Standard Gain Horn Research Articles

Preliminary Studies: Far-Field Microwave Dosimetric Measurements of a Full-Scale Model of Man

Measurements of microwave heating were made in a full-size, upright human model. The 75-Kg model, composed of electrically simulated muscle, was placed in the far-zone of a standard-gain horn inside an absorber-lined chamber. Pulsed energy at 1.29 GHz was obtained from a military radar transmitter (AN/TPS-1G) and produced radiation at 6-14 mW/cm2 average power density at the location of the model. Microwave heating at the front surface was measured at nine locations on the phantom. Measurements at several depths within the phantom were also made at a central location to gain information on the depth-of-penetration of the microwave energy. Results of the frontal surface measurements and of the penetration study permitted a calculation of the approximate whole-body average specific absorption rate (SAR) when the model's long axis was parallel to the E-field vector. For a normalized power density of 1 mW/cm2 at a frequency of 1.29 GHz, the whole-body average SAR approximated 0.03 W/Kg. This result agrees well with theoretical predictions based on absorption in prolate spheroidal models of man.

Testing of electronic industries association land-mobile communication antenna gain standards at the national bureau of standards

The Electronic Industries Association has a published standard, EIA RS-329A, "Minimum Standards for Land-Mobile Communications Antennas," Dec. 1975. This standard details the minimum performance requirements and the test methods for evaluating the performance of fixed and base station antennas at frequencies from 25-1000 MHz. Also included in this standard are the specifications for a set of standard antennas for use in various frequency bands. The EIA Antenna Committee, TR8.11, requested the National Bureau of Standards to calibrate the gain of some of these antenna standards. Two antennas were calibrated in the 450-512-MHz band, and two antennas in the 800-900 MHz band. This paper describes in detail the techniques used throughout the measurement program, the results, and the measurement uncertainties. Two basic methods of measuring the gain of the EIA antennas were employed during this calibration. The three-antenna technique was used at some frequencies, and the standard field technique was used at other frequencies. Both techniques are described. The NBS antennas used for the measurements were standard-gain pyramidal horn antennas. The antenna range used for the measurement is described. This is a vertical range using nonmetallic towers and hardware, thus providing essentially free-space conditions in which reflections and multipath problems are minimized. The measurements were made in terms of absolute power gain, i.e., referenced to an isotropic radiator. These results are discussed and also compared to the gain figures listed in EIA standard RS-329A.

Recent experimental results in near-field antenna measurements

Recent experimental results on determination of antenna pattern and power gain from near-field measurements are described. Two new antenna measurement theorems were applied. Measurements were made on an electrically large horn lens, a standard-gain horn and a nominal duplicate of the measuring antenna. Some comparisons with direct far-field measurement results were made.

Standard Gain Horns for Solar Calibration

The accuracy of the absolute value of solar flux depends on the temperature calibration techniques and the knowledge of the gain of the aerial used for the measurements. Recent advances in low-noise receivers, microwave components, and amplifier stability have reduced considerably the errors due to temperature calibration techniques. At present the knowledge of the gain of the aerial used for calibrations (usually a pyramidal horn) presents the largest source of doubt of an absolute calibration. Investigations of this problem suggest that a ‘standard gain horn’ should be employed at all observatories in absolute solar calibrations.