Open Access
High gain/bandwidth off-chip antenna loaded with metamaterial unit-cell impedance matching circuit for sub-terahertz near-field electronic systems
(Springer, 2022) Alibakhshikenari, Mohammad; Virdee, Bal S.; Mariyanayagam, Dion; Vadalà, Valeria; Naser Moghadasi, Mohammad; See, Chan H.; Dayoub, Iyad; Aïssa, Sonia; Livreri, Patrizia; Burokur, Shah Nawaz; Pietrenko-Dabrowska, Anna; Falcone Lanas, Francisco; Koziel, Slawomir; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
An innovative of-chip antenna (OCA) is presented that exhibits high gain and efciency performance at the terahertz (THz) band and has a wide operational bandwidth. The proposed OCA is implemented on stacked silicon layers and consists of an open circuit meandering line. It is shown that by loading the antenna with an array of subwavelength circular dielectric slots and terminating it with a metamaterial unit cell, its impedance bandwidth is enhanced by a factor of two and its gain on average by about 4 dB. Unlike conventional antennas, where the energy is dissipated in a resistive load, the technique proposed here signifcantly reduces losses. The antenna is excited from underneath the antenna by coupling RF energy from an open-circuited feedline through a slot in the ground-plane of the middle substrate layer. The feedline is shielded with another substrate layer which has a ground-plane on its opposite surface to mitigate the infuence of the structure on which the antenna is mounted. The antenna has the dimensions 12.3× 4.5 × 0.905 mm3 and operates across the 0.137–0.158THz band corresponding to a fractional bandwidth of 14.23%. Over this frequency range the average measured gain and efciency are 8.6 dBi and 77%, respectively. These characteristics makes the proposed antenna suitable for integration in sub-terahertz near-feld electronic systems such as radio frequency identifcation (RFID) devices with high spatial resolution.
Open Access
An antenna array utilizing slotted conductive slab: inspired by metasurface and defected ground plane techniques for flexible electronics and sensors operating in the millimeter-wave and terahertz spectrum
(Springer, 2023) Ali, Esraa Mousa; Alibakhshikenari, Mohammad; Virdee, Bal S.; Kouhalvandi, Lida; Livreri, Patrizia; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper describes an innovative design of an antenna array that is metamaterial inspired using sub-wavelength slots and defected ground structure (DGS) for operation over millimeter-wave and terahertz (THz) spectrum. The proposed antenna array consists of a 2 × 4 array of conductive boxes on which are implemented rectangular slots. The presence of dielectric slots introduces resonant modes within the structure. These resonant modes result in enhancing the electromagnetic fields within the slots, which radiate energy into free space. The resonant frequencies and radiation patterns depend on the specific geometry of the slots and the dielectric properties. The antenna array is excited through a single microstrip line. The radiating elements in the array are interconnected to each other with a microstrip line. Unwanted mutual coupling between the radiating elements can degrade the performance of the antenna. This was mitigated by defecting the ground plane with rectangular slots. It is shown that this technique can enhance the array¿s reflection coefficient over a wider bandwidth. The array was constructed on polyimide substrate having dielectric constant of 3.5 and thickness of 20 ¿m. The design was modelled, and its performance verified using an industry standard electromagnetic package by CST Studio Suite. The proposed array antenna has dimensions of 20 × 10 mm2 and operates between 80 and 200 GHz for radiation gain better than 4 dBi and efficiency above 55%. The peak radiation gain and efficiency are 7.5 dBi and 75% at 91 GHz, respectively. The operational frequency range of the array corresponds to a fractional bandwidth of 85.71%.
Open Access
Optical-microwave sensor for real-time measurement of water contamination in oil derivatives
(Elsevier, 2023) Abdulsattar, Rusul K.; Alibakhshikenari, Mohammad; Virdee, Bal S.; Sharma, Richa; Elwi, Taha A.; Kouhalvandi, Lida; Hassain, Zaid Abdul; Ali, Syed Mansoor; Türker Tokan, Nurhan; Livreri, Patrizia; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper presents a novel microwave sensor using optical activation for measuring in real-time the water contamination in crude oil or its derivatives. The sensor is constructed from an end-coupled microstrip resonator that is interconnected to two pairs of identical fractal structures based on Moore curves. Electromagnetic (EM) interaction between the fractal curves is mitigated using a T-shaped microstrip-stub to enhance the performance of the sensor. The gap in one pair of fractal curves is loaded with light dependent resistors (LDR) and the other pair with microwave chip capacitors. The chip capacitors were used to increase the EM coupling between the fractal gaps to realize a high Q-factor resonator that determines the sensitivity of the sensor. Empirical results presented here show that the insertion-loss of the sensor is affected by the change in LDR impedance when illuminated by light. This property is used to determine the amount of water contaminated oil. The sensitivity of the sensor was optimized using commercial 3D EM solver. The measurements were made by placing a 30 mm diameter petri dish holding the sample on top of the sensor. The petri dish was filled up to a height of 10 mm with the sample of water contaminated crude oil, and the measurements were done in the range between 0.76 GHz and 1.2 GHz. The Q-factor of the oil sample with no water contamination was 70 and the Q-factor declined to 20 for 100% contamination. The error in the measurements was less than 0.024%. The sensor has dimensions of 0.127λo × 0.127λo × 0.004 λo and represents a new modality. Compared to existing techniques, the proposed sensor is simple to use, readily portable and is more sensitive.
