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Ricardo Álvarez - IEEE Xplore Author Profile
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Ricardo Álvarez

Also published under: Ricardo Alvarez, R. Alvarez, R. Álvarez

Publications
7
Citations
98
Publications by Year
20172022
Co-Authors:
Show All Co-Authors (15)
Image of author Ricardo Álvarez

Ricardo Álvarez

Also published under: Ricardo Alvarez, R. Alvarez, R. Álvarez

Affiliation

Department of Electrical Engineering
Universidad Técnica Federico Santa María
Santiago, Chile

Publication Topics

Biography

Ricardo Alvarez (Member, IEEE) was born in El Salvador, Chile. He received the degree in electrical engineering from the University of Chile, Santiago, Chile, in 2005, and the Ph.D. degree in electrical engineering from the RWTH Aachen University, Aachen, Germany, in 2016. He is currently Professor with the Universidad Técnica Federico Santa María and a Researcher with the Solar Energy Research Center, Chile. His main interests are power system planning, operation, and optimization, large-scale integration of renewable energies, and the use of artificial intelligence in power system applications.(Based on document published on 22 February 2021).
Publications
7
Citations
98
Publications by Year
20172022
Co-Authors:
Show All Co-Authors (15)
Author's Published Works

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Converting a small standard receiver into a hand-held narrow-aperture HF direction finder

O.G. Villard;G.H. Hagn;J.M. Lomasney

IEEE Antennas and Propagation Magazine
Year: 1994 | Volume: 36, Issue: 5 | Magazine Article |
Cited by: Papers (2)
Describes a compact HF-antenna accessory, designed for use with book-sized portable receivers. It converts the receiver for sky-wave-direction finding (DF), co-channel-interference reduction, and radio-frequency-interference (RFI) location, while being hand-carried by the user. When the system is operated in the DF mode while in motion, site-related errors in line of bearing (LOB) can be reduced b...Show More

Converting a small standard receiver into a hand-held narrow-aperture HF direction finder

O.G. Villard;G.H. Hagn;J.M. Lomasney

Year: 1994 | Volume: 36, Issue: 5 | Magazine Article |

The modeling and measurement of HF antenna skywave radiation patterns in irregular terrain

J.K. Breakall;J.S. Young;G.H. Hagn;R.W. Adler;D.L. Faust;D.H. Werner

IEEE Transactions on Antennas and Propagation
Year: 1994 | Volume: 42, Issue: 7 | Journal Article |
Cited by: Papers (8)
The method of moments (MoM) was used in conjunction with the geometric theory of diffraction (GTD) for predicting the elevation-plane radiation patterns of simple high-frequency (HF) vertical monopoles and horizontal dipoles situated in irregular terrain. The three-dimensional terrain was approximated by seven connected flat plates that were very wide relative to the largest wavelength of interest...Show More

The modeling and measurement of HF antenna skywave radiation patterns in irregular terrain

J.K. Breakall;J.S. Young;G.H. Hagn;R.W. Adler;D.L. Faust;D.H. Werner

Year: 1994 | Volume: 42, Issue: 7 | Journal Article |

Cascaded-loop MW/SW receiving antenna rejects sky-wave interference and enables diversity reception at SW

O.G. Villard;G.H. Hagn;J.M. Lomasney

IEEE Transactions on Broadcasting
Year: 1992 | Volume: 38, Issue: 4 | Journal Article |
Cited by: Papers (2)
It is shown that cascaded loop antenna (CLA) technology can be used to improve the quality of reception of HF broadcasts in two ways. The first is interference reduction by means of the stable null response, which is equally effective with either sky wave or ground waves. This requires one receiver and one CLA. Addition of a second CLA and receiver makes possible reception with binaural diversity....Show More

Cascaded-loop MW/SW receiving antenna rejects sky-wave interference and enables diversity reception at SW

O.G. Villard;G.H. Hagn;J.M. Lomasney

Year: 1992 | Volume: 38, Issue: 4 | Journal Article |

Backyard Range-the story of compact, directional low-impedance loop antennas (LILAs) for short-wave broadcast reception

G. Hagn;C.A. Hagn

IEEE Antennas and Propagation Magazine
Year: 1992 | Volume: 34, Issue: 3 | Magazine Article |
Cited by: Papers (1) | Patents (2)
The development of a horizontal version of the tuned, wide-strip low-impedance loop antenna (LILA) for use as a short-wave broadcast receiving antenna is recounted. The horizontal loop antenna (HLA) received the horizontal electric field component of the down-coming sky wave (actually, the projection of the vertical magnetic field component) relatively unattenuated, for elevation angles of arrival...Show More

Backyard Range-the story of compact, directional low-impedance loop antennas (LILAs) for short-wave broadcast reception

G. Hagn;C.A. Hagn

Year: 1992 | Volume: 34, Issue: 3 | Magazine Article |

Methodology and computer tools to semi-automate assessments of shortwave broadcast coverage resulting from multiple transmissions

G.H. Hagn;M. Lee;D.R.L. Worthington;L.O. Harnish

IEEE Transactions on Broadcasting
Year: 1988 | Volume: 34, Issue: 2 | Journal Article |
Cited by: Papers (3)
A computer-assisted methodology, developed for using a point-to-point ionospheric propagation and communications system performance model to assess shortwave broadcast coverage, is presented. The listening area is approximated by a set of geographic coordinates (test points), and the required power gain (RPRG) for the link from each transmitter site to each test point is computed using the IONCAP ...Show More

