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The paper describes a simple but unique antenna test facility suitable for aerospace antenna developments. The total idea can be easily adopted by organizations who wish to carry out antenna measurements with minimum required instrumentation. The facility majorly caters for omni and wide beam antenna measurements, has been set up at ISRO Satellite Centre, Bangalore, India. It has been extensively used for omnidirectional antenna developments in VHF, UHF, L, S, and X-bands for India’s various space programs. Radiation pattern, gain, polarization and impedance measurements can be carried out both in near free space conditions as well as the ground reflection modes. The main feature of the facility is the use of large fiber-glass mounting structures for avoiding reflections and perturbations in radiation patterns due to impressed surface currents, specially in VHF ranges. Field probing is done by the use of a fiber-glass X-Y probe positioner. The facility used Scientific Atlanta 1752 Receiver and 1540 Recorder. Suitable software has been added to the facility for contour plotting of radiation levels, calculation of efficiency isotropy, and polarization properties.
In recent years there has been an increasing requirement for more extensive and precise measurements of the polarization properties of antennas. Some of the more conventional polarization measurement techniques are no longer applicable because of the required measurement time or the achievable accuracy. This presentation is an overview of polarization measurement methods which may be employed on far-field antenna ranges. Instrumentation requirements and sources of error are also included.
The Defense Electronic Supply Center in Dayton, Ohio has recently issued a specification, MIL-A-87136, for testing Airborne Antennas. This specification covers all aspects of testing antennas including a section dealing specifically with radiation pattern tests. Further, this specification defines the data format to be used when antenna pattern measurement data is required to be furnished on magnetic tape. Scientific-Atlanta’s Series 2030 Antenna Data Collection System’s magnetic tape format and test instrumentation meets the requirements set forth in MIL-A-87136. The system is a complete instrumentation/firmware package designed and programmed to perform commonly made antenna pattern measurements. After initial operator set-up, measurements can be made automatically at frequencies in the 1-18 GHz range. The test results are digitally recorded on magnetic tape and may be displayed as radiation distribution plots, data listings, or as conventional data patterns. The presentation describes the Antenna Data Collection System, its application to automatic antenna testing and to the requirements of MIL-A-87136. Features of the Data Collection System are included, as well as advantages of automatic measurement and digital recording of antenna data.
This paper will present a basic explanation of the IEEE Standard 488-1978, concerning what it is, and how and why it concerns people in the RF world. In addition, the practical side of the IEEE 488 will be discussed, touching on such topics as the types of instrumentation available with IEEE, custom systems design and installation, the new one-chip interfaces, computer enhancement of measurements and generation of analytical graphic data. This up dated review is made with an eye towards enhancing both speed and accuracy of contemporary antenna testing techniques.
Methods of remotely controlling source transmitters and antennas over long distances is described. The remote range controller instrumentation currently available is limited to a 5.5 mile separation, over voice grade telephone lines. Unfortunately the phone line routes are not line of sight. In fact, the most direct route available for source control over dedicated phone lines at the Westinghouse antenna range complex is 13 miles in length. We wanted to utilize the Scientific Atlanta Model 4580 Remote Range Controller since it is fully compatible with out existing signal sources, programmable receivers and positioner controls. However, the data set available with the Model 4580 is limited to 5.5 miles separation between the master control unit and the remote control unit. The data set requires four wires or two dedicated phone lines. Transfer speed is 0-9600 bits per second asynchronous. The solution to overcome the 5.5 mile limitation and permit full use of the Model 4580 capabilities is described. Lightning protection and alternate control methods using tone controls over phone lines and method of employing a microwave link is discussed.