GaN LNAs for Robust Receiving Systems in Radar and Space Applications

In this contribution a series of integrated circuits and methodologies, purposely developed for application in microwave receiving subsystems, will be presented. The integrated circuits, realized in GaN integrated technologies by different suppliers, find their applications in telecom systems as well as in RADAR ones, mainly for space-based apparatuses. The respective performance, as well as the key design methods will be presented in the contribution for bandwidths ranging from S-Band up to K-Band

Ka-band High-linearity and Low-noise Gallium Nitride MMIC Amplifiers for Spaceborne Telecommunications

Gallium Nitride is becoming an interesting solution for low-noise applications in the lower part of the millimetre-wave spectrum and is gaining increasing attention in the space community for microwave receiver functionalities. Lately, its maturity level has increased and its performance in terms of noise figure and operating frequency is reaching other advanced III-V technologies such as Gallium Arsenide and Indium Phoshpide. Moreover, Gallium Nitride features higher power handling capability in comparison to the previously mentioned III-V technologies. In this context, we have designed and characterized two demonstrator circuits of critical microwave receiver functionalities: a Low-Noise Amplifier and a Low-Distortion Amplifier operating at Ka-band. It is shown that GaN circuits compare well in terms of noise figure, gain, and operating frequency with respect to other advanced III-V technologies, and most of all exhibit superior linearity in terms of intermodulation distortion. The designed Low-Noise Amplifier exhibits state-of-the-art 1.2 dB Noise Figure in the 27-31 GHz bandwidth thanks to a profitable combination of 60- and 100-nm gate length transistors on the same MMIC. On the other hand, the Low-Distortion Amplifier features state-of-the-art +30 dBm Output Third Order Intercept point in the same operating bandwidth while requiring only 216 mW dc power. The presented electrical performances are validated by comparing these designs to others available in open literature through figures of merit that normalize trade-offs by transistor length (therefore a fair comparison) aiming to highlight the merits of the proposed design methodologies

Compact rectifier circuit design for harvesting gsm/900 ambient energy

In this paper, a compact rectifier, capable of harvesting ambient radio frequency (RF) power is proposed. The total size of the rectifier is 45.4 mm x 7.8 mm x 1.6 mm, designed on FR-4 substrate using a single-stage voltage multiplier at 900 MHz. GSM/900 is among the favorable RF Energy Harvesting (RFEH) energy sources that span over a wide range with minimal path loss and high input power. The proposed RFEH rectifier achieves measured and simulated RF-to-dc (RF to direct current) power conversion efficiency (PCE) of 43.6% and 44.3% for 0 dBm input power, respectively. Additionally, the rectifier attained 3.1 V DC output voltage across 2 k omega load terminal for 14 dBm and is capable of sensing low input power at -20 dBm. The work presents a compact rectifier to harvest RF energy at 900 MHz, making it a good candidate for low powered wireless communication systems as compares to the other state of the art rectifier

Realizing uwb antenna array with dual and wide rejection bands using metamaterial and electromagnetic bandgaps techniques

This research article describes a technique for realizing wideband dual notched functionality in an ultra-wideband (UWB) antenna array based on metamaterial and electromagnetic bandgap (EBG) techniques. For comparison purposes, a reference antenna array was initially designed comprising hexagonal patches that are interconnected to each other. The array was fabricated on standard FR-4 substrate with thickness of 0.8 mm. The reference antenna exhibited an average gain of 1.5 dBi across 5.25-10.1 GHz. To improve the array's impedance bandwidth for application in UWB systems metamaterial (MTM) characteristics were applied it. This involved embedding hexagonal slots in patch and shorting the patch to the ground-plane with metallic via. This essentially transformed the antenna to a composite right/left-handed structure that behaved like series left-handed capacitance and shunt left-handed inductance. The proposed MTM antenna array now operated over a much wider frequency range (2-12 GHz) with average gain of 5 dBi. Notched band functionality was incorporated in the proposed array to eliminate unwanted interference signals from other wireless communications systems that coexist inside the UWB spectrum. This was achieved by introducing electromagnetic bandgap in the array by etching circular slots on the ground-plane that are aligned underneath each patch and interconnecting microstrip-line in the array. The proposed techniques had no effect on the dimensions of the antenna array (20 mm x 20 mm x 0.87 mm). The results presented confirm dual-band rejection at the wireless local area network (WLAN) band (5.15-5.825 GHz) and X-band satellite downlink communication band (7.10-7.76 GHz). Compared to other dual notched band designs previously published the footprint of the proposed technique is smaller and its rejection notches completely cover the bandwidth of interfering signals

Overcoming Inherent Narrow Bandwidth and Low Radiation Properties of Electrically Small Antennas by Using an Active Interior-Matching Circuit

