In this paper, the design challenges of E-band antennas are presented and the techniques to mitigate them are discussed with antenna design examples. At first, the limiting factors associated with high frequency connectors are discussed and compared with the ideal wave-ports on a coplanar waveguide (CPW) transmission line design. Then, the high frequency connector is integrated with the 60 GHz patch antenna. The advantages and disadvantages of using long and short CPW lines are also examined. The results are evaluated in terms of bandwidth constraints and effect on the radiation pattern of a 60 GHz antenna, highlighting the mitigation techniques.

Integrated Sensing and Communication (ISAC) couples radio sensing, data transmission, and control actions within a single closed-loop system. When Artificial Intelligence (AI)-driven policies adapt sensing and communication online across a variety of sensing tasks and objectives, end-to-end performance is shaped not only by waveform and channel conditions but also by inference latency, uncertainty, environmental dynamics, and hardware non-idealities, leading to fundamental trade-offs between sensing accuracy, communication reliability, and resource overhead. This manuscript presents a unified system architecture and evaluation methodology for AI-native ISAC, defined as ISAC in which learning-based agents adapt sensing, communication, and actuation policies online under uncertainty. We formalize the design space of closed-loop ISAC, propose a three-stage validation pipeline from bounds and feasibility analysis, through high-fidelity digital-twin simulation, to preliminary over-the-air validation, and provide a minimal reporting checklist that links technical Key Performance Indicators (KPIs) (e.g., data rate, SINR, target detection, parameter estimation, track quality, localization error, outage, latency, overhead, and energy per decision) to application-level Key Value Indicators (KVIs) (e.g., availability and mission effectiveness). Two representative instantiations, specifically Unmanned Aerial Vehicle (UAV)-based outdoor and Reconfigurable Intelligent Surface (RIS)-enabled indoor coverage extensions, are used to illustrate how to structure reproducible baselines and comparable evidence across heterogeneous deployments, helping bridge the gap between theoretical ISAC gains and deployment-ready performance claims.

This paper presents a spectrum-agile 60 GHz cognitive radio architecture that achieves a 94% reduction in idle power consumption via a hierarchical wake-up strategy. The system dynamically scales from a 4-element sparse sensing subarray (18.8 mW) to a 16-element verification mode, activating the full 64-element array only for confirmed communication. Key to this architecture is a mixer-first receiver fabricated in 22 nm Fully Depleted Silicon-On-Insulator (FDSOI) Complementary Metal-Oxide-Semiconductor (CMOS) that eliminates the Low Noise Amplifier (LNA) to prioritize frequency agility and power efficiency. The receiver achieves a measured conversion gain of >16 dB and an input return loss < −10 dB across the 57–64 GHz band, while consuming only 4.7 mW per element. System-level analysis using receiver performance metrics demonstrates that this topology meets regulatory detection thresholds, enabling practical, battery-constrained millimeter-wave (mmWave) Massive Multiple-Input Multiple-Output (mMIMO) deployments.

In this paper, we present the design, analysis, and experimental verification of a $4 \times 4$ integrated sensing and communication (ISAC) multiple-input multiple-output (MIMO) antenna for boresight applications. The main contributions include the derivation of general requirements for ISAC MIMO antennas, realization of an exemplary scalable MIMO array, incorporation of a defected ground structure (DGS) to reduce selfinterference and mutual coupling, and validation through fabrication and measurements. This work addresses the research gap of validated ISAC MIMO antennas meeting both application needs. A detailed comparison of antenna performance with and without DGS is also provided, alongside an evaluation of system-level suitability for future ISAC applications.

