Lightning electromagnetics

This project involved the determination of the effective radiated power of lightning sources and the polarization of the radiating source. This requires the computation of the antenna patterns at all the LDAR site receiving antennas. The known radiation patterns and RF signal levels measured at the antennas will be used to determine the effective radiated power of the lightning source. The azimuth and elevation patterns of the antennas in the LDAR system were computed using flight test data that was gathered specifically for this purpose. The results presented in this report deal with the azimuth patterns for all the antennas and the elevation patterns for three of the seven sites

Electromagnetic Cavity Effects from Transmitters Inside a Launch Vehicle Fairing

This paper provides insight into the difficult analytical issue for launch vehicles and spacecraft that has applicability outside of the launch industry. Radiation from spacecraft or launch vehicle antennas located within enclosures in the launch vehicle generates an electromagnetic environment that is difficult to accurately predict. This paper discusses the test results of power levels produced by a transmitter within a representative scaled vehicle fairing model and provides preliminary modeling results at the low end of the frequency test range using a commercial tool. Initially, the walls of the fairing are aluminum and later, layered with materials to simulate acoustic blanketing structures that are typical in payload fairings. The effects of these blanketing materials on the power levels within the fairing are examined

Evaluation of Lightning Induced Effects in a Graphite Composite Fairing Structure

Defining the electromagnetic environment inside a graphite composite fairing due to lightning is of interest to spacecraft developers. This paper is the first in a two part series and studies the shielding effectiveness of a graphite composite model fairing using derived equivalent properties. A frequency domain Method of Moments (MoM) model is developed and comparisons are made with shielding test results obtained using a vehicle-like composite fairing. The comparison results show that the analytical models can adequately predict the test results. Both measured and model data indicate that graphite composite fairings provide significant attenuation to magnetic fields as frequency increases. Diffusion effects are also discussed. Part 2 examines the time domain based effects through the development of a loop based induced field testing and a Transmission-Line-Matrix (TLM) model is developed in the time domain to study how the composite fairing affects lightning induced magnetic fields. Comparisons are made with shielding test results obtained using a vehicle-like composite fairing in the time domain. The comparison results show that the analytical models can adequately predict the test and industry results

Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This paper employees the Multilevel Fast Multipole Method (MLFMM) feature of a commercial electromagnetic tool to model the fairing electromagnetic environment in the presence of an internal transmitter. This work is an extension of the perfect electric conductor model that was used to represent the bare aluminum internal fairing cavity. This fairing model includes typical acoustic blanketing commonly used in vehicle fairings. Representative material models within FEKO were successfully used to simulate the test case

Mutual Coupling of Internal Transmit/Receive Pair in Launch Vehicle Fairing Model Using WIPL-D

Evaluating the fairing Radio Frequency (RF) Environment within the launch vehicle payload fairing cavity due to internal transmitters is an issue for the spacecraft and launch vehicle industry. This paper provides an effective approach for launch vehicle fairing evaluation of power reception and field distribution due to internal transmitters. A commercial electromagnetic computational tool, WIPL-D is applied in this study for test data comparison

Educational Activities Of The Ieee

A strategic objective of the Educational Activities Board (EAB) of the IEEE is the reshaping of educational programs to help members prepare for careers and employment in a rapidly changing technical arena. The Educational Activities Board works with IEEE Sections to promote an awareness of the available educational resources and in planning educational programs. The IEEE encourages the involvement of its members with their student branches, pre-college programs and in explaining the role of the engineer in the community. In addition to numerous technical conferences hosted by the IEEE at the national and international levels, many technical books and periodicals are available to keep members abreast with the latest advances in electrical engineering research. The IEEE has a collection of video tapes on technical topics, publishes the IEEE Standards and provides multi-media self study courses. This presentation will cover the educational activities mentioned above. In addition, specific activities of the Education Chapter of the IEEE Orlando Section will be presented

A Parametric Study On Performance Improvement Of A Tapered Slot Antenna

There are many medical applications that require antennas having high field penetration depth and a low profile. However, low profile/miniaturized antennas usually resonate at high frequencies, resulting in low penetration depths. Several studies have proposed the use of antennas with a coupling liquid for lowering the operating frequency of miniaturized antennas. However, immersing the antenna into a coupling liquid has some inherent drawbacks. In this work a parametric study has been carried out on a miniaturized tapered-slot antenna to improve its performance while eliminating the need of a coupling liquid. A dual-exponentially tapered antipodal slot antenna is proposed, which can provide a directional radiation pattern while also being compact

<title>Investigations on polarization schemes for use in wireless environments</title>

This paper presents a summary of polarization diversity schemes used in wireless communications. Results of various polarization schemes using dipoles, evaluated with respect to parameters such as SINR, mean effective gain, correlation coefficient etc. are presented. Analytical results show a noticeable improvement of the performance of the polarization diversity scheme when combined with the space diversity scheme