A technique is described to extend the working frequency-band and increase the radiation gain and efficiency of an electrically small antenna (ESA). The geometry of the proposed ESA is in the shape of an "H" structure. A small gap is included at the symmetry of the H-shape structure to embed an inductive load that is used to connect the two halves of the H-shaped antenna. With the lumped element inductor, the bandwidth of the H-shaped antenna is restricted by Chu-lower bound. However, it is demonstrated by analytical analysis and through 3D full-wave electromagnetic simulations that when the inductive load is replaced with negative reactance from a negative impedance converter (NIC) the antenna's bandwidth, radiation gain and efficiency performance can be significantly improved by similar to 40%, 3.6 dBi and 55%, respectively. This is because NIC acts as an effective interior matching circuit. The resonant frequency of the antenna structure with the inductive element was used to determine the required inductance variation in the NIC to realize the required bandwidth and radiation characteristics from the H-shaped antenna

Modified u-shaped resonator as decoupling structure in mimo antenna

This paper presents an isolation enhancement of two closely packed multiple-input multiple-output (MIMO) antenna system using a modified U-shaped resonator. The modified U-shaped resonator is placed between two closely packed radiating elements resonating at 5.4 GHz with an edge to edge separation distance of 5.82 mm (lambda(degrees)/10). Through careful adjustment of parametric modelling, the isolation level of -23 dB among the densely packed elements is achieved. The coupling behaviour of the MIMO elements is analysed by accurately designing the equivalent circuit model in each step. The antenna performance is realized in the presence and absence of decoupling structure, and the results shows negligible effects on the antenna performance apart from mutual coupling. The simple assembly of the proposed modified U-shaped isolating structure makes it useful for several linked applications. The proposed decoupling structure is compact in nature, suppress the undesirable coupling generated by surface wave and nearby fields, and is easy to fabricate

Efficient Wireless Power Transfer via Magnetic Resonance Coupling Using Automated Impedance Matching Circuit

In this paper, an automated impedance matching circuit is proposed to match the impedance of the transmit and receive resonators for optimum wireless power transfer (WPT). This is achieved using a 2D open-circuited spiral antenna with magnetic resonance coupling in the low-frequency ISM band at 13.56 MHz. The proposed WPT can be adopted for a wide range of commercial applications, from electric vehicles to consumer electronics, such as tablets and smartphones. The results confirm a power transfer efficiency between the transmit and receive resonant circuits of 92%, with this efficiency being sensitive to the degree of coupling between the coupled pair of resonators

Compact and low-profile on-chip antenna using underside electromagnetic coupling mechanism for terahertz front-end transceivers

The results presented in this paper show that by employing a combination of metasurface and substrate integrated waveguide (SIW) technologies, we can realize a compact and low-profile antenna that overcomes the drawbacks of narrow-bandwidth and low-radiation properties encountered by terahertz antennas on-chip (AoC). In addition, an effective RF cross-shaped feed structure is used to excite the antenna from its underside by coupling, electromagnetically, RF energy through the multi-layered antenna structure. The feed mechanism facilitates integration with the integrated circuits. The proposed antenna is constructed from five stacked layers, comprising metal-silicon-metal-silicon-metal. The dimensions of the AoC are 1 x 1 x 0.265 mm(3). The AoC is shown to have an impedance match, radiation gain and efficiency of <= -15 dB, 8.5 dBi and 67.5%, respectively, over a frequency range of 0.20-0.22 THz. The results show that the proposed AoC design is viable for terahertz front-end applications

Efficient wireless power transfer via magnetic resonance coupling using automated impedance matching circuit

In this paper, an automated impedance matching circuit is proposed to match the impedance of the transmit and receive resonators for optimum wireless power transfer (WPT). This is achieved using a 2D open-circuited spiral antenna with magnetic resonance coupling in the low-frequency ISM band at 13.56 MHz. The proposed WPT can be adopted for a wide range of commercial applications, from electric vehicles to consumer electronics, such as tablets and smartphones. The results confirm a power transfer efficiency between the transmit and receive resonant circuits of 92%, with this efficiency being sensitive to the degree of coupling between the coupled pair of resonators

Miniaturization Trends in Substrate Integrated Waveguide (SIW) Filters: A Review

This review provides an overview of the technological advancements and miniaturization trends in Substrate Integrated Waveguide (SIW) filters. SIW is an emerging planar waveguide structure for the transmission of electromagnetic (EM) waves. SIW structure consists of two parallel copper plates which are connected by a series of vias or continuous perfect electric conductor (PEC) channels. SIW is a suitable choice for designing and developing the microwave and millimetre-wave (mm-Wave) radio frequency (RF) components: because it has compact dimensions, low insertion loss, high-quality factor (QF), and can easily integrate with planar RF components. SIW technology enjoys the advantages of the classical bulky waveguides in a planar structure; thus is a promising choice for microwave and mm-Wave RF components