This paper presents an 18–24 GHz mixer-first receiver in 22 nm Fully Depleted Silicon-On-Insulator (FDSOI) Complementary Metal-Oxide-Semiconductor (CMOS) optimized for thermal and area constraints in dense Sixth Generation (6G) Frequency Range 3 (FR3) Extreme Multiple-Input Multiple-Output (xMIMO) arrays. The design achieves a measured conversion gain of 18.8 dB (1.5 dB variation), a simulated noise figure of 7.4–9.1 dB, and an Input 1 dB Compression Point (IP1dB) of −11 dBm to −8 dBm across the 18–24 GHz band, all within a 0.062 mm2 core area - a 90% reduction compared to state-of-the-art. By employing high-drive quadrature generation with centralized Local Oscillator (LO) distribution, the receiver consumes only 51 mW core power. The design demonstrates that balancing per-element compactness, linearity, and thermal efficiency through system-level architecture is essential for scalable dense xMIMO integration.

This paper provides a comprehensive near-field analysis of the 1-bit and 2-bit quantized passive AMC (PAMC) reflecting surfaces at 6.5 GHz. The evaluation is conducted across different near-field regions by varying the distance (d) between the source (a horn antenna) and reflecting surfaces optimized for reflecting at 30° reflection angle. The performance of the reflecting surface is assessed in terms of gain variance, main-beam stability and changes in the side-lobe levels (SLL) in an HFSS hybrid EM environment (FE-BI). The 1-bit design maintains its main beam direction across the near-field zones. However, gain drops were observed in the close proximity (d<250 mm) and in the far end of the near-field (d>350 mm). In contrast, the 2-bit design demonstrated better beam stability and higher performance in the near vicinity of the reflecting surface. On the other hand, when distance exceeds beyond 250 mm, the 2-bit design fails to preserve the desired beam with significant gain reduction. Due to its finer phase resolution, the 2-bit design showed improved SLL behavior and better gain performance over wider frequency bandwidth. These research findings provide fundamental insights into the near-field behavior of quantized PAMC and highlight critical considerations for optimal deployment of the reflecting intelligent surfaces (RIS) in the future dense 6G networks.

This work presents a dual-mode mmWave power amplifier (PA) with an integrated adaptive linearizer designed for Gearbox physical layer (PHY) systems, which demand hardware-aware energy optimization across diverse modulation gears. Fabricated in a 22nm FDSOI CMOS process for 53–63 GHz operation, the PA switches between high-gain (HG) and high-linearity (HL) modes to match the active gear requirements. Measurement results show that HL mode enhances output power at 1dB compression point (OP1dB) by 3.2 dB and corresponding power-added efficiency (PAE1dB) by 6.2%, maintaining linearity needed for spectral efficiency. The HG mode achieves a peak gain of 24.1 dB, reducing driver power requirements and enabling near-saturation operation for improved energy efficiency. The design consumes only 152 mW DC power and occupies a core area of 0.0749 mm2. System-level analysis demonstrates that this PA architecture supports the Gearbox-PHY objective of minimizing energy per bit while ensuring spectral efficiency.

In this paper a frequency reconfigurable down conversion mixer for the Frequency Range 3 (FR3) band targeting 7 GHz-16GHz is proposed. A step-by-step design, analysis and validation methodology for the mixer is presented towards sixth generation (6G) applications. This work was carried out in GlobalFoundries 22nm Fully Depleted Silicon-On-Insulator (FDSOI) technology. To implement the reconfigurability, a differential switch-capacitance network was integrated, where frequency switching was realized using a 4-bit code. Gilbert cell topology was chosen for the mixer core. The proposed mixer aims for 5 channels in the targeted FR3 band. The design was fabricated, and laboratory validation is performed through a Printed Circuit Board (PCB) packaging. Parasitics-compensated bondwire interconnects are developed for a low-loss and reflection-free chip-to-PCB interface. This design achieved the 9 GHz RF bandwidth while maintaining an overall conversion gain ranging from 5.9 dB to 9.4 dB at each individual channel. In terms of linearity, this work achieved an input 1-dB compression point ($I P_{1 d B}$) between −14.6 dBm to −11 dBm for the targeted channels. This mixer operates at 1.8V, and it has a power consumption of 23.58mW. The proposed design occupies an area of 0.56mm2 with I/O pads, whereas the mixer active area alone is only 0.1mm2.

