AMTA Paper Archive


Welcome to the AMTA paper archive. Select a category, publication date or search by author.

(Note: Papers will always be listed by categories.  To see ALL of the papers meeting your search criteria select the "AMTA Paper Archive" category after performing your search.)


Search AMTA Paper Archive
    
    




Sort By:  Date Added   Publication Date   Title   Author

AMTA Paper Archive

Automated Ellipticity Measurements of Ultra-Wideband Circular Polarization Antennas
A. Maeda,T. Kobayashi, November 2005

This paper describes an automated ellipticity measurement system for ultra-wideband (UWB) circular-polarization antennas. The system comprises a double-ridged horn (DRH) antenna, a high-precision polarization rotator, an antenna-under-test (AUT) positioner, a vector network analyzer (VNA), and a controlling computer. The liner-polarized DRH antenna typically rotates 360° in 5°-intervals controlled by the rotator. At each angle, the VNA sweeps an ultra-wide bandwidth to measure the path gain. The least squares method was employed to find the axial ratio (r >= 1) and inclination angle at each frequency by fitting the plots to an anticipated peanut shell curve. Since the conventional cross polarization discrimination (XPD) has been defined for narrowband antennas, we proposed the wideband XPD as a frequency integration of the square of the circular polarization ratio (x), where x = (r + 1) / (r - 1), embracing a certain bandwidth. The wideband XPD represents the total power ratio between co- and cross-polarizations in the bandwidth. We measured the ellipticity and the wideband XPD of an axial-mode helical antenna using this system.

A Miniaturized L-Band Broadband Spiral Antenna on Ground Plane
M. Lee,C-C. Chen, J. Bolakis, Y. Tsang, November 2005

A strong interest exists in the commercial and military sectors for small and broadband antennas. For instance, in the automotive industry there is a need for a single antenna operating in the frequency range of 825-2500 MHz (AMPS, DAB, GPS, PCS, SDARS). For military applications, there is also a need to have a single aperture which permits operation in different communication bands and can be also used for imaging and guidance applications. These needs require wide band antennas, such as the miniaturized spiral antenna. In this paper we present the implementation of a spiral antenna situated on a ground plane that is fully functional at the size of 0.16 wavelength onward. Low profile (0.05 wavelength) and broadband operation design goals bring unique challenges, which must be confronted with multiple-front techniques. A combination of antenna geometry design and material loading results in the desired miniaturization effect. Further techniques, including the use of distributed resistors ensure good axial ratio and VSWR. Pattern uniformity and phase linearity of the antenna was also improved. In addition, we also examine the effectiveness of broadband spiral antenna miniaturization as a function of loading material’s dielectric constant.

A Novel Method for Antenna Gain and Phase Calibration
I. Gupta,C-C. Chen, E. Newman, J. Krieger, W. Burnside, November 2005

Standard Gain Horns (SGH) are normally used as reference antennas in antenna measurements. Gain charts for SGH are provided by the supplier. These charts give the gain of the SGH in dBi versus frequency but do not provide any information on the phase variations versus frequency. For complete antenna calibration, one needs the phase as well as gain data for SGH over the frequency band of interest. To obtain the gain and phase data, one can use the three-antenna method which requires three independent measurements and, therefore, is more susceptible to measurement errors. Note that if one has access to two identical antennas, the three-antenna method reduces to a single measurement which is more desirable. In practice, however, one does not have access to two identical antennas. In this paper, a novel method which mimics measurements with two identical antennas is described. In the method, one performs S11 type measurements on the antenna of interest by placing the antenna in front of a large conductive flat plate. The late term in the S11 measurements is then used to obtain the boresight gain and phase of the antenna under test. The measured gain and phase data of several antennas obtained using the proposed method is presented and compared with the results obtained using the three-antenna method as well as with analytical results.

3-D Antenna Measurement System - Low Gain Antenna Measurements and CTIA OTA Testing
D. Gray,J. Soong, November 2005

ABSTRACT We are in the era of wireless communications and devices. The antennas that enable these technologies are electrically small and can be challenging to test and analyze. Yet, the industry is becoming more standardized, and so too are the tests and certifications being adopted to validate these antennas. These antennas must undergo “antenna measurements” to characterize such information as far-field patterns and gain. Additionally, hand-held devices, such as cell phones, must satisfy requirements of the Over-the-Air (OTA) performance tests as specified by the Cellular Telecommunication and Internet Association (CTIA). These tests require a measurement system that can accurately collect data on a spherical surface enclosing the AUT. This system also has to provide the appropriate data analysis capabilities and has to be constructed from dielectric materials to minimize reflections.

