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This paper explores the accuracy capabilities of a two element phase interferometer measurement in a planar near-field scanner. Traditional phase interferometer applications utilize wide field of view antennas such as spirals making the utilization of planar near-field measurements less than ideal. In this application, high directivity antennas were utilized which allowed us to consider a planar near-field measurement solution. Leaving the AUT stationary and the stability of the planar near-field coordinate system were primary considerations in deciding to utilize a planar near-field measurement system. Typical interferometer performance metrics include comparing measured phase differences to ideal element phase differences at the same locations. Often the nominal drawing locations are used to generate the ideal element phase difference curves. The sensitivity of actual element vector displacement values versus ideal displacements can be reduced by deriving the best-fit displacement vector from the measured data and is utilized in the processing and reporting of results. This paper reviews the measurements, analysis techniques and results from this investigation and illustrates the capabilities of a planar near-field scanner to perform these types of measurements with a high degree of measurement fidelity.
The cost of quality is critical to all industrial processes including microwave device production. Microwave device production is often labor intensive and subject to many production defects. Early detection of these defects can markedly improve production quality and reduce cost. A novel approach to industrial defect detection has been demonstrated using a random noise radar (RNR), coupled with Radio Frequency Distinctive Native Attributes (RF-DNA) fingerprinting processing algorithms to non-destructively interrogate microwave devices. The RNR is uniquely suitable since it uses an Ultra Wideband (UWB) noise waveform as an active interrogation method that will not cause damage to sensitive microwave components and multiple RNRs can operate simultaneously in close proximity, allowing for significant parallelization of defect detection systems. The ability to classify defective microwave antennas and phased array elements (prior to RF system assembly) has been successfully demonstrated and presented at the 36th AMTA symposium. This paper expands on the prior research by focusing on the effects of altering interrogation signal characteristics to include operational bandwidth and signal frequency while actively interrogating similar antennas using an UWB noise signal. The focus of the experimental variation was to optimize classifier performance since unique device characteristics will be excited by various interrogation signal traits that can be exploited by the fingerprint generation and classifier algorithms. Experimentation with several typical UWB antennas and a phased array antenna is demonstrated. The effects of signal bandwidth on classifier performance on simulated fault conditions was performed using various antenna terminations and attenuators. Interrogation of the phased array was demonstrated using the array “backend” for signal down-conversion enabling a quick quality check control method with a simple back-end connection. The ability to wirelessly discriminate multiple fault conditions on individual phased array elements and discern phased array operational range of motion, both in pristine and heavy RFI environments is also shown. This method ensures that each produced phased array meets quality and operational requirements.
Coupling a Chip Antenna to an Antenna Measurement System is typically achieved using a co-planar micro-probe. This micro-probe is attached to a probe positioner that is used to maneuver the micro-probe into position and land it on the chip. Through this process, the chip is held by a chuck. Intentional and unintentional radiation from the Chip Antenna will interact with the micro-probe and chuck. From design conception, the antenna designer must take steps to reduce currents on the chip surface to minimize unintended radiation that will interact with both the measurement setup and the surrounding components of the final design. Even with good design practices, residual currents will still remain and radiate from the chip. Combined with intentional radiation from the chip antenna in the upper hemisphere, these radiated fields will impinge on the micro-probe and the probe positioner. Reflections from both the micro-probe and its positioner will reflect and generate interference patterns with the desired signal in the spherical measurement probe. In this paper, we evaluate, to first order, these effects by experimentation on two types of micro-probes (ACP & Infinity). The residual errors are then evaluated using modal filtering tools that further reduce these effects and the results are presented. Finally the dielectric chuck is modeled in simulation to evaluate the effects of the chuck on antenna patterns at 60 GHz and the results are presented.
Calibrating a passive, space-fed, phased array antenna is more difficult and time consuming then calibrating corporate-fed arrays because individual elements cannot be activated or deactivated. We will present our method of determining element state-phase curves and insertion phase bias between elements. We will also explain this method’s theoretical basis and validate it by comparing data measured in an anechoic chamber with data measured in a planar near field range. The anechoic chamber data will be compared with the typical, proven, but more time-consuming planar near field calibration method.
