COFFEE Program Jump-Starts Integrable Filtering for Wideband Superiority
DARPA selects teams for COFFEE- COmpact Front-end Filters at the ElEment-level to sharpen focus on mitigating complex electromagnetic environment
The radio frequency (RF) spectrum environment is rapidly evolving.
DARPA wants to achieve superiority in electromagnetic spectrum (EMS) operations in the modern era.
This includes overwhelming adversaries gaining ground in the domain.
One area of priority: heightened multifunctionality and granular optimization in Active Electronically Scanned Arrays (AESAs).
An active electronically scanned array (AESA) is a type of phased array antenna, which is a computer-controlled array antenna in which the beam of radio waves can be electronically steered to point in different directions without moving the antenna.
This contrasts with a passive electronically scanned array (PESA), in which all the antenna elements are connected to a single transmitter and/or receiver through phase shifters under the control of the computer. AESA's main use is in radar, and these are known as active phased array radar (APAR).
AESA radars can spread their signal emissions across a wider range of frequencies, which makes them more difficult to detect over background noise, allowing ships and aircraft to radiate powerful radar signals while still remaining stealthy, as well as being more resistant to jamming. Hybrids can also be found, consisting of subarrays that individually resemble PESAs
DARPA’s allows for situational awareness and tactical communications. Unlike limited, narrowband phased array systems, wideband AESAs employ hundreds or thousands of tiny antenna elements that can all transmit and receive signals.
To help solve multifaceted and mounting challenges, DARPA has selected the research teams for the COmpact Front-end Filters at the ElEment-level (COFFEE) program, which seeks to create a new class of integrable, high-frequency filters with low loss, high-power handling, and seamless uniformity. The selected teams will be led by Northrop Grumman, Raytheon, Akoustis, BAE Systems, Metamagnetics, Georgia Institute of Technology, Columbia University, Carnegie Mellon University, University of Michigan, University of Texas at Austin and University of California at Los Angeles.
An AESA’s ability to dynamically reconfigure radar beams and communicate across a range of frequencies is especially important in congested environments.
COFFEE is key in military operations:
Resistance to signal jamming and interception
COFFEE is capable of:
- Visualizing, and
- Creating high-bandwidth data links for cross-domain operations
The COFFEE program will focus on creating an integrable filter technology to mitigate interference and maximize performance across a challenging S-band through Ku-band (i.e., 2 GHz to 18 GHz) frequency range, while physically bound within an 18 GHz half-wavelength array pitch (i.e., 69 mm2, a space smaller than a dime).
This new technology will account for digital-at-every-element advances – impacting hundreds or thousands of tiny antenna elements – for high-frequency systems.
COFFEE will increase bandwidths and digitization at the level of the individual element,” said Dr. Benjamin Griffin, the program manager.
The primary focus area of the program will leverage emerging microelectronics materials, integration, and design to build integrable filters, advancing new classes of miniaturized resonators as the building blocks. An additional, forward-looking focus area is oriented around millimeter-wave frequencies (demonstrating performance at 50 GHz), targeting fundamental limits of compact resonators beyond 18 GHz.
Potential biological effects of MMWs: thermal vs non-thermal effects
MMWs can induce rotation of some free molecules
Thermal effects appear after exposure. High-intensity MMWs act on human skin and cornea in a dose-dependent manner: heating sensation may occur at low-power densities, then followed by pain at higher exposures, and even by physical damage at very high powers. The active denial systems rely on this thermal effect. People exposed to high-power 94-GHz radiations undergo a sudden increase in their superficial temperature, resulting in a quick burning sensation and in an escape reaction from the MMW beam. It was demonstrated on human volunteers that the pain sensation was correlated with an increase in surface temperature.
There are also slight or moderate elevations of temperature are major issues for anyone interested in the biological effects of MMWs. There is existence of pure electromagnetic bio-effects, strictly independent on temperature rise.
Temperature elevation causes several effects at the cellular level.
It can impact cell growth, cell morphology and cell metabolism.
It can also induce the production of reactive oxygen species, increase DNA, lipid, and protein damages. All these parameters have often been highlighted in studies assessing the biological effects of electromagnetic fields. Exposures activate an adaptive mechanism called heat-shock response (HSR). During HSR, cells synthesize many proteins involved in protection and cell survival.
