High performance on-chip array antenna for terahertz integrated circuits

In this letter a novel on-chip array antenna is investigated which is based on CMOS 20μm Silicon technology for operation over 0.6-0.65 THz. The proposed array structure is constructed on three layers composed of Silicon-Ground-Silicon layers. Two antennas are implemented on the top layer, where each antenna is constituted from three sub-antennas. The sub-antennas are constructed from interconnected dual-rings. Also, the sub-antennas are interconnected to each other. This approach enhances the aperture of the array. Surface waves and substrate losses in the structure are suppressed with metallic via-holes implemented between the radiation elements. To excite the structure, a novel feeding mechanism is used comprising open-circuited microstrip lines that couple electromagnetic energy from the bottom layers to the antennas on the top-layer through slot-lines in the middle ground-plane layer. Simulation results show the proposed on-chip antenna array has an average radiation gain, efficiency, and isolation of 7.82 dBi, 32.67%, and -33 dB, respectively

Silicon-Based 0.45-0.47 THz Series-Fed Double Dielectric Resonator On-Chip Antenna Array Based on Metamaterial Properties for Integrated-Circuits

The antenna array designed to operate over 0.45-0.47 Terahertz comprises two dielectric resonators (DRs) that are stacked vertically on top of each other and placed on the surface of the slot antenna fabricated on a silicon substrate using standard CMOS technology. The slot created in the silicon substrate is meandering and is surrounded by metallic via-wall to prevent energy dissipation. The antenna has a maximum gain of 4.5dBi and radiation efficiency of 45.7% at 0.4625 GHz. The combination of slot and vias transform the antenna to a metamaterial structure that provides a relatively small antenna footprint

Energy harvesting circuit with high RF-to-DC conversion efficiency

This paper presents an energy harvesting circuit for high efficiency performance. The proposed circuit consists of an RLC shunt resonance circuit integrated to an RF antenna. The resonance circuit is used to (i) selectively pick the desired signal whose output is fed to a Cockcroft–Walton voltage multiplier circuit; and (ii) match the impedance of the antenna with the Cockcroft–Walton voltage multiplier circuit for optimum power (DC) transfer. The proposed circuit exhibits an efficiency of 68% for an input power of 200 microwatts

Array antenna for synthetic aperture radar operating in X and Ku-Bands: a study to enhance isolation between radiation elements

Modern synthetic aperture radars (SAR) require a system bandwidth of greater than 1 GHz. Waveguide slot antennas are popular for use in SAR applications because of their inherent advantages, namely high efficiency and power handling capability, but such antennas have a limited bandwidth. Although the bandwidth of slot antennas can be broadened by using ridge waveguides however this approach introduces manufacturing complexity and is costly. A novel solution is presented in this paper to realize a large bandwidth by using 2×3 array antenna where the mutual coupling between the radiating elements is suppressed by inserting an isolation wall between the radiating elements. The isolation wall comprises three intercoupled U-shaped microstrip transmission-lines. With this technique the antenna’s bandwidth for VSWR<1.5 is greater than 2 GHz inside the X- and Ku-bands

A new waveguide slot array antenna with high isolation and high antenna bandwidth operation on Ku- and K- bands for radar and MIMO systems

In this paper a novel technique is proposed to reduce the mutual coupling between the radiating elements of a waveguide slot array antenna. This is achieved by inserting slots between the waveguide oval shaped slots. The reference waveguide array antenna used in the study was implemented with an arrangement of 3×5 oval shaped slots. By incorporating linear slots between the radiating oval shaped slots in both horizontal and vertical directions significant reduction in mutual coupling is achieved of 24 dB, 20 dB, and 32 dB in the frequency bands of 12.95-13.75 GHz (Ku-band), 15.45-16.85 GHz (Ku-band), and 18.85-23.0 GHz (K-band), respectively. Edge-to-edge distance between the slot radiators is 0.2λ, which is at least two-fold smaller than conventional array antennas. With the slot isolators the antenna’s minimum and maximum gains improve by 53.5% and 25.5%, respectively. In addition, the radiation patterns are unaffected. The proposed method is simple to implement, low cost solution mass production

Mutual-Coupling Reduction in Metamaterial Substrate Integrated Waveguide Slotted Antenna Arrays Using Metal Fence Isolators for SAR and MIMO Applications