The design of active electronically steered arrays (AESA) is a challenging, time-consuming and costly endeavor. The design process becomes much more sophisticated in the case of dual-band circularly polarized active phased arrays, in which CP radiating elements at two different frequency bands occupy a common shared aperture. A design process that takes into account various inter-element and intra-element coupling effects at different frequency bands currently relies solely on computer simulations. The conventional near-field scanning systems have serious limitations for quantifying these coupling effects mainly due to the invasive nature of their metallic probes, which indeed act as receiving antennas and have to be placed far enough from the antenna under test (AUT) to avoid perturbing the latter’s near fields. In recent years, a unique, versatile, near-field mapping/scanning technique has been introduced that circumvents most of such measurement limitations thanks to the non-invasive nature of the optical probes. This technique uses the linear Pockels effect in certain electro-optic crystals to modulate the polarization state of a propagating optical beam with the RF electric field penetrating and present inside the crystal. In this paper, we will present near-field and far-field measurement data for a dual-band circularly polarized active phased array that operates at two different S and C bands: 2.1GHz and 4.8GHz. The array uses probe-fed, cross-shaped, patch antenna elements at the S-band and dual-slot-fed rectangular patch elements at the C-band. At each frequency band, the array works both as transmitting and receiving antennas. The antenna elements have been configured as scalable array tiles that are patched together to create larger apertures.
In this work, we measure the propagation losses for estimating the performance of a communication link in the frequency band of 300-350 GHz. The losses are measured by having a transmitter and receiver at varying distances upto 8.5 m. Due to limited ability to move the transmitter and receiver, reflection methods are employed. Using this simple method, we show the presence of water absorption lines in the spectra at 380 and 448 GHz. We also study the data-rate enhancement using dielectric lenses. Finally, using the measured data, we estimate that data-rates of 1 Gpbs for 8.5 m and 100 Gbps for 1 m distance are possible via a communication link at 350 GHz.
Recently, the Rapid Scatterometer (RapidScat) instrument was developed to sense ocean winds while being housed onboard the International Space Station (ISS). This latest addition to the ISS, launched and mounted in September 2014, significantly improves the detection and sensing capabilities of the current satellite constellation. The dual-beam Ku-band reflector antenna autonomously rotates at 18 rpm and acquires scientific data over a circular scan during typical ISS operations. Mounting such an antenna on the ISS, however, gives rise to many engineering challenges. An important consideration for any antenna onboard the ISS is the interference generated towards nearby ISS systems, space vehicles and humans due to the possible exposure to high RF power. To avoid this issue, this work aimed to characterize the antenna's absolute near-field distribution, whose knowledge was required for a blanker circuit design to shut off the RF power for certain time slots during the scan period. Computation of these absolute near-fields is not a straightforward task and can require extensive computational resources. The initial computation of those fields was done using GRASP; however, an independent validation of the GRASP results was necessary because of safety concerns. A customized plane wave spectrum back projection method was developed to recover the absolute electric field magnitudes from the knowledge of the measured far-field patterns. The customized technique exploits the rapid computation of the Fast Fourier Transform alongside the proper normalization. The procedure starts by scaling the normalized (measured or simulated) far-field patterns appropriately to manifest the desired total radiated power. This was followed by transforming the vectors into the desired rectangular coordinate system and interpolating those components onto a regularized spectral grid. The FFT of the resulting Plane Wave spectrum was properly scaled using the sampling lengths to determine the absolute near-field distributions. The procedure was initially validated by comparing the results with analytical aperture distributions with known far-field patterns. The properly normalized PWS approach was subsequently applied to the RapidScat Antenna using measured patterns from JPL’s cylindrical near-field range. The resulting near-fields compare quite well between the plane wave spectrum technique and GRASP, thus validating the calculations. This work provided significant enabling guidelines for the safe operation of the ISS-RapidScat instrument.
