Introduction
Trends Toward Distributed Electronic Systems
The proliferation of existing processes made computation sufficiently cheap to allow scientists and engineers to focus on computational tools, theories, techniques, and systems that would previously have been infeasible. Although the possibilities offered by Moore's Law have diminished, today's scientists and engineers have an unprecedented breadth and depth of tools at their disposal.
Distributed Microwave Systems
With RFICs, distributed microwave systems (especially mobile phones, global positioning satellites, and wireless Internet) define life after the turn of the millennium. Phased arrays require a staggering amount of control to set phase, amplitude, frequency synthesis and modulation in each transceiver.
Thesis Outline
We note that in (3.5), the required delay for beamforming is given in terms of unwrapped phase𝛿𝑚. Note that 𝑘 =𝜔/𝑐, the required phase delay is a frequency dependent term. Using this expression allows the scalable router to operate as a programmable microwave mirror - the user can determine the direction in which reflections should be sent. The higher the amount of this power (contour level in Fig. 3.7), the more peripheral vision is present in the router system.
A programmable time delay within each branch unlocks system scalability—the main motivation for a scalable router. This is not the case for the CT core, as the CT path does not continue to process the signal when the input sampler switch is open - the output is actual. Given a fixed antenna pitch of 0.5𝜆, the power available to drive each element increases as the frequency drops.
14The model for a 2D phased array is very similar, and involves only changing the direction of the direction to a function of two variables (i.e. The resistance heater was used to increase the temperature of the electronics to 50◦C and dry ice placed around the exterior was used to reduce the temperature to -5◦ C. The MAPLE electronics functioned without problems over this range.
Microwave Array Fundamentals
Scalable Router
Purpose and Principles
System and circuit designers toiled to improve link budgets and achieve higher data rates and system capacities. Such scalable routers combine smaller spatially and electrically separated apertures to produce an effective large aperture at high data rates in a decentralized and dynamic manner.
Scalable Router Architecture
A critical feature of the scalable router is that each branch (receiver element connected to a transmit element) does not interface with other branches within the array. The scalable router architecture is well suited for integration into emerging mm-wave communications infrastructure.
System Analysis
Next is 𝛼, which is the ratio of one side of the relay gap to the total relay distance, 𝛼 = 𝑙. The added complexity of the scalable router does not necessarily translate into a substantial difference in cost.
Scalable Router Initial Prototype
The fine and medium controls change the phase of the clock that controls the output NOC. To illustrate the functionality of the router and the importance of real time delay for the scalable router, two digital configurations of the router were measured. The measurements with TTD clearly illustrate the tuned phase and group delay for all four branches, demonstrating the real possibility of adjusting the time delay of the branch circuit.
The transmitting antenna is 25 cm from the center of the expandable router, slightly offset below it. The receiving antenna (mounted on the linear scanner) is 55 cm from the center of the router.
Multiband Scalable Router
Concentrators are mounted on the same side of the four-layer RF flexible plate as the RFIC. The “constant curvature” line is shown dotted in blue in the center of the allowed area. 𝐸3(or𝐸3 . 0) is the input to the second stage of the shape reconstruction framework algorithm, discussed below.
Large Scale Flexible Arrays
Introduction
Increased aperture is one of the fundamental advantages of phased arrays over many other antennas.1 More aperture allows the array to concentrate more power in a narrower area. Radio frequency designs involve conductors whose size is comparable to that of the signal wavelength, almost by definition [127]. Some designs achieve omnidirectionality by using multiple antennas to cover directions blocked by the body of the spacecraft [27] [32].
2Several of the example antennas described in this subsection, as well as a review of other existing satellite antennas, can be found in [130]. Published space ESAs are non-deployable, meaning they are limited to openings smaller than the dimensions of the spacecraft's unused surfaces.
Caltech Space Solar Power Project
Despite the lofty aspirations of the concept, space solar energy systems must bow to economic reality. The reflection coefficient of the drive port for a single radiator versus frequency is shown in Fig. The solar cell design uses concentrator curtains mounted on the RFIC side of the flexible multilayer board, as shown in Fig.
Electrical and physical integration of the photovoltaics and concentrators takes place only on the RFIC side of the flexible board. Note that the majority of the thickness will likely be concentrated over the IC itself.
Flexible Array Shape Calibration
Accurate mapping of coupling measurements to the physical parameters of the array (PCM in Fig. 4.24) is essential for correct shape reconstruction. To isolate the spacing conditions, we perform a one-time calibration of the array in the fully flat configuration. Without a polarity, we make no assumption about the geometry and therefore do not include directionality in the model.
The accuracy of the shape reconstruction is measured by Δ𝑥, which is the average difference between the position of the reconstructed element and the. The shape reconstruction of the patch antennas is as accurate as the dipole reconstruction, with the exception of the most convex shape.
