2026 Regional Meeting - Abstracts & Speakers

Host for the 48th​ ​Annual​ ​Meeting​ ​and​ ​Symposium​ ​of​ ​the​ ​Antenna Measurement Techniques Association (AMTA)

Save the Date! Join us for the AMTA Regional Event in Austin, Texas, taking place June 1–2, 2026. This regional meeting will bring together researchers, engineers, and industry professionals working in antenna measurements, antenna design, and electromagnetic characterization to exchange ideas, share technical insights, and strengthen the AMTA community. The full-day meeting on June 1 at the AT&T Conferfence Center in downtown Austin will feature technical presentations, discussions on emerging antenna measurement techniques, an exhibition, and opportunities for networking and collaboration among academia, industry, and government laboratories. A half-day workshop on June 2 provides hands-on opportunities for live demonstrations in the Antenna and EMC labs at ETS-Lindgren in nearby Cedar Park, Texas. I hope to see you at the AMTA Regional Event!

Introduction to Leaky Waves and Leaky-Wave Antennas

A leaky-wave antenna (LWA) is a type of traveling-wave antenna where a guiding structure supports a leaky wave, i.e., wave that radiates (leaks power) as it propagates down the structure, forming a directive beam. The beam is conical in shape (or semi-conical, if there is a ground plane), becoming a fan beam at broadside. An array of LWAs can be used to create a pencil beam. Leaky-wave antennas offer a simple way to do beamforming, and hold promise and microwave, mmWave and THz frequencies.  The leaky wave is an interesting type of wave, which is “improper”, meaning exponentially increasing away from the guiding structure, when the wave is radiating in the forward direction. Furthermore, the wave is not always “physical”, meaning that it cannot always be physically excited by a practical source. When it is physical, and radiates into visible space, it can be used to make a simple highly-directive antenna. Leaky-wave antennas come in three general categories: uniform, quasi-uniform, and periodic. A uniform LWA has a uniform (i.e., constant) cross section and thus supports a guided wave with a single complex propagation wavenumber. An example would be an air-filled rectangular waveguide with a long longitudinal slot in one of its walls. This type of structure is usually designed to support a fast phase (where the phase velocity greater than that of light in free space) to enable efficient radiation. A periodic LWA radiates by virtue of a periodic set of perturbations along the guiding structure, which introduces an finite set of space harmonics (Floquet modes), where usually the n = -1 space harmonic is chosen to radiate. A quasi-uniform structure is one that is periodic, but here the period is small compared to a wavelength so that it radiates as a uniform structure where the fundamental (n = 0) space harmonic is the one that radiates. In all cases a load is typically used at the end of the LWA to absorb the residual power left in the leaky wave. 

For uniform and quasi-uniform LWAs, the beam is limited to the forward direction, i.e., between broadside and endfire, assuming that the antenna is fed at one end, which is the usual case. However, broadside beams can be achieved by feeding the LWA in the center, creating a bidirectional leaky wave. For a periodic LWA, a beam can be created in either the forward or backward directions. Furthermore, the beam scans with frequency, which can be advantageous for some applications. However, there is usually an “open stopband” at broadside that causes beam degradation as the beam is scanned through broadside. Techniques that can be used to overcome this problem will be discussed.  Simple design formulas can be obtained for LWAs to characterize the properties of beam angle, beamwidth, directivity, and pattern bandwidth. These formulas are useful and allow for a prediction of the optimum load efficiency to maximize the antenna gain, with the optimum load efficiency being close to 92% for relatively long LWAs.

A two-dimensional (2-D) LWA is one where a structure supports a radially-propagating leaky wave, excited by a central source. The Fabry-Pérot resonant cavity antenna is the most common example of such a LWA, where a partially reflecting surface (PRS) is placed above a grounded substrate (which may be air). This type of LWA can produce a symmetrical pencil beam at broadside, or a conical beam that is scanned to some angle from the vertical axis. Leaky-wave theory and design principles can be extended to this important class of antennas

Introduction to Antenna Measurements: Antenna Range Selection and Standard Recommendations

