This letter presents a new approach for finite-element time-domain electromagnetic analysis. The new method combines the property of high-order approximation in the time domain with the crucial property of unconditional stability. The proposed method has been used in circuit simulation and relies on employing a specific formulation of the numerical inversion of the Laplace transform. The method is validated using one- and two-dimensional scattering from a dielectric object.
With the advent of number of applications in the mm-wave bands, antenna sizes are becoming small enough to fit them on mm-scale Integrated Circuits (ICs), commonly known as microchips. Integration of antenna on a chip along with the driving circuits in the standard CMOS process can enable a true RF System-on-Chip (SoC) solution, however, Silicon used in CMOS is very lossy and has a high dielectric constant. This results in low gain and efficiency antennas which also suffer from surface waves issues at mm-wave frequencies. In this paper, we will present Artificial Magnetic Conductor (AMC) surface to increase the gain/efficiency of the on-chip antenna realized in standard CMOS platforms. The gain and radiation efficiency of 1.7dBi and 42.52% are achieved respectively.
This paper presents early results from the investigation of a cryogenically cooled CMOS (Cryo-CMOS) low-noise amplifier (LNA). The LNA was designed in a bulk 65-nm CMOS process. Measurements were performed at 300 K and a noise temperature (figure) of 12 K (0.18 dB) was achieved at 1420 MHz (the neutral hydrogen line). The amplifier also exhibits $\mathrm {a}32 \pm 1.65$ dB gain, an input return loss better than 8.3 dB, an output return loss better than 15.6 dB and consumes a total of 105 mW, 51 mA from a 0.7-V supply and 69 mA from a 1-V supply. From simulations, the LNA is expected to achieve a noise temperature (figure) of 4.5 K (0.07 dB) at an ambient temperature of 77 K while consuming 35 mW, 22mA from a 1-V supply and 19 mA from a 0.7-V supply.
In this paper, a unit-cell for transmitarray antenna working at X-hand is presented. The unit-cell is designed to provide 1-bit phase quantization at 12 GHz according to ON/OFF state of switches. The unit-cell is based on a multi-layer structure with a combination of a C-patch and a ring slot loaded by a rectangular gap. The simulation results show that the unit-cell can provide two values of transmission phase with a step of 180 degrees at 12 GHz. A transmitarray antenna is also simulated to verify the performance of the unit cells. Simulated results show a good radiation pattern and validate the beam-switching capability.
In this paper, a new microwave sensor is presented for contactless monitoring of humidity in dry air stream. The platform is based on a pair of passive ring resonators, which are magnetically coupled. The chip-less sensing tag is implemented on a flexible RF substrate and is coupled to the reader resonator, as a result, contactless and highly sensitive sensing has been enabled. The tag integrated within commercial silica gel adsorbent holders to monitor the humidity. The microwave sensor operates at 3.47 GHz including the coupled tag. The noncontact nature of the proposed structure enables humidity monitoring in harsh industrial environment.
A shared-aperture design concept is presented for a dual-band array where the ratio of the frequencies is flexible. At the lower frequency, the array is dual-polarized and the elements are cavity-backed crossed slots. The height of the cavity is reduced by adopting an "inverted T" configuration. For the higher frequency, single-polarized slot subarrays are fitted between the crossed slots, and use ridged waveguide for high aperture efficiency. The all-metal design is inherently robust and its sandwich-like structure suits different fabrication techniques. The applications for this kind of antenna include both terrestrial and space-borne missions, particularly synthetic aperture arrays.
We present aspects in the design and test of a dualfrequency, dual-polarization microstrip antenna array, which operates in both L-band and X-band. The antenna is proposed for synthetic aperture radar (SAR) applications that require low weight, low profile, and compact designs. The prototype antenna unit cell consists of a single dual-polarized perforated L-band patch, with 36 dual-polarized X-band patches integrated into the same planar geometry. We present design concepts, simulation results, and measurement results for the fabricated prototype.
This paper presents in detail the design of a wideband unit-cell for X-band passive transmitarray. The unit-cell is based on multi-layer structure and consists of four conducting layers printed on two identical substrates. A set of eight unit-cells are optimized to cover full 360° phase range and to obtain eight transmission phase states with a step of 45° for a common -3 dB bandwidth of 2.0 GHz. To evaluate the performance of the proposed unit-cell, a transmitarray antenna is designed and simulated at X-band. The simulated results show that the transmitarray provides maximum gain of 23.6 dBi, corresponding to a high aperture efficiency of 38.0%.
The loss contributions of a Substrate Integrated Waveguide (SIW) with staggered vias is investigated and quantified using precision simulations. Besides choosing an appropriate substrate material and cladding smoothness, the main design factor to reduce SIW loss is to increase the substrate thickness. As the substrate thickness increases, the requirements for manufacturability force the use of larger diameter vias, which forces the staggering of the SIW via-wall to reduce the side-wall leakage. The gaps in the staggered vias degrades the purity of the TE 01 mode causing additional loss at discrete frequencies. Being cognisant of these effects fosters improved SIW design, including configuration and materials usage.
In this paper we present the design and fabrication of modified Luneburg lens antennas. The lens was designed using a quasi-conformal transformation optics approach and fabricated using additive manufacturing. We experimentally validated our methods by designing and fabricating a modified Luneburg lens operating at 24-40 GHz with a beamforming capability of -50° to 50°.