Introduction
Mission Opportunity
MAPLE will be placed in a sun-synchronous low-Earth orbit with ascending node local time3 and an altitude of approximately 500 km. A service is provided to space station crew members to attach payloads to the exterior of the station while providing power, uplink and downlink [131]. Notably, this is one of the few space missions that offers the opportunity to return cargo.
The launch provider will require the payload to pass a battery of tests to ensure that it will not interfere with the mechanical, thermal or electrical operation of the vehicle and other payloads present. The available downlink for MAPLE is <20 MB per day, shared with the other two co-hosted payloads of the Space Solar Power Project.
Project Planning
Despite its lack of flight heritage, the Arducam was compatible with the available voltages and digital interfaces of the SAMD21 motherboards. If aspects of the research phase are left until later in the project, the budget will increase as under-costs will grow, and the schedule will inevitably slip as the team waits for bids and outside firms slowly complete their tasks. MAPLE used three versions of the electronic hardware: first a desktop model for functional testing, then an engineering model (EM) used for environmental testing, and finally a flight model (FM).
If the base technology starts at 4+ TRL, previously built subsystems can be reused as part of the bench-top model. The board designer must purchase components and boards for at least one "extra" copy of EM.
Electrical Design
Once the prospective component is confirmed, sufficient quantity must be purchased for EM, FM and backups. The FM delivery date provides the launch provider with a point around which the schedule must be anchored. Once the components are selected, several design principles and techniques must be applied.
Redundancy adds complexity to board designs and adds time to development and testing, which must be taken into account as a trade-off. Although this philosophical approach is situational, it must be applied consistently when lowering component ratings.
Mechanical and Thermal Design of Circuit Boards
While the custom part and custom heater proved challenging, there are some conventional approaches that should be used on most models. A thick ground plane (2+ oz copper) and exposed conductor around the perimeter of the PCB help draw heat away from the board. Thermal epoxy can then be used to bond the PCB to the chassis frame, creating a wide, low thermal resistance path.
For multi-layer PCBs consisting of different substrate materials, the CTE must be matched to prevent traces from warping or warping at temperature extremes. In later versions of the board, the solder was expanded and moved further from the holes.
Space Environment
A mixture of Solithane 113 and Catalyst 300 with a weight ratio of 100/65 was used to create thermal bonds between the PCBs and the aluminum components where they are mounted. A mixture of Solithane 113, Catalyst 300 and CAB-O-SIL in a weight ratio of 100/74/10 was used for filling and encapsulating the components on the circuit boards. Before application, the parts must be pre-baked, and after application, the underfill must be dried at room temperature.
Whiskers (usually from very pure tin or zinc surfaces) are thin, crystalline strands that form over time. Leaded solder was used for all MAPLE components except for the custom radio frequency integrated circuits (RFICs).
MAPLE Qualification Testing
While sinusoidal vibration can be used to stress test a load, it is often used at low amplitude to identify system vibration modes. Even if components are rated for the mission temperature range, it is still important to verify their performance. The aforementioned tests were performed at ambient pressure due to the limitations of the thermal chamber available to the MAPLE team.
While the MAPLE frame could not fit inside, several of the payload PCBs were placed inside and configured for testing. The customized RFIC at the heart of the MAPLE experiment is manufactured in a 65nm process.
Regulatory
The MAPLE team chose to conduct limited SEE proton testing at the Texas A and M University (TAMU) Radiation Effects Facility. At TAMU, the components were tested with 48 MeV protons, which does not meet conservative NASA mission standards and does not meet the maximum energy particles that will be experienced during the MAPLE mission. Higher energy heavy ion testing was available at additional cost and logistical effort, but the MAPLE team's budget and schedule led to the decision to limit component testing to protons.
Successful applications to the FCC will also obtain permission from the International Telecommunication Union (ITU). The MAPLE team contracted an attorney to organize and submit our application to the FCC and assist in coordination with the host vehicle legal team.
Results and Conclusions
- Relaying scenario parameters
- Performance of IRS and scalable router for relaying scenarios
- Iterations of Spiral Match
- EDM Mask Matrix Structure Candidates
In: 2016 IEEE International Symposium on Antennas and Propagation and North American Radio Science meeting. In: 2015 IEEE International Symposium on Antennas and Propagation USNC/URSI National Radio Science Meeting. Degrees of freedom and maximum directivity of antennas: a limit on the maximum directivity of non-superreactive antennas. In:IEEE Antennas and Propagation Magazine pp.
In: 2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting. For Satellites Think Small, Dream Big: A Review of Recent Antenna Developments for CubeSats.” In: IEEE Antennas and Propagation Magazine p.
MAPLE Estimated Link Budget Quantities
Noise powers for given receive antenna noise temperature and band-
Price comparison for several COTS and space grade components