ABSTRACT Spherical near-field error analysis is extremely useful in allowing engineers to attain high confidence in antenna measurement results. NSI has authored numerous papers on automated error analysis and spherical geometry choice related to near field measurement results. Prior work primarily relied on comparison of processed results from two different spherical geometries: Theta-Phi (0 =?= 180, -180 = f = 180) and Azimuth-Phi (-180 =?= 180, 0 = f = 180). Both datasets place the probe at appropriate points about the antenna to measure two different full spheres of data; however probe-to-antenna orientation differs in the two cases. In particular, geometry relative to chamber walls is different and can be used to provide insight into scattering and its reduction. When a single measurement is made which allows both axes to rotate by 360 degrees both spheres are acquired in the same measurement (redundant). They can then be extracted separately in post-processing. In actual fact, once a redundant measurement is made, there are not just two different full spheres that can be extracted, but a continuum of different (though overlapping) spherical datasets that can be derived from the single measurement. For example, if the spherical sample density in Phi is 5 degrees, one can select 72 different full sphere datasets by shifting the start of the dataset in increments of 5 degrees and extracting the corresponding single-sphere subset. These spherical subsets can then be processed and compared to help evaluate system errors by observing the variation in gain, sidelobe, cross pol, etc. with the different subset selections. This paper will show the usefulness of this technique along with a number of real world examples in spherical near field chambers. Inspection of the results can be instructive in some cases to allow selection of the appropriate spherical subset that gives the best antenna pattern accuracy while avoiding the corrupting influence of certain chamber artifacts like lights, doors, positioner supports, etc. Keywords: Spherical Near-Field, Reflection Suppression, Scattering, MARS. REFERENCES Newell, A.C., "The effect of measurement geometry on alignment errors in spherical near-field measurements", AMTA 21st Annual Meeting & Symposium, Monterey, California, Oct. 1999. G. Hindman, A. Newell, “Spherical Near-Field Self-Comparison Measurements”, Proc. Antenna Measurement Techniques Association (AMTA) Annual Symp., 2004. G. Hindman, A. Newell, “Simplified Spherical Near-Field Accuracy Assessment”, Proc. Antenna Measurement Techniques Association (AMTA) Annual Symp., 2006. G. Hindman & A. Newell, “Mathematical Absorber Reflection Suppression (MARS) for Anechoic Chamber Evaluation and Improvement”, Proc. Antenna Measurement Techniques Association (AMTA) Annual Symp., 2008. Pelland, Ethier, Janse van Rensburg, McNamara, Shafai, Mishra, “Towards Routine Automated Error Assessment in Antenna Spherical Near-Field Measurements”, The Fourth European Conference on Antennas and Propagation (EuCAP 2010) Pelland, Hindman, “Advances in Automated Error Assessment of Spherical Near-Field Antenna Measurements”, The 7th European Conference on Antennas and Propagation (EuCAP 2013)
A guided-wave setup has been introduced for evaluating the high-power capability of the pyramidal absorbers. The details of the setup has been explained and its pros and cons has been noted. The major benefit of the proposed setup compared to the ones found in the literature is its need for lower amount of power when a pyramidal absorber is to be illuminated by a specific power density. That means, the high-power tests done using the proposed setup are cheaper compared to the tests performed with the setups formerly proposed in the literature.
Dual-calibration was first proposed by Chizever et al. in 1996 [AMTA'1996] and had get wide applications in evaluation of the uncertainty in radar cross section (RCS) measurement and calibration. In 2013, LaHaie proposed a new technique based on jointly minimizing the mean squared error (MMSE) [AMTA'2013] among the calibrated RCS of multiple calibration artifacts, which estimates both the calibration function and the calibration uncertainty for each artifact. MMSE greatly improves the estimation accuracy for the radar calibration function as well as results in lower residual and RCS calibration errors. This paper presents a modified version of LaHaie's MMSE by minimizing the weighted mean squared error (MWMSE) for RCS calibration processing from multiple calibrator measurements, which is related to the following functions and parameters: the calibration function; the theoretical and measured RCS; the number of calibration artifacts the number of frequency samples and the weight for ith calibration artifacts which may be defined in terms of the theoretical RCS of all the calibration artifacts. For example, if the weight is defined as the inverse of the total theoretical RCS of the ith calibration artifacts for all frequency samples, the error then represents the total relative calibration error instead of an absolute error as in MMSE. MWMSE then means that an optimal calibration function is found in terms of minimum total relative calibration error, which is expected for most applications. Numerical simulation results are presented to demonstrate the usefulness of the proposed technique.
At the Boeing 9-77 Range, we often encountered the need to support test objects of light to heavy weights with dielectric strings and fishing ropes of varying sizes from small to large. Unlike a metallic material, which reflects the waves from its surface, the dielectric material is a volume scatterer [1]. Usually, the radar echoes from the strings or ropes at broadside to the wave-front are the highest, then they fall off quickly with angles away from normal. In this paper we discuss several interesting cases learned, namely: a). To deduce the dielectric constant of a rope by the ratio of co-pol to x-pol echoes. b). To estimate the effective radius of a rope after being stretched under a heavy load. c). Observation of interference between two or more scatterers in the same scene. d). To process the angular dependent radar data of a tightly stretched rope as a field-probe along that rope. This paper is prepared in memory of and dedicated to a great teacher and friend on RCS [2]. ---------------------------------------------- ** Sam Wei is at: 4123 - 205th Ave. SE, Sammamish, WA 98075-9600. Email: paxwei3@gmail.com, Tel. (425) 392-0175 [1]. E. F. Knott, "Radar Cross Section Measurements," (Van Nostrand Reinhold, New York, 1993), Chapter 3, Target Support Structures, Section 3.2, String Supports, pp. 85-98. [2]. In Memoriam: Eugene Knott, IEEE Antennas and Propagation Magazine, vol. 56, No. 3, June 2014, pp. 132-133.
