Satheesh Bojja Venkatakrishnan

Florida International University | FIU · Department of Electrical and Computer Engineering

The upper mid-band -- roughly from 7 to 24 GHz -- has attracted considerable recent interest for new cellular services. This frequency range has vastly more spectrum than the highly congested bands below 7 GHz while offering more favorable propagation and coverage than the millimeter wave (mmWave) frequencies. Realizing the full potential of these...

Spectrum scarcity for wireless communication and data transfers has prompted interest to analyze interference among wireless links. As more bandwidth is utilized for communication links, there is a growing need to mitigate interference. By exploiting code division multiplexing (CDM) across an ultra-wideband (UWB) spectrum, it is possible to combat...

Wireless fully-passive neural recording systems are demonstrated with heterogeneous integration of sensing, mixing, and communication components in flexible polymer dielectric films. The recording neurosensor has an antenna, antiparallel diode, and a by-pass capacitor to modulate an incoming carrier signal with the neuropotentials and backscatter t...

A novel approach is presented and demonstrated for integrating a wideband vertically fed antenna array at Millimeter-Wave (mm-Wave) frequencies. Specifically, a novel cost-effective Antenna-In-Package (AiP) fabrication approach is presented, then a prototype operating from 55 GHz to 64 GHz is built while predicted performance is verified via measur...

Combining multiple-input and multiple-output (MIMO) with wideband in-band full-duplex (FD) channel access can improve the reliability, robustness, and spectral efficiency of wireless communications systems. FD antenna arrays also bring untold capabilities to multifunctional aperture arrays used in communications, radar, imaging, sensing, and electr...

A 4-channel code-multiplexed digital receiver is presented for multiple-input-multiple-output (MIMO) applications targeting 5G millimeter-wave (mm-Wave) communications. The receiver employs a code-multiplexing (CM) topology where multiple channels are encoded with unique orthogonal Walsh-Hadamard codes and multiplexed into a single-channel for digi...

Electrical activity recordings are critical for evaluating and understanding brain function. We present a novel wireless, implantable, and battery-free device, namely the Wireless Neurosensing System (WiNS), and for the first time, we evaluate multichannel recording capabilities in vivo. For a preliminary evaluation, we performed a benchtop experim...

Wireless fully-passive neural recording systems are demonstrated with heterogeneous integration of sensing, mixing and communication components in flexible polymer dielectric films. The recording neurosensor has an antenna, antiparallel diode, and a by-pass capacitor to modulate an incoming carrier signal with the neuropotentials and backscatter th...

To overcome the limited payload dedicated to onboard antennas for CubeSat/SmallSat applications, this paper presents a novel, foldable, dual-polarized Tightly Coupled Dipole Array (TCDA). In comparison to previous vertical feeds used for TCDAs, this array integrates a planar microstrip balun feed to enable foldability. The proposed array attains 5....

Communications at mm-wave frequencies and above rely heavily on beamforming antenna arrays. Typically, hundreds, if not thousands, of independent antenna channels are used to achieve high SNR for throughput and increased capacity. Using a dedicated ADC per antenna receiver is preferable but it’s not practical for very large arrays due to unreasonab...

To date, CubeSat radars and imagers have been limited to operations beyond S-band due to the challenges associated with the design of wideband, compact, low-frequency antennas. Concurrently, the frequencies at VHF/UHF bands can image through clouds and foliage, and are very attractive for ice, water and biomass sensing. There is thus a need to deve...

Today’s phased arrays require large instantaneous bandwidths, wide fields of view, and low profiles to conduct multiple functions. Many of these phased arrays rely on emerging high speed ADCs and advanced balanced transceivers. The benefits of balanced front-ends include improved linearity, dynamic range, isolation, and noise resilience. The applic...

Full-duplex (FD) antenna arrays are desirable for expanding the channel capacity of wireless systems up to 2, which is particularly important in the crowded sub-6-GHz spectral bands. Conventional FD solutions based on circulators do not scale to antenna arrays due to the presence of significant mutual coupling between antenna elements. This article...

Within the context of modern digital phased array (DPA) radios, differential Radio Frequency (RF) front-ends provide much greater immunity to noise and distortion by suppressing second order harmonics. Recent advancements in differential RF front-ends offer high dynamic range, high linearity, and low noise in the transceiver chain. However, a major...

A microwave planar log‐periodic dipole array (LPDA) antenna embroidered on textiles is presented for the first time. This antenna gives a 3.33:1 impedance bandwidth with 5 dBi average gain across the 0.9–3GHz band. This multi‐layer textile antenna employs a new denim stack‐up for repeatable measurements. The presented LPDA is tested under conformal...

We present an actively tuned balun to enable Simultaneous Transmit and Receive (STAR) antennas to achieve greater isolation. Specifically, for the first time, we propose placing a chip into the antenna feed to control the amplitude of the current density. Nearly perfect balance of the feed currents enables STAR antennas to maintain strong isolation...

Due to increased consumer demand for higher data rates, additional but discontinuous frequency bands will be allocated for commercial use. As a result, only a small percentage of the RF spectrum will be assigned to US departments and agencies. This spectrum shrinkage has led to the development of creative techniques for efficient spectrum utilizati...

Simultaneous transmit and receive (STAR) allows full-duplex operation of a radio, which leads to doubled capacity for a given bandwidth. A circulator with high-isolation between transmit and receive ports, and low-loss from the antenna to receive port is typically required for achieving STAR. Conventional circulators do not offer wideband performan...