A Two-Arch Antenna Measurement System
T. Laitinen,C. Icheln, J. Toivanen, November 2005

ABSTRACT A design of a spherical two-arch multi-probe antenna measurement system for measuring radiation patterns of mobile phones is presented. The proper functioning of the designed system is shown partly by computer simulations and partly by practical measurements with Rapid Antenna Measurements System (RAMS) at Helsinki University of Technology.

Active Measurements for CTIA Compliant Mobile Phones
S. Dreizin,R. Braun, Y. Shavit, November 2005

• Total Isotropic Sensitivity Power (TIS), which is an acceptable Bit Error rate at a certain incident cell power. • Total Radiated Power (TRP), which is the total transmission power of the Mobile station. These measurements may be performed using the Agilent 8960 or the Rhode and Schwarz CMU 200 Base Station (BS) simulators. All measurements are done in an anechoic chamber and OTA (Over the air). This paper will describe the measurements that are required in order to comply with the CTIA Certification program - Test requirements for performing Radiated RF Power and Receiver Performance measurements on mobile handsets. The paper will summarize the system configuration and the features of this integrated test system.

An Analysis of The Accuracy of Efficiency Measurements of Handset Antennas Using Far-field Radiation Patterns
I. Kadri,R. Thorpe, T, Palmer, November 2005

Radiation efficiency is an inherent property of an antenna that relates the net power accepted by an antenna to the total radiated power. It is especially useful for handset antennas where the radiation patterns are often of less use for comparing competing antennas. Radiation patterns though not as useful for direct comparisons, still provide one method by which efficiency can be calculated. To accurately calculate the efficiency from patterns, it becomes necessary to obtain multiple pattern measurements (cuts). A larger number of cuts whilst yielding more accurate efficiency results, significantly increase measurement time. Thus an antenna designer is often forced to trade off accuracy against measurement time since both quick and accurate measurements are desired. The focus of this paper is to quantify this trade off, in order to provide guidelines on the number of pattern measurements required for accurate efficiency results. Simulated and measured far-field radiation patterns are used and various numbers of cuts are utilized to quantify the loss in accuracy with a reduced number of cuts. The techniques outlined are geared primarily towards cellular handset antennas.

PID - 316 - A Hemi-Spherical Near-Field System for Automotive Antenna Testing
P. Betjes,D. Janse van Rensburg, D. Pototzki, November 2005

A hemi-spherical near-field test system with to be considered. This type of test system offers a added far-field capability is described. The facility has practical solution to the test problem in that combined been constructed for the characterization of automotive motion of a probe antenna and the object under test, antennas. The test system consists of an 11m tall allows for spherical data acquisition covering one half of dielectric gantry, a 6.5m diameter in-ground turntable and the spherical surface. The configuration also allowsa 28m-diameter radome enclosure. Special software integration of a conducting ground plane as well as a required to compensate for the reflectivity in the facility radome enclosure for weather protection andand the hemi-spherical truncation was developed and confidentiality. forms an integral part of this test system. The characteristics of this facility are described in this paper The characteristics of this newly developed and measured data is presented. facility are described in the following section of this paper.

Terminal Antenna Measurements with the Use of a Built-In Signal Source
P. Kabacik,A. Byndas, R. Hossa, November 2005

This paper presents the methodology we use to measure radiation patterns of small terminal antennas. The in-house developed measuring system is capable to record radiation patterns on the entire sphere and recorded values are not corrupted due to proximity of a large dual-axis positioner. As a feed cable had been identified as a primary factor modifying electrical properties of small antennas, we eliminated the feed cable at all by use of a built-in generator. Such generator is mounted back-to­back to the measured antenna. Most preferable the generator should be supplied with a battery, but use of a wired dc supply with a typical supplier is also acceptable in many instances. Such a concept of setup brings about many problems with providing a reference signal to an antenna receiver. Perhaps, firm operation of a reference channel is hard to accomplish without using advanced engineering means. Among them may be a switch with permanent power monitoring in its channels or an optoelectronic leg in the antenna microwave feed.

Local Oscillator Distribution Design Considerations for a Remote Mixing Antenna Test System
P. Kolesnikoff,B. Huang, e. Darnell, S. Hart, November 2005

Abstract Historically, most commercially available Local Oscillator (LO) distribution systems have used a closed loop control system to set LO power levels. As frequency switching times decrease, the time constant of the control loop can introduce errors to precision antenna measurements. This paper will discuss the basics of the remote mixing test system, and then discuss the limitations of various current approaches. Finally, it will introduce an open loop LO distribution system, and discuss the design considerations for the various components of the system.

