2023 Regional Meeting - Abstracts & Speakers

The Art, Science and Engineering of Modern Antenna Measurements and Diagnostics: From Marconi’s First Measurements

This extended, four-hour “mini-course” presentation will provide the participants with a novel way to understand the fundamental concepts behind modern antenna measurements and, in particular, the near-field measurements and diagnostic techniques. Starting from Marconi’s first antenna pattern measurements, we then suggest planar near-field measurements as an educational paradigm linking electromagnetic theory, sampling techniques, and FFT. Starting from the basic electromagnetic principles, the underlying concepts governing simulations, designs and operations of planar-near field measurements and diagnostics techniques will be reviewed. Modern measurement schemes such as plane-polar and bi-polar scanning will be highlighted. Advances in applying these techniques to millimeter-wave measurements will be reviewed. Representative measurement results of reflector, array, reflectarray and lens antennas will be presented for diverse applications including planetary missions, radars for remote sensing, cubesats, etc. The importance of near field diagnostic techniques will be discussed through some unique test cases.  Finally, the topic of phaseless measurement techniques and algorithms will be touched upon demonstrating the potential applications of these techniques in modern antenna measurements. It is the intent of this educational tutorial to expose the participants to the fun world of antenna metrology, where they can get insights in a number of related fields.

Measurements and Modeling of 5G FR2 (> 24 GHz) Systems: Challenges, Observations, and Explanations Even Management Can Understand

5G systems are generating new measurement challenges.  Adaptive arrays can give time-varying patterns that may not be in the control of those tasked to measure them.  Base stations can still be electrically large (on the order of 30 to 50 cm), but wavelengths are getting smaller (around 1 cm and getting smaller). This means that the traditional far-field distance, or the minimum separation distance between a transmitter and receiver (where we think we have a good understanding of the field and pattern characteristics) can far exceed the dimensions of our current test facilities.  For example, a 30 cm base station has a rough far-field distance of 9 m, and a 50 cm base station can have a far-field distance of 25 m!  These results and problems are not new, but the proliferation of electrically large 5G phased array antennas has created new challenges for the measurement community which has grown used to performing measurements in traditional 3 m or 10 m chambers.  This will require investing in new larger chambers, shifting to near-field facilities where appropriate, or accepting the limitations inherent in measurements using traditional facilities.  In this presentation, we take a quick look at the challenges caused by 5G hardware, the options of larger chambers, the applicability of near-field facilities, and then focus on the tradeoffs associated with making measurements in the near-field of a transmitter or receiver.  To do this, we look at a few numerical models of antenna arrays and examine how pattern (or equivalent) characteristics change as the measurement distance is reduced.  Although not an exhaustive evaluation, this should show many of the issues related to measurements of electrically large antenna.

Antenna Simulation and the Dynamic Mission: A Case Study in Airborne Radar Altimeter and 5G Coexistence

Physics-based simulation, such as the finite element method (FEM), has been the cornerstone of antenna design for decades. As computational efficiency improves year over year, so has the demand on size and scale of applications. No longer is simulation of the isolated antenna adequate as vehicle integrators (aircraft, satellites, automobiles, etc.) expect full installed performance assessment via simulation as well. Thanks to myriad computational techniques and the resourcefulness of developers, hybrid methods enable enormous scale that include small RF components and antennas as well as interactions with the much-larger platform. This can be extended farther by including relevant features of the environment including terrain, buildings, and other objects and actors. Furthermore, the combination of installed antenna simulation with digital missions, such as a flight dynamic scenario, increases the fidelity and usefulness of the overall virtual prototype. In this presentation, we provide an overview of simulation techniques and demonstrate the first advantage of large-scale antenna simulations. Next, we demonstrate the power of digital mission engineering using the example of interference characterization and mitigation between a 5G base station and an airborne radar altimeter.

Dynamic Channel Emulation for Spacecraft Test and Integration

The manner in which path loss and Doppler shift change rapidly during the course of a satellite pass over an Earth station, and related effects associated with high frequency signal propagation through hydrometeors, is particularly challenging for satellite-based wireless communications systems. As part of projects sponsored by the Canadian Space Agency and European Space Agency, the UBC Radio Science Lab is developing channel models that support testing and assessment of: 1) 5G-based Non-Terrestrial Networks under realistic conditions, including account for handoff between satellites and terrestrial nodes, and 2) amateur-radio-based CubeSats. Here, we share the results of our efforts to take this work to the next level by developing a facility that uses an ETS- Lindgren GTEM cell to support over-the-air testing of small satellite communication systems using a custom-built dynamic channel emulator driven by STK and our own channel models.

Antenna Placement on Complex Platforms – Getting the Most from Measurements and Simulations

Measured antennas as field sources in numerical simulation is a consolidated method to investigate deployed antenna performance on large platforms. Typical applications are situations where a measurement or a full-wave simulation of the antenna and platform is either unfeasible or unavailable. Antenna placement on satellites are good examples of such an application. In these scenarios, the antennas are often supplied by a third party. Thus, the mechanical and electronic characteristics needed to create a full-wave model of the antenna are likely unavailable. To enable investigation of the antenna placement on a complex platform such as satellite or vehicle by standard Computational Electromagnetic (CEM) tools, the antenna can be fully characterized by a Huygens box derived from an equivalent current expansion of the measured antenna.

In this presentation, we will illustrate how the Huygens box representation is derived from measurement of the antenna and how the source representation is used in the full-wave simulation of the antenna and platform. The technique is illustrated and validated by measured examples.

Analyzing Ground-Based Electronically Steerable Arrays (ESA) Used for Communications with Non-Geo Stationary (NGSO) Satellites

Presenters: David R. Novotny & Leszek M. Langiewicz

The proliferation of planar phased array antennas that communicate with Low Earth Orbit (LEO) satellite constellations has unveiled potential measurement differences between fixed beam and scanning phased array antennas for assessing the time-averaged power density. Communicating with LEO satellites requires constant beam movement so exposure changes with time. Additionally, communications arrays, following Satellite Earth Stations and Systems (SES) regulations, are required to not transmit unless they are receiving enabling commands from a satellite – so blockages that stop communication and transmissions further reduce time-averaged power flux. These complex RF pattern, pointing, and operational modes leads to a proposed introduction of a spatial duty cycle that weighs time-averaged power density by the proportion of time the beam is on a target area. This presentation reviews a method to characterize the time-average power density and exposure from electrically large-phased arrays used for commercial LEO satellite communications in the near- and far-field.