The smart plasma antenna based on opening and closing antenna windows to create antenna beam steering. It can steer 360 degrees in the azimuthal direction and 180 degrees in the z direction. The smart plasma antenna RFID reader can scan and read both passive and active RFID tags. Furthermore the smart plasma antenna is very compact compared to a phased array because plasma physics is used to steer and shape the antenna beam. The smart plasma antenna can easily fit in a small room where tags are to be read. It meets most SWaP criteria. The smart plasma antenna can have an omnidirectional metal antenna along the central axis such as a dipole or biconical antenna and is surrounded by a cylindrical ring of plasma tubes to shape and steer the antenna beam. The diameter of the smart plasma antenna is approximately one wavelength. When one of the plasma tubes has the plasma extinguished, it creates an aperture for the antenna beam. This is an open plasma window. The other plasma tubes are on with the plasma not extinguished. These plasma tubes with closed plasma windows protect the inside antenna from EMI. EMI is reflected from the closed plasma windows of the smart plasma antenna if the plasma density is high enough so that the plasma frequency is greater than the frequencies of the external EMI. The plasma frequency is proportional to the square root of the unbound electrons and is a measure of the amount of ionization of the plasma. If the inside antenna is a plasma antenna then not only is the beamwidth reconfigurable but the bandwidth is reconfigurable with a reconfigurable center line frequency. The reconfigurable bandwidth is equal to the difference in plasma frequencies from the inside plasma antenna and the plasma frequency of the outside cylindrical ring of plasma tubes. Thus by reconfiguring the relative plasma densities of the inside plasma antenna and the outside ring of plasma tubes, the bandwidth and centerline frequencies get reconfigured. This is useful in an RFID reading when some tags need to be read and others ignored through reconfigurable frequency filtering.
In the late 1990’s, Maloney et al. began investigating the design of highly pixelated apertures whose physical shape and size are optimized using genetic algorithms (GA) and full-wave computational electromagnetic simulation tools (i.e. FDTD) to best meet the required antenna performance specification; i.e. gain, bandwidth, polarization, pattern, etc. [1-3]. Visual inspection of the optimal designs showed that the metallic pixels formed many connected and disconnected fragments. Hence, they coined the term Fragmented Aperture Antennas for this new class of antennas. A detailed description of the Georgia Tech design approach is disclosed in [4]. Since then, other research groups have been successfully designing fragmented aperture antennas for other applications, see [5-6] for two examples. However, the original fragmented design approach suffers from two major deficiencies. First, the placement of pixels on a generalized, rectilinear grid leads to the problem of diagonal touching. That is, pixels that touch diagonally lead to poor measurement/model agreement. Other research groups are also grappling with this diagonal touching issue [7]. Second, the convergence in the GA stage of the design process is poor for high pixel count apertures (>>100). This paper will present solutions to both of these shortcomings. First, alternate approaches to the discretization of the aperture area that inherently avoid diagonal touching will be presented. Second, an improvement to the usual GA mutation step that improves convergence for large pixel count fragmented aperture designs will be presented. Over the last few years, the authors have been involved with developing the use of the focused beam measurement system to measure antenna properties such as gain and pattern [8]. A series of improved, fragmented aperture antenna designs will be measured with the Compass Tech Focused Beam System and compared with the design predictions to validate the designs. References: [1] J. G. Maloney, M. P. Kesler, P. H. Harms, T. L. Fountain and G. S. Smith, “The fragmented aperture antenna: FDTD analysis and measurement”, Proc. ICAP/JINA Conf. Antennas and Propagation, 2000, pg. 93. [2] J. G. Maloney, M. P. Kesler, L. M. Lust, L. N. Pringle, T. L. Fountain, and P. H. Harms, “Switched Fragmented Aperture Antennas”, in Proc. 2000 IEEE Antennas and Propagations Symposium, Salt Lake City, 2000, pp. 310-313. [3] P. Friederich, L. Pringle, L. Fountain, P. Harms, D. Denison, E. Kuster, S. Blalock, G. Smith, J. Maloney and M. Kesler, “A new class of broadband planar apertures,” Proc. 2001 Antenna Applications Symp, Sep 19, 2001, pp. 561-587. [4] J. G. Maloney, M. P. Kesler, P. H. Harms and