As of today, the application of space-time modulated media has been limited to parametric amplification, nonreciprocity, and frequency mixing. This article exhibits the functionality of the space-time modulated medium as a surface-wave antenna and demonstrates that a space-time modulated medium makes a perfect antenna. We first present the analytical solution for electromagnetic fields inside a space-time modulated medium. The analytical solution reveals the existence of surface-waves in such a medium as well as their temporal and spatial frequencies. We next introduce the concept of space-time surface-wave antenna system, where the transition of space-wave to surface-wave is utilized for a pure signal receive. The analytical solution is supported by FDTD numerical simulation of the medium, which gives a more in-depth insight into the analysis of the structure. The study is expected to pave the way for further study on the application of space-time media in antenna systems.
A comparison between the Rao-Glisson-Wilton (RGW) testing and point matching on the performance of the Random Auxiliary Sources (RAS) method is introduced. The comparison includes the method accuracy, numerical stability as well as suitability for general purpose solutions including special treatments. The comparison includes a smooth spherical structure in addition to a structure with edges. The results show an advantage for point matching for a fat and smooth-surface structure and RGW testing for structures with edges, which is an indication of the general-purpose suitability of the proposed approach.
In this paper, we are presenting a low-cost and high-gain beam steering silicon-based antenna array for sub-mmWave and THz applications, specifically for the next generation of 5G and radar systems. The antenna element is a parasitic tapered antenna for enhancing the gain while the size of the array is kept small. The beam steering happens by movement of a small metal sheet above each arm of the antenna array. The achieved gain of the system is 15.4 dBi at 86 GHz. The total scanning angle of 20 degrees is observed.
A modulated reactance is useful for realizing leaky-wave antennas. A grounded dielectric slab with thickness modulation is used to obtain a modulated reactance. The problem of a thickness-modulated slab is simplified by studying a constant-thickness grounded slab with an air gap between the physical structure and field points (where the impedance is evaluated). The surface reactance of a line source excited grounded slab is analyzed. Numerical evaluation of a Sommerfeld integral in the w plane is used to evaluate the fields near the source region. It is shown that near the source the reactance is not constant. Away from the source, an asymptotic approximation is used to evaluate the reactance. This allows a simplified synthesis procedure whereby the air gaps above the thickness-modulated slab can be ignored. The sinusoidal and square-wave impedance profiles are validated against a thickness-modulated slab using a commercial full-wave solver (CST).
Ridge Gap Waveguide (RGW) technology is a promising technology, especially for the millimeter wave bands. Hence, the need for antennas utilizing the same technology is growing fast to provide complete solutions to the applications in the millimeter wave band. Both linear polarization and circular polarization are deployed in the communication systems depending on the required system needs. Antennas with circular polarization have a remarkable advantage over the linear antennas since they overcome the polarization mismatching and misalignment problems. Here, a circularly polarized antenna that deploys a compact ferrite based differential phase shifter is introduced. The proposed antenna has an impedance matching bandwidth of 16.67% at 30 GHz with a 3 dB axial ratio. Simulations are obtained by two numerical packages, where both results have an excellent agreement with each other.
Recently, an antenna referred to as fringing field antenna, which is a narrow band in the 60 GHz band. Here, the gain of this antenna is enhanced by broadening the bandwidth and enhancing its gain. A dielectric superstrate is used making a gain enhancement by 4 (i.e., from 11.5 dBi to 15.5 dBi). In addition, 10-dB matching bandwidth is increased from 3.67 % (2.2 GHz) to 7.5 % (4.5 GHz).
This paper presents the design of Antipodal Vivaldi antenna (AVA) excited by a low-loss waveguiding structure commonly known as printed ridge gap waveguide (PRGW). The simulated result shows the designed antenna has wide impedance matching and an average gain of 13.5 (±1) dBi after dielectric loading over Ka-band.
Millimeter wave systems are in a growing need for compact size phased antenna arrays, hence, compact phase shifters, as well. In addition, there are other numerous applications like isolators, filters, and couplers that deploy the phase shifter as an essential component. To implement the proposed phase shifter the Ridge Gap Waveguide (RGW) structure is selected. RGW technology has the advantage of wideband operation over other technologies. Moreover, RGW structures have lower losses and better performance in the millimeter wave band. This work introduces a new RGW structure that deploys ferrite slabs to make a differential phase shifter with very compact size and ultra-flat phase. The proposed non-reciprocal 90° differential phase shifter has less than 10° of phase variations over the operating band.
In a large scale antenna system for 5G beamforming, the antenna modules can be designed as end-launch components. This concept is demonstrated by adopting half-height-pin gap waveguide technology to design a 4-element linear array. A quasi-TEM horn antenna is realized by flaring the double ridge that is surrounded by the half-height-pin electromagnetic band gap (EBG) structure. The single antenna element shows an impedance bandwidth (-10 dB) of 35% at 30 GHz with the realized gain of 7 dBi. The same impedance bandwidth is maintained with a 4-element linear array having a gain of 13.6 dBi at 30 GHz. The quasi-TEM double ridge gap waveguide (RGW) antenna is excited through a planar microstrip transition. The microstrip-to-ridge transition is designed and optimized to achieve better impedance match. The overall antenna array performance in the operating frequency range, 27.5~38 GHz, is stable with radiation efficiency around 78 %.
This paper presents a novel technique for improving radar accuracy. In particular, by studying the product of multiple radar beam pattern spectrums from different radar sub-module views, a refined and improved total radar response can be obtained. We examine this radar signal processing approach using a 24GHz frequency-modulated continuous wave (FMCW) radar system equipped with broadband 1.5GHz substrate integrated waveguide (SIW) antenna arrays to ensure high range resolution. The transmitter is defined by 4 sawtooth signals generated by separated radar sub-modules, each having a multiple input multiple output (MIMO) configuration with 4 receivers at each radar submodule. The measured spectral multiplication of the individual radar sub-modules results in a signal quality improvement of more than 10dB when compared to a MIMO radar configuration with the same architecture.
