Microwave Communications--An Historical Perspective

Sobol, H.

doi:10.1109/tmtt.1984.1132829

Cited by 20 publications

(7 citation statements)

References 15 publications

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“…This inverse seventh-order proportionality differs significantly from the inverse cubic behavior of the electromagnetic Chu limit. Preliminary results in in [18] did not provide the equation for Q given above in (2). Since the luminosity in (2) and orbital energy in (13) account for all radiation losses, Q would include both gravitational quadrupole radiation polarizations, plus "+" and cross "×.…”

Section: Theorymentioning

confidence: 99%

“…Einstein's 1916 general relativity field equations predicted the gravitational waves first observed in 2015, much as Maxwell's electromagnetic theory in the 1860's predicted the radio waves first observed by Hertz in 1880's and later applied by Marconi in the 1890's [1][2][3][4]. Even before Einstein's general relativity theory, similarities between electrostatics and Newtonian gravity lead Heaviside to propose a gravitational analog to electromagnetics [5].…”

Section: Introductionmentioning

confidence: 99%

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Theoretical and observed quality factor of gravitational quadrupoles

Weldon

2018

Phys. Rev. D

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Useful insights into the complicated physics of gravitational waves can often be drawn from approximations to analogous physics of electromagnetic waves. Here, we present a gravitational form of the electromagnetic Chu limit that sets bounds on the achievable Q (quality factor) relating the ratio of stored energy to radiated energy in the underlying fields. In particular, we answer two fundamental physics questions: 1) what is the theoretical Q for gravitational quadrupole radiation sources, and 2) can gravitational Q be observed from recent measured astronomical data? Gravitational Q is shown to follow an inverse seventh-order power law, and gravitational-wave data is used to find observed values of Q for GW170817. Inasmuch as electromagnetic Q serves a central role in design and analysis of electrically-small antennas, the proposed gravitationalQ offers the potential for a similar utility in the design and analysis of gravitationally-small detectors and quadrupoles.

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Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical and observed quality factor of gravitational quadrupoles

Weldon

2018

Phys. Rev. D

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“…However, once Alexander Graham Bell patented the telephone and started providing voice telephony, it challenged the dominance of the telegraph system. The advancement in cable/ optical fiber and switching and routing mechanisms (see Beaufils 2000;Cioffi 2011;Martinelli 2012) as well as the advent of wireless systems, such as microwave radio links, satellite communications, and cellular technologies (see Sobol 1984;Zeng et al 1999;Lawton 2005;Evans et al 2011), stimulated higher transmission capacity, efficiency, reach, and mobility. The commercialization of the Internet allowed vendors to offer various products and services (see Press 1994;Leiner et al 1997).…”

Section: Literature Reviewmentioning

confidence: 99%

Broadband and narrowband Internet in Nepal

Parajuli

Haynes

2017

Asia-Pac J Reg Sci

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This paper examines the relationship between asymmetric digital subscriber line (broadband) and dial-up (narrowband) Internet subscribers in Nepal. While the number of broadband subscribers is increasing, the number of narrowband subscribers has been decreasing over the last couple of years. As expected, broadband subscribers ''Granger cause'' narrowband subscribers to decline. This suggests that digital subscriber lines are a superior good that is a substitute and replace dial-up services. This relationship should be stable in the short-run. The public sector incumbent Nepal Telecom provides both digital subscriber lines and dial-up access while commercial Internet Service Providers supply dial-up services. Hence, a large proportion of the revenue of the commercial providers is likely to be eroded compared to the incumbent. Given this context and to ensure that there is free and fair competition to support rapid growth in the Internet sector, the Government of Nepal needs to address important regulatory and policy issues related to this narrowband-broadband transition.Keywords Narrowband Á Broadband Á Internet Á Dial-up Á Asymmetric digital subscriber line Á Nepal JEL Classification L86 Á L96 Á O18 Á C32

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“…However, the understanding of the practical aspects of propagation and antenna design were still in their infancy. Approximately 15 years after Professor Hertz's experiments, the first long range transatlantic transmissions were achieved by Guglielmo Marconi using low frequency grounded wireless waves [3]. He also produced the first truly microwave transmitter placing a half-wavelength dipole at the focal point of a cylindrical parabolic reflector both spatially filtering the antenna beam pattern and bandpass filtering the spark gap generated source.…”

Section: Introductionmentioning

confidence: 99%

“…With the discovery of the magnetron and klystron tubes capable of kW power amplification, many wireless systems were migrating to higher frequencies [3]. By this time, the benefits of operating in the various bands of the microwave frequency range were well known in terms of desirable propagation characteristics and reduced wireless system size.…”

Section: Introductionmentioning

confidence: 99%