Energy efficiency is a critical challenge for next-generation mobile networks. Especially as traffic demand grows, the energy per bit must decrease significantly. One promising solution is the Gearbox-PHY, which adaptively switches between modulation schemes and tailored radio front ends to maximize energy efficiency while delivering required data rates. In this regard, high spectral efficiency needs can be addressed with standard quadrature amplitude modulation, while low-power alternatives like impulse radio are employed for lower data rate scenarios, significantly reducing front end power consumption. While we considered the energy optimization for such a Gearbox-PHY in prior work, the specific focus of this paper is the consideration of the trade-off between oscillator power consumption and its phase noise. Using literature-based models and measurements for hardware power consumption, we demonstrate that embracing hardware impairments can lead to substantial energy savings of up to three orders of magnitude.

In this paper, co-located single-element aperture coupled antennas (ACA) working at the Wi-Fi frequency band are presented. The antenna shows an operating bandwidth of 320 MHz at 6.11 GHz center frequency and exhibits an isolation of 38 dB over the desired frequency band. The mutual coupling reduction is achieved by utilizing complementary split ring resonators (CSRR) in the ground plane and the integrated antennas show a smooth measured gain of 8 dBi in the entire working frequency band. Moreover, the co-located antennas are further integrated with the software-defined radio (SDR) to demonstrate its indoor sensing capabilities up to a distance of two meters. Simultaneously, the communication performance is shown and evaluated by employing a separated horn antenna receiver in a demonstrator designed for integrated sensing and communication (ISAC) applications.

Joint Communication and Sensing (JCAS) systems are emerging as a core technology for next-generation wireless systems due to the potential to achieve higher spectral efficiency, energy savings, and new services beyond communications. This paper provides a review of the state-of-the-art in JCAS systems by focusing on obtrusive passive sensing capabilities and inherent security and privacy challenges that arise from the integration of communication and sensing. From this point of view, we discuss existing techniques for mitigating security and privacy issues, as well as important aspects for the designing of secure and privacy-aware JCAS systems. Additionally, we discuss future research directions by emphasizing on new enabling technologies and their integration on JCAS systems along with their role in privacy and security aspects. We also discuss the required modifications to existing systems and the design of new systems with privacy and security awareness, where the challenging trade-offs between security, privacy and performance of the JCAS system must be considered.

The evolution of 6th generation (6G) wireless technology has become imperative due to the exponential growth of wireless devices and applications. In a macro-cellular scenario, the 6 GHz electromagnetic spectrum is projected to be the framework for 6G commencement. However, the main obstacles that inhibit their potential at the physical layer are the fabrication intricacies entailed in comprehending high port isolation ([Formula: see text]) and other key performance indicator (KPI) of compact printed multiple-input-multiple-output (MIMO) antennas. Subsequently, to overcome these impediments, six novel meander line-based MIMO antennas ([Formula: see text]) have been introduced for diverse 6G use cases, including internet of things, extended reality, artificial intelligence, vehicle-to-everything, unmanned aerial vehicle, and device-to-device integrated sensing and communications. Furthermore, two unique passive metamaterial structures of square ring (α) and shorting pins (κ) have been studied for attaining an electromagnetic bandgap (EBG). Their performance were investigated by means of numerical simulations and validated through measurements conducted within the anechoic chamber. Meticulous strategies for accomplishing impedance matching, circularly polarization (CP), and high [Formula: see text] values have been presented. Each of the proposed MIMO antennas employed dual radiators, a defected ground, and an EBG structure to exhibit [Formula: see text] of [Formula: see text]21 dB, quasi-isotropic CP, and other desirable KPI of MIMO antennas. Their assembly possessed a low-profile of 0.03 free-space wavelength ([Formula: see text]) and an area of 1.1[Formula: see text] × 1.1[Formula: see text], thus being preferable for cost-effective compact terminals. During the measurements, each prototype yielded one or more remarkable MIMO antenna KPI in the 6 GHz band. Particularly, [Formula: see text] enabled filtered bandwidth (BW) of 8.84% and modest gain (G) of 6.4 dBic, [Formula: see text] attained high G of 7.1 dBic and enhanced efficiency (η) of 87%, [Formula: see text] yielded high η of 94%, [Formula: see text] established notable radiation pattern with fair G of 5.8 dBic, [Formula: see text] provided filtered BW of 9.69% and prominent η of 93%, and [Formula: see text] featured wide axial ratio (AR-BW) of 60.63%. Furthermore, all antenna measurements demonstrated good MIMO performance with envelope correlation coefficient and diversity gain of <0.2 and ≈10 dB, respectively. The novelty of this work lies in the radiator and ground designs, as well as the accomplishment of numerous KPI that surpass state-of-the art MIMO antennas.