Open Access
Photonic controlled metasurface for intelligent antenna beam steering applications including 6G mobile communication systems
(Elsevier, 2023) Muqdad, Zainab S.; Alibakhshikenari, Mohammad; Elwi, Taha A.; Hassain, Zaid Abdul; Virdee, Bal S.; Sharma, Richa; Khan, Salahuddin; Türker Tokan, Nurhan; Livreri, Patrizia; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper presents a novel metasurface antenna whose radiation characteristics can be remotely controlled by optical means using PIN photodiodes. The proposed reconfigurable antenna is implemented using a single radiating element to minimize the size and complexity. The antenna is shown to exhibit a large impedance bandwidth and is capable of radiating energy in a specified direction. The proposed antenna consists of a standard rectangular patch on which is embedded an H-tree shaped fractal slot of order 3. The fractal slot is used to effectively reduce the physical size of the patch by 75 % and to enhance its impedance bandwidth. A metasurface layer is strategically placed above the patch radiator with a narrow air gap between the two. The metasurface layer is a lattice pattern of square framed rhombus ring shaped unit-cells that are interconnected by PIN photodiodes. The metasurface layer essentially acts like a superstrate when exposed to RF/microwave radiation. Placed below the patch antenna is a conductive layer that acts like a reflector to enhance the front-toback ratio by blocking radiation from the backside of the patch radiator. The patch’s main beam can be precisely controlled by photonically illuminating the metasurface layer. The antenna’s performance was modelled and analyzed with a commercial 3D electromagnetic solver. The antenna was fabricated on a standard dielectric substrate FR4 and has dimensions of 0.778λo × 0.778λo × 0.25λo mm3 , where λo is the wavelength of free space centered at 1.35 GHz. Measured results confirm the antenna’s performance. The antenna exhibits a wide fractional band of 55.5 % from 0.978 to 1.73 GHz for reflection-coefficient (S11) better than − 10 dB. It has a maximum gain of 9 dBi at 1.35 GHz with a maximum front-to-back ratio (F/B) of 21 dBi. The main beam can be steered in the elevation plane from − 24◦ to +24◦. The advantage of the proposed antenna is it does not require any mechanical movements or complicated electronic systems.
Open Access
Detection of signals in MC-CDMA using a novel iterative block decision feedback equalizer
(IEEE, 2022) Bagadi, Kalapraveen; Ravikumar, Chinthaginjala V.; Sathish, K.; Alibakhshikenari, Mohammad; Virdee, Bal S.; Kouhalvandi, Lida; Olan Núñez, Karen N.; Pau, Giovanni; See, Chan H.; Dayoub, Iyad; Livreri, Patrizia; Aïssa, Sonia; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper presents a technique to mitigate multiple access interference (MAI) in multicarrier code division multiple access (MC-CDMA) wireless communications systems. Although under normal circumstances the MC-CDMA system can achieve high spectral efficiency and resistance towards inter symbol interference (ISI) however when exposed to substantial nonlinear distortion the issue of MAI manifests. Such distortion results when the power amplifiers are driven into saturation or when the transmit signal experiences extreme adverse channel conditions. The proposed technique uses a modified iterative block decision feedback equalizer (IB-DFE) that uses a minimal mean square error (MMSE) receiver in the feed-forward path to nullify the residual interference from the IB-DFE receiver. The received signal is re-filtered in an iterative process to significantly improve the MC-CDMA system's performance. The effectiveness of the proposed modified IB-DFE technique in MC-CDMA systems has been analysed under various harsh nonlinear conditions, and the results of this analysis presented here confirm the effectiveness of the proposed technique to outperform conventional methodologies in terms of the bit error rate (BER) and lesser computational complexity.