Dry air, water vapor, hydrometeors, and other particulates (sand, dust, aerosols, and volcanic ash) in the atmosphere introduce microwave propagation delays. These delays must be properly characterized to achieve the highest accuracy in surveying and atmospheric sensing using Global Positioning System (GPS) signals. In this paper we review the theory of microwave propagation delays induced by t...

This work presents new method, retrieved results and validation for complex and frequency dependent permittivity and permeability parameter extraction of two composite, homogeneous and isotropic magnetically loaded microwave absorbers. Permittivities and permeabilities are extracted from free space transmission measurements for frequencies from 22 up to 140 GHz. For validation of the results re...

This paper develops a novel relationship between azimuthal distribution of multipath power and narrowband small-scale fading characteristics. The fundamental relationship is useful for studying adaptive arrays, smart antennas, equalization, diversity, and any other wireless technology or concept that depends on the spatial characteristics of radio and microwave propagation.

In an indoor environment, channel variations which occur most frequently are due to the movement of personnel near the transmitting or receiving antennas and/or local movements of the terminals around a given location. Such spatial and short time variations in the indoor radio channel are studied and determined by performing wideband propagation experiments in line of sight and nonline of sight...

The resolution required for the spectrometer is at least 100 nm. The only BPM type proved to have a resolution better than 100 nm is a microwave cavity BPM [1]. The supression of the undesired symmetric cavity modes with coupling slots is also well established [2], [3]. This means a substantial improvement in the stability and the accuracy of the beam position measurement vs. a standard techniq...

Over-the-horizon radar (OTHR) and microwave radar networks can together generate track data over a wide surveillance region. However the data is often subject to ambiguity and uncertainty due to the complexities of the HF signal propagation environment, which give rise to multipath OTHR tracks, as well as ambiguities in target associations between multiple microwave radars. This report describe...

Several remedial measures like space diversity, frequency diversity, route diversity, increase in antenna height, antenna tilting, etc. have been tried by many workers to overcome the debilitating effect of multipath fading in fixed line-of-sight microwave and mobile communication links. Among these remedial measures, diversity techniques have been extensively studied in terms of improvement fa...

The defected ground structure (DGS) is one such technique which where intentionally modified to enhance the performance of the ground plane metal of a microstrip circuit. Importantly, in microwave application, the DGS plays an important role in analyzing the effect of surface and leaky waves. During the time of experimental analysis, the surface and leaky waves are affected by the propagation u...

A test of the s e d postdate of special relativity, the universality of the speed of light, w i n g the EXTRAS (Experiment on Timing Ranging and Atnwspheric Sounding) payload to be flown en board a Russian Meteor-SM satellite (launch date January 1997) is proposed. The propagation time of a light signal transmitted from one point to another without remction would be measured directly by compari...

This paper presents a tutorial overview of the use of coupling between nonadjacent resonators to produce transmission zeros at real frequencies in microwave filters. Multipath coupling diagrams are constructed and the relative phase shifts of multiple paths are observed to produce the known responses of the cascaded triplet and quadruplet sections. The same technique is also used to explore les...