With the growth of wireless data traffic, additional spectrum is required to meet consumer demands. Consequently, innovative approaches are needed for efficient management of the available limited spectrum. To double the achievable spectral efficiency, a transceiver can be designed to receive and transmit signals simultaneously (STAR) across the sa...

An extremely wideband (EWB) antenna array is presented that covers the UHF to $C$ -bands (0.13–6 GHz). The array has dual-linear polarization and is capable of wide-angle scanning. Notably, this array achieves a 46:1 contiguous impedance bandwidth at broadside with VSWR < 3.1 across most of the band and VSWR < 4 when scanning down to 60° in the E...

A novel deployable Inverted-Hat Monopole (IHM) antenna is presented for satellite applications. This frequency scalable antenna was designed and verified in the Very High Frequency (VHF) band (40-160 MHz) for 9U CubeSats and Ultra High Frequency (UHF) band (200-600 MHz) for 1U CubeSats. The VHF band ultra-wideband (UWB) monopole antenna operates fr...

The development of reconfigurable antennas compatible with a CubeSat form factor can aid several space missions. Often, satellite missions require multiple wireless links with the same radio, but the design of such antennas is challenging due to the mechanical constraints and the limited power aboard a CubeSat. In this article, we present a unique...

One-third of tonsillectomy patients experience post-operative taste disturbances (dysgeusia), yet the underlying cause is unknown. We hypothesize that unwanted radio-frequency (RF) energy couples to the metal-based mouth retractor during tonsillectomy and could be a possible cause of dysgeusia. To validate our hypothesis, in vitro studies are per...

Implantable systems are often employed to perform continuous high-resolution recordings of neural activity. These systems frequently require invasive procedures when implanting and maintaining effective operation. This causes major interruptions to daily life. Previous work demonstrated an in vitro minimum detectable signal (MDS) of 15 μV in amplit...

We present a novel hybrid beamforming architecture for high speed 5G technologies. The architecture combines several new concepts to achieve significant hardware and cost reduction for large antenna arrays. Specifically, we employ an on-site code division multiplexing scheme to group several antenna elements into a single analog-to-digital converte...

With the growing demand for spectrum utilization, the concept of full duplex transceivers has become attractive. These simultaneous transmit and receive systems (STAR) are attractive as they double bandwidth utilization. To realize STAR, we must suppress self-interference (SI) between the transmit and receive antennas. Doing this across a wide band...

Typical radio frequency (RF) digital beamformers can be highly complex. In addition to a suitable antenna array, they require numerous receiver chains, demodulators, data converter arrays, and digital signal processors. To recover and reconstruct the received signal, synchronization is required since the analog-to-digital converters (ADCs), digital...

Introduction: Endoscopy is the standard tool for the evaluation and treatment of gastrointestinal disorders. While the risk of complication is low, the use of energy devices can increase complications by 100-fold. The mechanism of increased injury and presence of stray energy is unknown. The purpose of the study was to determine if stray energy tr...

Ultra-wideband (UWB) system with digital beamforming allow for spatial filtering and multi user detection without degradation of the signal-to-noise ratio (SNR). Along these lines, we propose a novel onsite coding receiver (OSCR) architecture for digital beamforming that has already been verified to significantly reduce hardware requirement at the...

Digital beamformers combined with ultrawideband (UWB) antennas are essential for realizing cognitive and software defined radios. Concurrently, advances in digital technology and signal processing have drastically reduced digital beamforming complexity. Recently, a novel on-site coding receiver (OSCR) architecture was proposed to significantly redu...

Ultra-wideband (UWB) transceivers with digital beamforming are essential for realizing cognitive and software defined radios. Concurrently, advances in digital technology and signal processing have drastically reduced digital beamforming complexity. For example, a new on-site coding receiver (OSCR) architecture was proposed to significantly reduce...

Ultra-wideband (UWB) systems combined with the advances in digital signal processing and data handling have drastically reduced the complexity of cognitive and software defined radios. Therefore, techniques such as monopulsing, multiple beams, among others, can be implemented for phased arrays and Multiple Input Multiple Output (MIMO) systems. A ma...

Ultra-Wideband (UWB) systems are essential to realizing software defined and cognitive radios. Concurrently advancements in digital hardware and signal processing technologies have drastically reduced the realization complexity for such systems. Recently, a novel on-site coding receiver (OSCR) architecture was proposed to significantly reduce the i...

Recently, we proposed a code-modulated multipath receiver front-end to reduce the number of analog-to-digital converters (ADCs) behind antenna elements and realize significant area, cost, and power reduction. More specifically, code division multiplexing was implemented at the analog front-end for path combining into a single ADC. At the digital ba...

Recently, a novel class of on-site coding receivers was proposed. The architecture is suitable for digital beamforming in addition to offering multiple-input multiple-output capabilities. Essential to its realization is a code division multiplexing technique aggregating multiple signal paths at the analog front end into a single analog-to-digital c...

Ultra-wideband (UWB) systems with digital beam forming are essential to realizing cognitive and software defined radios. Concurrently, advances in digital signal processing hardware and algorithms have allowed for increased data rate handling, large memory blocks, and adaptivity. Therefore, these digital back-ends have drastically reduced the compl...