The upcoming generation of wireless systems is expected to integrate both communication and sensing capabilities by flexibly allocating resources, including hardware. Phased array antenna (PAA) systems are already vital in communication systems and radars and, therefore, have been intensively studied for several decades. Considering the availability of multiple review assessments for PAA implementation and signal processing, this article fills an existing gap by evaluating the hardware challenges and possibilities for sharing a PAA towards deployable integrated sensing and communication (ISAC) applications. Both types of applications impose tight and often divergent antenna-performance requirements, such as control over beam shape, scanning resolution, and side lobe tolerance. The inherent performance trade-offs, such as pencil beam for refined sensing versus broader beam for instantaneous coverage, highlight the complex design priorities that must be tailored to the application to achieve optimal joint system performance. This paper evaluates state-of-the-art antenna array structures and beamforming techniques in the context of ISAC systems. Although less popular due to their inherent limitations, passive beamforming networks are particularly highlighted for several proposed solutions, e.g., reciprocity and multibeam concept, and elaborated through a design and measurement by the authors. This article addresses the theoretical challenges that emerge while realizing a phased array out of a single element, their impact on sensing and communication performances, and finally, a summary of their mitigation techniques from the state-of-the-art. Selected simulation and measurement results from the authors support the discussions. The paper presents a set of PAA performance matrices for the ISAC system and their related joint benefits or trade-offs. The key enablers towards PAA sharing for ISAC systems, including quasi-circulator, gain-boosting lens, and electromagnetic bandgap structures, are presented, highlighting contemporary technological developments and related theoretical aspects. With the in-depth review, the authors also demonstrate proof of concept for the selected technologies through design steps, simulations, and measurements.

This hardware demonstration showcases a fully digital mono-static joint communication and sensing approach for multi-antenna arrays. Using a a software defined radio testbed consisting of two units transmitting and receiving standard communication waveforms in an in-band full duplex fashion over multiple antennas, it is shown that a range-angle radar image can be estimated from environmental scattering without impacting the communication performance. Such an approach can be key enabler for joint communication and sensing deployment using communication network infrastructure.

This paper introduces a reconfigurable radio frequency (RF) front-end based management of accuracy and other sensing key performance indicators (KPIs) as means for privacy control in the context of integrated sensing and communications (ISAC). Being part of the sensing devices (especially user equipments), the reconfigurable front-end would enable the users to control dynamically the sensing KPIs of their devices. This would allow the enablement of sensing-based applications while maintaining privacy and ensuring that the sensing application only receives the minimal amount of necessary sensing data. In this work, the use of RF front-end reconfigurability is highlighted for different types of systems and an architecture to integrate the controls in privacy-preserving User Equipments (UEs) is proposed. The active KPI management with RF front-end controls can be a key factor for the deployment of joint/integrated communication and sensing systems without causing a privacy nightmare in future sixth generation (6G) networks.