Synthetic Aperture Radar Imaging Using a Unique Approach to Frequency-Modulated Continuous-Wave Radar Design
G. Charvat,L. Kempel, November 2005

A uniquely inexpensive solution to Frequency-Modulated Continuous-Wave (FMCW) radar was developed, using low cost Gunn oscillator based microwave transceiver modules. However these transceiver modules have stability problems causing them to be unsuitable for use in precise FMCW radar applications, when just one module is used. In order to overcome this problem, a unique radar solution was developed which uses a combination of 2 transceiver modules to create a precise FMCW radar system. This FMCW radar system was then used in a small Synthetic Aperture Radar (SAR) imaging system. The SAR imaging system was composed of a 12 foot long linear track to which the FMCW radar system was mounted. The FMCW radar system would traverse the linear track, acquiring data to be used for producing SAR imagery. The combination of the small aperture length, narrow bandwidth transmit chirp, and overall frequency instability of the FMCW radar system created a number of SAR imaging problems which were unique in this application. However, it was found that when these issues were properly addressed it was possible to create SAR imagery on a low budget.

Read Range Measurement and Analysis of 900 MHz-Band Radio Frequency Identification Systems Under Various Circumstances
Yongjim Kim,B-T. Yoon, S. Lee, Youngeil Kim, November 2005

The development of Radio Frequency Identification (RFID) system for tracking and controlling goods and products, and obtaining information from people and objects are growing very rapidly in modern telecommunication area. The read range is one of the most important key factors of the RFID system. The possible read range is decided by the system specifications, such as transmitted power, antenna gain, receiver sensitivity, etc. In this paper, the read ranges of a commercial RFID system with various antennas and measurement configurations in an anechoic room are measured. The read range of 900 MHz-band RFID is calculated and compared with the measured read range. Also, actual read range is strongly influenced by real operating circumstances. The measurement results are compared with the read ranges measured in indoor office environments.

Conducted Emissions Testing for Electromagnetic Compatibility
M. Moy,D. Arakaki, November 2005

Operating frequencies in the gigahertz range is creating an increased need for electromagnetic compatibility (EMC) testing. In the United States, FCC regulations require conformance to radiated and conducted emissions specifications. An EMC laboratory was established at Cal Poly San Luis Obispo (screen room, test instrumentation, and software) and an experiment was developed to explore conducted emissions effects. This paper will describe the test configuration, explain the calibration procedure needed to acquire accurate measurements, and illustrate measurement techniques applied to two example systems. In addition, the data collection process is illustrated through software donated by CKC Laboratories (EMC specialists). To verify the functionality of the laboratory and to assess measurement accuracy, two 12V/15W switching power supplies are characterized for conducted emissions performance; one as supplied by the vendor (KGCOMP) and a second unit with the EMC filters removed. The noise spectrum for both units are plotted against frequency and compared to FCC specifications. The unaltered unit is shown to be in compliance, thus verifying the accuracy of the test procedure and instrumentation.

Characterization of a Building Enclosing Microwave Source
V. Saavedra,B. Marchand, F. Oelhoffen, November 2005

CEA has developed a hyper frequency generator consisting of a high voltage one pulse power supply coupled with a Vircator capable of radiating a 1 GW electromagnetic field at 2 GHz, for 100 ns. The device is enclosed in a large building. It was first necessary to verify that the levels generated were below European safety levels on human exposure to radio-frequency electromagnetic fields. Measurements and calculations were performed for that purpose. Given the large dimensions of the building in comparison with the electromagnetic wave, the experimental hall was modeled by optical methods. A ray tracing program was written taking account of the field attenuation with distance and multiple wall paths with scattering reflections. The results were compared to those of an exact program dedicated to optics with diffuse back scatterings. Measurements were previously performed with a hyper frequency low power generator in the place of the Vircator. A mode converter enables the same electromagnetic field to be radiated (TM mode). This methodology enables the detection of any electromagnetic leakage in the building and its correction, and, finally, the validation of the facility, optimizing the number of measurements.

The Development of a Mini-UWB Antenna
B. Kramer,C. Chen, J. Volakis, November 2004

There is a great interest in the automotive and military sectors for small and broadband antennas that meet modern communication needs. These needs require ultra-wide bandwidth (>10:1) UWB antennas, such as the spiral antenna. However, the physical size at the low-frequency end typically becomes too large for practical applications. To reduce the size of the antenna, miniaturization techniques must be employed such as the use of high-contrast dielectric materials. Size reduction using high-contrast materials has been demonstrated for narrowband antennas, such as patch antennas, but not for broadband antennas to our knowledge. Therefore, the concept of miniaturizing a broadband spiral antenna using dielectric materials will be investigated experimentally and numerically. Issues that arise from dielectric loading such as impedance reduction will also be addressed. It will be shown using the results from these studies that there are practical limitations to the amount of miniaturization which can be achieved.

