line, allowing a directive CP beam to steer across a wide range of angles. Over 43/spl deg/ of beam steering is achieved at 32.5 GHz with axial ratio less than 1 dB across the entire scan range. Measured performance agrees well with theory. These results are inherently scalable to higher millimeter-wave frequencies and should have numerous uses in emerging millimeter-wave satellite communications applications and other related systems for mobile communications and radar.

Broadband Microstrip-Coplanar Stripline-Fed Circularly Polarized Spiral Antenna

A wideband microstrip-coplanar stripline-fed circularly polarized spiral antenna is presented. An electromagnetic coupled wideband balun from microstrip line to coplanar stripline is developed to feed the spiral antenna. The antenna shows a measured return loss of better than 10 dB from 6.85 GHz to 11.9 GHz. The axial ratio is smaller than 3 dB from 7 to 11.5 GHz

Design and analysis of a reconfigurable dual-beam grating antenna for low-cost millimeter-wave beam-steering

This paper presents a reconfigurable dual-beam grating antenna for low-cost millimeter-wave beam steering. Experimental results indicate that this multibeam approach provides over /spl plusmn/50/spl deg/ beam steering at fixed frequencies across the entire 35 to 40 GHz band, with excellent radiation patterns maintained across the scans. An approximate analysis developed for the reconfigurable antenna closely predicts the observed scan angles and main beam radiation patterns across the complete range of scan states. These results should have numerous applications in millimeter-wave beam-steering technology.