A printed cross-polarized dipole antenna, fed by a balun and placed inside a cylindrical cavity-like fixture, integrated with a dielectric lens is proposed in this work for joint communication and sensing (JC&S) applications. The proposed antenna may switch between horizontal, vertical, and circular polarizations, making it suitable for both communication and radar sensing. The design process and simulation results are presented, showing its potential for use in millimeter-wave and massive multiple-input multiple-output (MIMO) systems that combine communication and sensing.

Joint Communication and Radar Sensing (JCAS) is predicted to be one of the compelling features of future 6G systems. This paper presents a hardware-software evaluation platform designed to analyze JCAS performance in scenarios where multi-purpose receiver (RX) front-end, antennas, and waveforms are utilized to support both communication and sensing functionalities. The measurements are conducted in the 5G NR n258 band with 1GHz bandwidth. The front-end is tunable in gain, linearity, and frequency and is supported by a wideband high-isolation co-located aperture coupled antenna. The RX front-end has a peak gain of 29.9 dB and achieves a maximum iP(1dB) of -17.5dBm for a gain of 16.8 dB. The antennas provide an isolation of more than 40 dB across the operating band. The software platform supports several types of waveforms and modulation standards enabling a comprehensive performance evaluation. The paper also presents the radar measurements in a multi-target scenario along with communication measurements.

In-band full duplex (IBFD) is expected to be a key enabler for future communication systems and integrated sensing and communications (ISAC). However, achieving high transmitter to receiver isolation over a wide bandwidth poses a significant challenge in low-cost development and deployment of such systems. To address this challenge, in this work, a mm-wave wideband electrical balanced duplexer (EBD) for IBFD transceivers is designed and implemented. Over 40 dB isolation with 2.8 GHz simultaneous bandwidth is achieved covering a wide spectrum from 19 to 31 GHz targeting 5G mm-Wave FR2 and future FR3 bands for potential usage. The wideband transmitter to antenna response is achieved with only 4 dB loss. Antenna to receiver port loss varies from 4.5 to 7 dB. The EBD is implemented in $22-\text{nm}$ FDSOI process occupying 0.072 mm 2 area. To the best of authors knowledge, this is the highest reported usable measured fractional bandwidth for such a duplexer deployable for IBFD.

Integrated Sensing and Communication (ISAC) technology extends network functionality beyond communication by incorporating radar-like sensing, making it a crucial emerging technology for 6G. In addition to base station, User Equipment (UE) can also perform sensing in their surroundings and sensing data processing, contributing to the ISAC operations. However, UE introduces security and privacy risks due to their involvement in sensing activities, while being potential targets of various attacks at the same time. This paper first examines the UE architecture for ISAC, focusing on the key components involved in sensing, processing, and other related activities. Based on the roles of the components, deployment-specific interactions in resource allocation, and processing within sensing sessions, we identify potential security and privacy threats. To mitigate these risks, we recommend mechanisms that uphold key security and privacy properties, such as confidentiality, integrity, availability, reliability, data shielding, and protection of Personally Identifiable Information (PII) within the ISAC-enabled UE architecture.

This paper introduces a reconfigurable Gearbox transceiver architecture to address the heterogeneous requirements of sixth generation (6G) networks. Current designs are tailored for peak-performance use cases, and they lead to increased energy costs in low-data-rate scenarios that dominate cellular traffic. To overcome this inefficiency, we propose an adaptive radio frequency (RF) front-end in line with the previously established Gearbox physical layer (PHY) concept. The resulting system is designed to switch between high-performance and energy-efficient modes, reducing power consumption while supporting both communication and sensing services. Furthermore, the hardware’s reconfigurability allows for privacy-preserving operation by enabling controlled resource allocation. By jointly targeting energy efficiency, sensing capabilities, and privacy, this approach provides a promising foundation for sustainable and resilient 6G hardware design.