Among these proteins, the heat-shock protein 70 (HSP70) is dramatically over-expressed. Important property of MMWs is their shallow penetration depth into biological tissues and solutions. It is of the order of a few tenths of millimetres to several millimetres, depending on frequency and tissues, indicating that the skin or near-surface zones of the tissues are the main targets for MMW radiations. You may wonder how radiations with such a shallow penetration into the body can have biological effects at the level of the whole organism. However, it should be noted that skin is not isolated from the rest of the body, and this organ contains capillaries and nerve endings. So, it is possible that MMW bio-effects could be transmitted through secreted molecular factors by the skin or through the nervous system
Effect of millimetre waves on gene expression
Conditions affecting DNA, the so-called “genotoxic stresses”, include, for example, ultraviolet light, ultrasound and ionizing radiations, to which proteins are particularly resistant, while proteins are very sensitive to other physical conditions, such as hyperthermia and to certain chemical components, such as heavy metals. In fact, DNA damages seem to be induced by higher DNA, whose structure is relatively simple and whose principal deterioration consists of breaks of covalent bonds, the structure and solubility of proteins are conditioned by complex three-dimensional folding up, particularly fragile and affected by relatively weak amounts of disruptive treatments. Protein misfolding is very harmful for cells since it is inherently a self-propagating process, recruiting surrounding proteins by hydrophobic contacts, which may lead to deleterious protein aggregation.
Most of these were associated with proteotoxic and oxidative stresses, immune response, and tissue matrix turnover.
MMW exposure does not instantly activate transcription factors or stress-dependent signaling pathways, but we cannot rule out the existence of more subtle changes. For example, it is well known that environmental conditions (e.g., pollutants) may exert their long-term effects through epigenetic modifications. The epigenetic programs govern chromatin structure and remodeling, which permits a fine tuning of gene expression.
Effect of millimetre waves on cell proliferation and differentiation
Direct effect of MMWs on in vitro cell cultures.
An Italian group described an antiproliferative effect of 53–80 GHz irradiation under athermal conditions on different cell lines. In a first paper, they observed an inhibition of cell growth and morphological alterations.
Another study demonstrated enhancement of glucose metabolism associated with an increasing number of mitochondria.
In another study MMWs seem to induce or inhibit apoptosis, promote or not cell cycle progression, enhance or suppress cell.
Proliferation effects of chronic exposure at 50 GHz on the reproductive system of the rat . In sperm, they observed an increase in the percentage of apoptosis and a significant decrease in the transition phases of cell cycle in the exposed group. Their results are surprising because the authors performed their analysis on mature spermatozoids that are not supposed to divide anymore. However, their results globally point out toward an induction of oxidative damage to cells and an enhancement of the production of reactive oxygen species (ROS) in response to MMW exposure
Effect of millimetre waves on immune and inflammatory systems
Activation of immune system by MMW exposure could be indirect through stimulation of the peripheral neural system.
Biological effects of MMWs might be initiated by activation of free nerve endings in skin. Then, production of endogenous opioids may up-regulate the release of immunostimulatory cytokines from T-cells and macrophages (INF-γ and TNF-α). More recently, the link between endogenous opioids activation and immunomodulation effects of MMWs was confirmed.
Effect of millimetre waves on peripheral and central nervous systems
MMWs have been used for several medical applications notably pain release, such as treatment of headache, joint pain, postoperative pain, and painful diabetic neuropathy. MMWs are applied for 15–30 min andexperimental data showed that optimal effects were obtained with a frequency of 61.22 GHz
MMW exposure can directly impact nerve activity.
At the cellular level, cell permeability could be considered to explain nerve ending activation.
MMWs were already found to modify the plasma membrane bilayer structure.
The exact mechanisms of MMW action on membranes or biological systems remain unknown.
One can imagine that the MMW radiation can interfere with the orientation of charged and dipolar molecules, which can lead to changes at the membrane–water interface. If such a change modifies the neural membrane’s permeability, it could contribute to stimulate neuron endings or affect the electric signal transmitted to the rest of the body, then modify environmental perception, including pain sensation well-controlled and reproducible studies with an appropriate dosimetry are still needed to well characterize and quantify the biological effects of MMWs and their thresholds.
- R. Physique 14 (2013) 402–411
Contents lists available at SciVerse ScienceDirect
Comptes Rendus Physique
Electromagnetic fields: from dosimetry to human health
State of knowledge on biological effects at 40–60 GHz
“DARPA has been at the forefront of creating opportunities for multifunctional AESAs, with programs such as Arrays at Commercial Timescales (ACT) have implications in commercial mobile sector advances expected in the near future.”
The COFFEE program, which is expected to run for 50 months part of DARPA’s Electronics Resurgence Initiative (ERI) focused on revolutionizing communications for the 5G era and beyond. Research will kick off in the spring of 2022.
While the US strives for electronic supremacy it does so risking the health, safety, and well-being of its citizenry.
Celeste Solum is a broadcaster, author, former government, organic farmer and is trained in nursing and environmental medicine. Celeste chronicles the space and earth conditions that trigger the rise and fall of modern & ancient civilizations, calendars, and volatile economies. Cycles are converging, all pointing to a cataclysmic period between 2020 to 2050 in what many scientists believe is an Extinction Level Event.
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