IEEE Std 149-2021 provides a comprehensive framework for engineers beginning work in antenna measurements, offering standardized guidance on best practices and measurement methodologies. This presentation introduces the fundamentals of antenna measurements by following the key recommendations and procedures described in the IEEE standard. The talk discusses how to properly select an appropriate measurement range, including considerations between near-field, far-field, and compact ranges depending on the antenna size, frequency, and required accuracy. In addition, the presentation reviews important aspects of the measurement system architecture, including both RF instrumentation (sources, receivers, and calibration procedures) and mechanical positioning systems used to ensure accurate antenna alignment and pattern acquisition. A brief overview of antenna gain measurements is also provided, highlighting commonly used techniques such as comparison methods and reference antennas. Finally, the presentation introduces the concept of measurement uncertainty, providing a practical example of how uncertainty can be estimated and quantified in antenna measurements following IEEE guidelines. The goal of this talk is to give engineers and students a clear and practical starting point for implementing reliable antenna measurement procedures while emphasizing the importance of standardized practices to ensure repeatability and measurement confidence. 

Acceleration of Antenna Measurements using Compressive Sensing and Sparse Sampling

Antenna measurement applications traditionally rely on extensive sampling to characterize performance, often resulting in prolonged test times and increased operational complexity. This paper explores the integration of compressive sensing and sparse sampling techniques to revolutionize antenna testing methodologies. By leveraging the inherent sparsity of antenna radiation patterns in appropriate transform domains, these approaches can significantly reduce the number of required measurements while maintaining or enhancing data fidelity. We demonstrate that compressive sensing enables efficient reconstruction of antenna patterns from under sampled datasets, leading to decreased test durations and lower resource demands particularly in production test environments. Furthermore, the proposed framework improves fault detection accuracy by amplifying the sensitivity to anomalies in sparse representations, allowing for earlier identification of defects. Simulation and experimental results validate the efficacy of these techniques across various measurement scenarios, showcasing reductions in test time by up to 60%. This work highlights the transformative potential of compressive sensing and sparse sampling for next-generation antenna measurement systems, offering a scalable and robust solution for both laboratory and field applications.

Measuring S-Parameters and Power with Uncertainty

Scientists have been investigating uncertainty in microwave measurements and have proposed models and techniques to quantify the individual contributions.   These contributions can be systematically determined and added as part of a measurement, for small-signal S-parameters as well as large-signal power measurements.  This empowers design engineers, test engineers and technicians, metrologists and production managers to report performance with uncertainties, and give the confidence needed to ensure product performance over time.  This lecture introduces the theory and implementation of measuring S-parameters and power with uncertainty, and shows the effects of common components on the uncertainty in these measurements.  Participants will leave this lecture with the knowledge required to understand and measure S-parameters and power taking into account measurement uncertainties.  They will also learn best-practices that can help reduce measurement uncertainty in order to gain a higher confidence in their own measurements.  Participants should be able to take this knowledge back to their employers and improve their own processes accordingly.

Advancements in Antenna Far-Field Gain Extrapolation Calibration

The antenna extrapolation calibration method is widely recognized as one of the most precise techniques for calibrating antenna far-field gain and is extensively utilized by metrology institutes globally. Originating in the 1970s at the National Bureau of Standards in the USA (now NIST), this method is grounded in the generalized transmission equation—a formulation that extends Friis' transmission formula by incorporating additional nearfield and antenna coupling terms. These equations, derived from Maxwell's equations, progress from wave equations to transmission equations, providing a comprehensive response formula between two antennas in free space as a function of distance.  In practical applications, antenna responses are measured across distances, and through post-processing and curve fitting, antenna far-field gain is extrapolated from these nearfield measurements, typically conducted within an anechoic chamber. This presentation explores recent advancements in post-processing techniques, leveraging state-of-the-art mathematical tools such as empirical mode decomposition, k-space filtering, and compressive sensing. These advancements are aimed at mitigating reflections in the environment, thereby enhancing the accuracy of far-field calibration.

Real World Challenges with Antenna Calibration in the Aerospace Industry

EMC emissions and immunity measurements require the characterization of antennas at reduced distances. Antenna-to-antenna interactions present during calibration, may not be present during measurements and may introduce significant errors. Aircraft High Intensity Radiated Field (HIRF) susceptibility measurements require the antennas be characterized in the far-field. Reference measurements must also be taken on-site and require the removal of ground reflections. Time domain techniques can be employed in both these cases but require antennas with good time domain response.  Unique Transverse Electromagnetic (TEM) antennas were developed to allow time domain gaiting. TEM antennas are simple, inexpensive and well-suited for time domain applications due to their low aperture reflections and clean time domain response.