G. S. Smith, “Fragmented aperture antennas and broadband antenna ground planes,” U. S. Patent # 6323809, Nov 27, 2001. [5] N. Herscovici, J. Ginn, T. Donisi, B. Tomasic, “A fragmented aperture-coupled microstrip antenna,” Proc. 2008 Antennas and Propagation Symp, July 2008, pp. 1-4. [6] B. Thors, H. Steyskal, H. Holter, “Broad-band fragmented aperture phased array element design using genetic algorithms,” IEEE Trans. Antennas Propagation, Vol. 53.10, 2005, pp. 3280-3287. [7] A. Ellgardt, P. Persson, “Characteristics of a broad-band wide-scan fragmented aperture phased array antenna”, EuCAP 2006, Nov 2006, pp. 1-5. [8] J. Maloney, J. Fraley, M. Habib, J. Schultz, K. C. Maloney, “Focused Beam Measurement of Antenna Gain Patterns”, AMTA, 2012
On-chip antennas operating at mm-wave frequencies have led to the development of spherical near-field test systems that allow the antenna to remain stationary [1]. These test systems, although simple conceptually, introduce very unique and challenging mechanical constraints. The approach taken by NSI is to construct a dual rotary stage articulating arm [2] design that moves the near-field probe on a spherical surface around the antenna. This structure experiences the gravitational force as a function of location angles theta & phi, resulting in structural deformation which is therefore variable. This further introduces radial distance variation of the probe. The unintended effect is therefore to introduce cross-coupling between the spherical near-field (SNF) position variables and this in turn perturbs the ideal spherical surface that is assumed. In this paper we describe the structural perturbation observed on such a scanner and assess to what extent this limits high frequency application for SNF testing. We also describe techniques to correct for radial distance variation and show how this extends the upper frequency limit of the system for SNF applications. We will present structural data acquired using a laser tracker and show to what extent these results differ for the two orthogonal spheres. It will be shown how angular positioning can be corrected for using a real-time controller. Measured RF results will be presented for the case of no radial distance correction and it will be shown how this can be addressed through post processing. An assessment of the suitability of the system for mm-wave testing will also be presented.
For high speed digital data connection such as WiMAX or WLAN, a good signal to noise ratio (S/N) is required. One way to keep up a good S/N-value while moving is the use of high gain antennas with a directive antenna beam. However, there is insufficient room to place high gain antennas in a vehicle. On top if this, it is becoming increasingly difficult and more packed in the car, so that progressive antenna approaches are enforced. As a vehicle can move towards and away from the transmitter site in any azimuth angle, the antenna shall offer some omni-directionality. In this paper, an antenna for 2.45 GHz WLAN is described which is very thin of 4 mm, offers 12 dBi antenna gain with almost omni-directional but very beneficial radiation characteristics with “rabbit-ear” shaped double-lobes. The flat antenna is easily implemented into the plastic spoiler on a hatchback vehicle. Experiments proof that this flat WLAN antenna structure in a spoiler outperforms monopoles and patch antennas on rooftop in any respect. When tuning to the right frequency, this antenna is ideally suited for Car2X-applications and Wireless Internet utilization such as WiMAX and WLAN.
This paper summarizes the design, fabrication and characterization of a coplanar waveguide fed modified aperture bowtie antenna operating in the 60 to 90 GHz range. Modifications to the bowtie edges extend the bandwidth up to 40% without increasing radiator area. The antenna was initially designed and measured in the 3-8 GHz frequency band and then frequency scaled to 60-90 GHz. The millimeter wave antenna is implemented on FR408 (er=3.65) and a multilayer laminate. Both substrates can be used in millimeter-wave system design where efficient antennas are needed. Return loss measurements of the antennas are made on a Cascade probe station. The results agree well with simulations in ANSYS HFSS. Until recently, only simulated radiation patterns were available illustrating broadside gain of 5 to 7 dB for these antennas. With the acquisition of a spherical scanner, near-field measurements have been taken of the three antennas from 67 to 110 GHz. The broadside radiation pattern results are compared with simulation. The NSI 700S-360 spherical near-field measurement system used in conjunction with an Agilent network analyzer, GGB Picoprobes and Cascade manipulator allow for on-wafer measurements of the antenna under test.
