Logarithmic circuit with wide dynamic range

A circuit deriving an output voltage that is proportional to the logarithm of a dc input voltage susceptible to wide variations in amplitude includes a constant current source which forward biases a diode so that the diode operates in the exponential portion of its voltage versus current characteristic, above its saturation current. The constant current source includes first and second, cascaded feedback, dc operational amplifiers connected in negative feedback circuit. An input terminal of the first amplifier is responsive to the input voltage. A circuit shunting the first amplifier output terminal includes a resistor in series with the diode. The voltage across the resistor is sensed at the input of the second dc operational feedback amplifier. The current flowing through the resistor is proportional to the input voltage over the wide range of variations in amplitude of the input voltage

Openness to Diversity and Challenge: Assessment of Undergraduate Attitudes and Experiences in the College of Agriculture at Kansas State University.

This research used survey data to measure baseline levels of (1) openness to diversity and (2) diversity experience for students enrolled in the College of Agriculture at Kansas State University in Fall semester, 2004. The study also used regression analysis to identify and quantify the determinants of student openness to diversity and challenge and the level of experience with diversity. Regression results found that the determinants of openness to diversity and challenge included: experience with diversity, gender, size of hometown, enrolled credit hours, desire to obtain an advanced degree, outside work experience, and major field of study. Student experience with diversity was defined as a measure of the degree to which students have interacted with individuals who are different from themselves in race, ethnicity, philosophy of life, politics, religious beliefs, race, or a different country. The level of experience with diversity was found to be statistically associated with participation in courses and workshops in diversity, ethnicity, urban background, parent education levels, and desire to obtain an advanced degree, and major field of study. The major implication of the statistical results is that there is an opportunity to influence student openness to diversity and challenge, since: (1) experience with diversity was shown to be a highly statistically significant determinant of openness to diversity and challenge, and (2) the levels of diversity experience in the College of Agriculture were low. Therefore, enhanced programming for diversity appreciation and understanding as part of the university experience is likely to provide higher measurable levels of openness to diversity and challenge among students and graduates of the College. The identification of student characteristics associated with openness to diversity allows students, faculty, and administrators information useful for addressing the planning, implementation, and consequences of institutional diversity programming.Teaching/Communication/Extension/Profession,

The influence of polarization on millimeter wave propagation through rain

The influence of polarization on millimeter wave propagation is investigated from both an experimental and a theoretical viewpoint. First, previous theoretical and experimental work relating to the attenuation and depolarization of millimeter waves by rainfall is discussed. Considerable detail is included in the literature review. Next, a theoretical model is developed to predict the cross polarization level during rainfall from the path average rain rate and the scattered field from a single raindrop. Finally, data from the VPI and SU depolarization experiment are presented as verification of the new model, and a comparison is made with other theories and experiments. Aspects of the new model are: (1) spherical rather than plane waves are assumed, (2) the average drop diameter is used rather than a drop size distribution, and (3) it is simple enough so that the effect which changing one or more parameters has on the crosspolarization level is easily seen

The influence of polarization on millimeter wave propagation through rain

The measurement and analysis of the depolarization and attenuation that occur when millimeter wave radio signals propagate through rain are described. Progress was made in three major areas: the processing of recorded 1972 data, acquisition and processing of a large amount of 1973 data, and the development of a new theoretical model to predict rain cross polarization and attenuation. Each of these topics is described in detail along with radio frequency system design for cross polarization measurements

Lantana: Current Management Status and Future Prospects

Crop Production/Industries,

Polarization effects in millimeter wave propagation through rain: A review of present theory and a discussion of current experiments

An attempt was made to calculate the depolarization effects of rain on linearly or elliptically polarized millimeter waves. Results are given in graphs and tables

A depolarization and attenuation experiment using the COMSTAR and CTS satellites

Monthly statistical data are presented on ground rainfall rate and attenuation of satellite downlinks at 11.7 GHz, 19.04 GHz, and 28.56 GHz and on cross-polarization isolation at 11.7 GHz. Regression equations for relating isolation to attenuation, attenuation to rain rate, and attenuation at one frequency to attenuation at another frequency are also included. Longer-term statistics are also presented and discussed

A depolarization and attenuation experiment using the CTS satellite. Volume 1: Experiment description

An experiment for measuring precipitation attenuation and depolarization on the Communications Technology Satellite (CTS) 11.7 GHz downlink is described. Attenuation and depolarization of the signal received from the spacecraft is monitored on a 24 hour basis. Data is correlated with ground weather conditions. Theoretical models for millimeter wave propagation through rain are refined for maximum agreement with observed data. Techniques are developed for predicting and mimimizing the effects of rain scatter and depolarization on future satellite communication systems

A 20 Ghz Depolarization Experiment Using the ATS-6 Satellite

A depolarization experiment using the 20 GHz downlink from the ATS-6 satellite was described. The following subjects were covered: (1) an operational summary of the experiment, (2) a description of the equipment used with emphasis on improvements made to the signal processing receiver used with the ATS-5 satellite, (3) data on depolarization and attenuation in one snow storm and two rain storms at 45 deg elevation, (4) data on low angle propagation, (5) conclusions about depolarization on satellite paths, and (6) recommendations for the depolarization portion of the CTS experiment