A new type of mutual coupling reduction technique is applied to metamaterial substrate integrated waveguide (SIW) slotted antennas array. The circular shaped reference SIW antenna is constructed from Alumina substrate with dimensions of 40×5×1.5 mm3. Embedded in the reference antenna is an array of 38 slots with dimensions of 2×1×1.5 mm3. The reference SIW antenna covers six frequency bands from X- to Ku-bands with maximum and average isolation between the radiation slots of approximately -20 dB and -10 dB, respectively. Isolation was increased by inserting metal fences between the radiation slots, which also improves the antenna’s impedance matching properties. Maximum, minimum, and average suppression on mutual coupling between radiation slots after application of the metal fences are 20 dB, 8 dB, and 13 dB, respectively. The proposed metal fence isolators (MFI) improve the radiation patterns without degrading the antenna’s performance. With MFI the maximum gain achieved improves by ~10%. The technique is simple to implement and proposed for synthetic aperture radar (SAR) and multiple input multiple output (MIMO) applications

New approach to suppress mutual coupling between longitudinal-slotted arrays based on SIW antenna loaded with metal-fences working on VHF/UHF frequency-bands: study, investigation, and principle (conference paper : Asia-Pacific Microwave Conference)

In this work it is demonstrated that substrate integrated waveguide longitudinal slotted array antenna (SIWLSAA) which is loaded with metal fences exhibits high-isolation across VHF/UHF bands. A reference SIWLSAA used for comparison purpose comprises of 3×6 slotted arrays constructed on the top and bottom sides of the FR-4 lossy substrate has maximum isolation of -63 dB between its radiation slots. Improvement in isolation is demonstrated using a simple new technique based on inserting a metal fence between each row of slot arrays. The resulting isolation is shown to be is better than -83 dB across 200 MHz to 1.0 GHz with gain greater than 1.5 dBi, and side-lobe level less than -40 dB. The proposed SIWLSAA is compact and has dimensions of 40×10×5 mm3 (0.026λx0.006λx0.002λ) where λ is 200 MHz. The proposed structure should find application in multiple-input multiple-output (MIMO) and radar systems

Mutual coupling suppression between two closely placed microstrip patches using EM-bandgap metamaterial fractal loading

An approach is proposed to reduce mutual coupling between two closely spaced radiating elements. This is achieved by inserting a fractal isolator between the radiating elements. The fractal isolator is an electromagnetic bandgap structure based on metamaterial. With this technique, the gap between radiators is reduced to ∼0.65λ for the reduction in the mutual coupling of up to 37, 21, 20, and 31 dB in the X-, Ku-, K-, and Ka-bands, respectively. With the proposed technique, the two-element antenna is shown to operate over a wide frequency range, i.e., 8.7–11.7, 11.9–14.6, 15.6–17.1, 22–26, and 29–34.2 GHz. Maximum gain improvement is 71% with no deterioration in the radiation patterns. The antenna’s characteristics were validated through measurement. The proposed technique can be applied retrospectively and is applicable in closely placed patch antennas in arrays found in multiple-input multiple-output and radar systems

High-performance 50μm silicon-based on-chip antenna with high port-to-port isolation implemented by metamaterial and SIW concepts for THz integrated systems

A novel 50μm Silicon-based on-chip antenna is presented that combines metamaterial (MTM) and substrate integrated waveguide (SIW) technologies for integration in THz circuits operating from 0.28 to 0.30 THz. The antenna structure comprises a square patch antenna implemented on a Silicon substrate with a ground-plane. Embedded diagonally in the patch are two T-shaped slots and the edges of the patch is short-circuited to the ground-plane with metal vias, which convert the structure into a substrate integrated waveguide. This structure reduces loss resulting from surface waves and Silicon dielectric substrate. The modes in the structure can be excited through two coaxial ports connected to the patch from the underside of the Silicon substrate. The proposed antenna structure is essentially transformed to exhibit metamaterial properties by realizing two T-shaped slots, which enlarges the effective aperture area of the miniature antenna and significantly enhances its impedance bandwidth and radiation characteristics between 0.28 THz to 0.3 THz. It has an average gain and efficiency of 4.5dBi and 65%, respectively. In addition, it is a self-isolated structure with high isolation of better than 30dB between the two ports. The on-chip antenna has dimensions of 800x800x60μm3This work is partially supported by innovation programme under grant agreement H2020 -MSCA-ITN-2016 SECRET 722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/EO/22936/1

Silicon-based 0.450-0.475 THz series-fed double dielectric resonator on-chip antenna array based on metamaterial properties for integrated-circuits

The antenna array designed to operate over 0.450-0.475 Terahertz comprises two dielectric resonators (DRs) that are stacked vertically on top of each other and placed on the surface of the slot antenna fabricated on a silicon substrate using standard CMOS technology. The slot created in the silicon substrate is meandering and is surrounded by metallic via-wall to prevent energy dissipation. The antenna has a maximum gain of 4.5dBi and radiation efficiency of 45.7% at 0.4625 THz. The combination of slot and vias transform the antenna to a metamaterial structure that provides a relatively small antenna footprint. The proposed series-fed double DRs on-chip antenna array is useful for applications in THz integrated circuits.This work is partially supported by innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E0/22936/1