Current and future beam-steerable phased array antennas require broadband frequency range, multiple-beam operation and fast switching speeds. Near-field antenna testing is an efficient tool to rapidly and securely test antenna array performance, but many of the features of current and next-generation electronically steerable antennas require advances in near-field techniques so as to fully characterize and optimize advanced antenna arrays. For example, system requirements often dictate broadband frequency operation, which presents challenges in terms of probe antenna choices and probe-to-test antenna distances to properly characterize and optimize test antennas with a minimal number of scans and thus satisfy stringent customer requirements in a cost- and time-effective manner. Raytheon is developing near-field antenna test measurement techniques tailored to measure the radiation patterns of multiple beams over wide frequency ranges, to expand the range of test data collected for antenna optimization and customer review. Key test design considerations faced in developing advanced near field characterization techniques will be presented. Custom software to integrate antenna control with the near field measurement system is necessary to provide enhanced capability of characterizing multiple beams. Specialized data processing and analysis tools are needed to process thousands of datasets collected from a single scan, in a timely manner.
The US NEXRAD weather surveillance Doppler radar (WSR-88D) was recently upgraded to polarimetric capability. This upgrade permits identification of precipitation characteristics and type, thus providing the potential to significantly enhance the accuracy of radar estimated rainfall, or water equivalent in the case of frozen hydrometeors. However, optimal benefits are only achieved if errors induced by the radar hardware are properly accounted for through calibration. Hardware calibration is a critical element in delivering accurate meteorological information to the forecast and warning community. The calibration process must precisely measure the gain of the antenna, the Polarimetric bias of the antenna, and the overall gain and bias of the receive path. The absolute power measurement must be accurate to within 1 dB and the bias between the Polarimetric channels must be known to within 0.1 dB. These requirements drive a need for precise measurement of antenna characteristics. Engineers and scientists with the NEXRAD program employ solar scanning techniques to ascertain the absolute gain and bias of the 8.53 m parabolic center fed reflector antenna enclosed within a radome. They are also implementing use of daily serendipitous interference strobes from the sun to monitor system calibration. The sun is also used to adjust antenna gain and pedestal pointing accuracy. This paper reviews the methods in place and under development and identifies some of the challenges in achieving the necessary calibration accuracies.
After decades of international launches and varying space expeditions the low Earth orbit (LEO) has become littered with man-made objects and debris. With over 22,000 objects larger than a softball, and hundreds of thousands in smaller size existing, remediation efforts must take place to ensure the continuation of both collision free space flight and orbits. While smaller objects are difficult to track, and would consume more resources, the larger bodied debris offer a means to collect greater volumes of orbital debris clutter with less operations. In an effort to assist in the architectural design of microwave remote sensors, for the detection, tracking and identification of the large tumbling bodies, apriori knowledge of their relevant electromagnetic scattering parameters is essential. This paper work focus on the scattering phenomenology from possible large bodied orbital debris, such as rocket bodies, whose geometries are publically available. The results will strengthen existing data sets, Radar architectures, required signal processing, and even guidance navigation and control (GNC) routines that would be supported by resultant sensor information. Data products developed from commercially available electromagnetic simulation software will be presented, and the induced phenomenological scattering differences from the geometric variations between the possible targets will also be discussed.
Within RF measurement systems, engineers commonly wish to know how much phase ripple will be present in a signal based on a given signal-to-noise ratio (SNR). In a past AMTA paper (Measurement Considerations for Antenna Pattern Accuracy, AMTA 1997), John Swanstrom presented an equation which demonstrated how the bound on the phase error could be calculated from the peak SNR value. However, it can be shown that the Swanstrom bound is broken when the signal has a peak SNR value of less than approximately 15 dB. This paper introduces a new equation that bounds the maximum phase error of a signal based on the signal’s peak SNR value. The derivation of this new bound is presented, and comparisons are made between the old Swanstrom bound and the new bound. In addition, the inverse relationship (i.e., calculating the SNR value of a signal from phase-only measurements) is investigated. In the past, analytical equations for this relationship have been presented by authors such as Robert Dybdal (Coherent RF Error Statistics in IEEE Trans. on Microwave Theory and Techniques) and Jim P.Y. Lee (I/Q Demodulation of Radar Signals with Calibration and Filtering in a Defense Research Establishment Ottawa publication). The analytical equations for calculating the SNR value using phase-only measurements are reviewed and discussed, and a brand new numerical relationship based on a polynomial curve fitting technique is proposed.