Design and Measurements of CPW-Fed Planar Ultra-Wideband Antenna
Y. Kim,D. Kwon, S. Lee, Y. Kim, November 2004

The frequency band 3.1 – 10.6 GHz has been opened for commercial use. Design and measurement of Ultra Wide Band (UWB) antennas in UWB communication systems are growing rapidly due to difficult requirements of UWB antennas such as small size, non-dispersiveness and ultra wide-band characteristics. In this paper, a CPW-fed planar ultra-wideband antenna is presented. Measurement results show that the radiation gain patterns are strongly influenced by the interaction signals between the antenna and the cable, especially at low frequency band. The performance of this antenna is also dependent on the leakage current along the cable. The antenna is mounted on various rectangular metal electronic devices such as DVD players or digital camcorder to investigate the interaction between the antenna and nearby metal objects. The antenna proves to be a good UWB antenna with broad radiation pattern, consistent gain and small group delay variation. The experiment shows that the performance of this antenna depends heavily on the cable interactions and the object that it is mounted on.

A Microstrip Leaky Wave Antenna and Its Properties
J. Radcliffe,G. Thiele, G. Zelinski, November 2004

It is well known that a microstrip transmission line can radiate if it is excited in its first higher order mode (with the fundamental or dominant mode suppressed). A new microstrip configuration is proposed that supports the first higher order mode while suppressing the fundamental mode. To quantify the leakage constants in the two cases for comparison purposes, several experimental means are considered to determine the source amplitude distribution from which the leakage constants may be deduced. First, an approximation to the source distribution is determined from the far field patterns themselves. Second, the source distribution is determined by carefully probing the near field. This paper uses these techniques to verify the performance of a new leaky wave antenna design.

Recent Advances in Impulse Radiating Antennas
E. Farr,L. Bowen, November 2004

We summarize here a number of advances in Impulse Radiating Antennas. These devices are composed of a reflector and a broadband feed. We have demonstrated improved gain and reduced crosspol by using feed arms located at ±30° to the vertical, as opposed to the original design that placed the arms at ±45°. We have reduced the return loss (flattened the TDR) at the splitter, at the feed point (focus), and at the resistors in the feed arms. We have added a ground plane that enhances mechanical stability and reduces crosspol. We have also improved the mechanical stability of the feed point.

Measured Characteristics of Zone Plate Antennas
J. Wiltse, November 2004

The Fresnel zone plate lens antenna has seen extensive investigation in the recent past, and has been used at frequencies from the microwave range through the millimeter-wave region to terahertz frequencies. For the usual zone plate antenna employed at these frequencies, path correction (i.e. phase adjustment) is accomplished by cutting different depths (grooves) in a dielectric plate or by using two or more dielectrics having different dielectric constants. Usually the focal length and aperture diameter are comparable, unlike the Fresnel zone plates which have been used at optical wavelengths. The planar configuration offers advantages of low cost, low loss, low weight, and ease of fabrication, while providing better performance, in some cases, than a true hyperboloidal or spherical lens or reflector antenna. Although the gain of the zone plate is normally less than that of a true lens, the reduced attenuation gives a greater overall system gain for the zone plate. Many measurements have been made to determine the antenna patterns (including beamwidth and sidelobe level), gain, efficiency, frequency dependence, focal behavior, aberrations, and bandwidth for both transmission and reflector designs. The major area of current debate is the question of efficiency as understood from analysis compared with actual measurements. This paper summarizes the parameters of zone plate antennas, and defines areas where more measurements are needed to fully describe their characteristics.

Blended Rolled Edge Reflector Design for the New Compact Range at MIT Lincoln Laboratory
T. Lee,A. Fenn, I. Gupta, W. Burnside, Somers., November 2004

Compact range reflectors, in general, are designed so that the parabolic section of the reflector is equal or larger in size than the desired quiet zone size. Next, proper edge treatment (serrated edge or blended rolled edge) is applied to the parabolic section to reduce the diffraction from the rim of the parabolic section in the quiet zone. With proper edge treatment, the reflector size can be bigger than the available space. Thus, there is a need to reduce the overall size of the reflector. In the case of blended rolled edge compact range reflectors, the total surface is a reflecting surface. Also, near the junction between the parabolic section and the edge rolled section, the surface is very close to the parabolic section. Thus, the fields reflected from this part of the reflector are nearly planar and can be used to increase the size of the quiet zone. This, in turn reduces the total size of the reflector. This concept has been applied to design a blended rolled edge reflector for MIT Lincoln Laboratory's new compact range. In this paper, the design approach will be presented and analytical performance of the reflector will be discussed. It will be shown that the over all performance of the reflector is better than the performance of the same size reflectors designed using the conventional approach.







help@amta.org
2024 Antenna Measurement Techniques Association. All Rights Reserved.
AMTA_logo_115x115.png
 
 

CONNECT WITH US


Calendar

S M T W T F S
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31