Methodology and computer tools to semi-automate assessments of shortwave broadcast coverage resulting from multiple transmissions

G.H. Hagn;M. Lee;D.R.L. Worthington;L.O. Harnish

Year: 1988 | Volume: 34, Issue: 2 | Journal Article |

HE receiving antenna directivity patterns and gain for ionospheric propagation model predictions for shortwave broadcasting

G.H. Hagn

IEEE Transactions on Broadcasting
Year: 1988 | Volume: 34, Issue: 2 | Journal Article |
Cited by: Papers (3)
Elevation-plane relative directivity patterns of a 9-ft rod measured with the XELEDOP full-scale HF antenna pattern measurement system are compared with values assumed by the Voice of America (VOA) and the British Broadcasting Corporation (BBC). Values of such directivity patterns and gain for a 7.5-ft monopole with sixteen buried ground radials, measured at the same site, are compared with predic...Show More

HE receiving antenna directivity patterns and gain for ionospheric propagation model predictions for shortwave broadcasting

G.H. Hagn

Year: 1988 | Volume: 34, Issue: 2 | Journal Article |

RELEDOP: a full-scale antenna pattern measurement system for high-powered HF transmitting antennas

R.H. Stehle;G.A. DesBrisay;A.L. Whitson;G.H. Hagn

IEEE Transactions on Broadcasting
Year: 1988 | Volume: 34, Issue: 2 | Journal Article |
Cited by: Papers (5) | Patents (3)
A system is presented that utilizes a towed, 3-axis receiver called RELEDOP. RELEDOP is a receiving elementary dipole with optional polarization that measures the transmit directivity patterns of over-the-horizon backscatter (OTH-B) radars and shortwave broadcast transmitting arrays. A dielectric tow cable and a fiber-optic link to the towing aircraft permit excellent electromagnetic isolation of ...Show More

RELEDOP: a full-scale antenna pattern measurement system for high-powered HF transmitting antennas

R.H. Stehle;G.A. DesBrisay;A.L. Whitson;G.H. Hagn

Year: 1988 | Volume: 34, Issue: 2 | Journal Article |

A methodology for modeling the reliability, availability and maintainability (RAM) of a generic shortwave broadcast relay station

J.H. Willett;D.L. Harvey;G.H. Hagn

IEEE Transactions on Broadcasting
Year: 1988 | Volume: 34, Issue: 2 | Journal Article |
Cited by: Papers (1)
A methodology for developing a reliability, availability and maintainability (RAM) model that is applicable to evaluating conceptual designs for shortwave broadcast relay stations is described. A generic relay station (GRS) that has nine major subsystems exclusive of ionospheric propagation path is proposed. The reliability of the propagation path to the listeners is not addressed. An example of t...Show More

A methodology for modeling the reliability, availability and maintainability (RAM) of a generic shortwave broadcast relay station

J.H. Willett;D.L. Harvey;G.H. Hagn

Year: 1988 | Volume: 34, Issue: 2 | Journal Article |

Shortwave broadcasting band spectrum occupancy and signal levels in the continental United States and Western Europe

G.H. Hagn;R.H. Stehle;L.O. Harnish

IEEE Transactions on Broadcasting
Year: 1988 | Volume: 34, Issue: 2 | Journal Article |
Cited by: Papers (16)
The initial results are described for monitoring using a mobile spectrum monitoring unit (MSMU) that has the capability of fast sampling of radio signals in the frequency spectrum between 2 MHz and 1 GHz. In the summer and autumn of 1987, the MSMU was used to measure signal level and spectrum occupancy in the shortwave band (2-30 MHz) at four locations in the continental United States (CONUS) (i.e...Show More

Shortwave broadcasting band spectrum occupancy and signal levels in the continental United States and Western Europe

G.H. Hagn;R.H. Stehle;L.O. Harnish

Year: 1988 | Volume: 34, Issue: 2 | Journal Article |

Comparison of IONCAP Predictions with AN/TRQ-35(V) Oblique-Incidence Sounder Measurements for a One-Month Conus Test During July and August 1982

Lawrence O. Harnish;George H. Hagn;William T. Alvarez

MILCOM 1983 - IEEE Military Communications Conference
Year: 1983 | Conference Paper |
Cited by: Papers (1)
The US Army Special Forces conducted a one-month test of high frequency (HF) propagation predictability during July and August 1982. One site was located at Ft. Bragg, NC, and it received transmissions from sounders located at Ft. Knox, KY (696 km), Ft. Leavenworth, KS (1439 km), and Ft. Lewis, WA (3830 km). AN/TRQ-35(V) oblique-incidence ionospheric sounders were used on each of the test paths at...Show More

Comparison of IONCAP Predictions with AN/TRQ-35(V) Oblique-Incidence Sounder Measurements for a One-Month Conus Test During July and August 1982

Lawrence O. Harnish;George H. Hagn;William T. Alvarez

Year: 1983 | Conference Paper |

VHF Radio System Performance Model for Predicting Communications Operational Ranges in Irregular Terrain

G. Hagn

IEEE Transactions on Communications
Year: 1980 | Volume: 28, Issue: 9 | Journal Article |
Cited by: Papers (3)
This paper describes a VHF communication system performance model which can predict the probability of successful communications (ps) in irregular terrain for both analog and digital systems. The Longley-Rice model is used to predict the propagation effects. A new noise model, based upon information in CCIR Report 258, is used to help estimate predetection signal-to-noise ratios (R). A communicati...Show More

VHF Radio System Performance Model for Predicting Communications Operational Ranges in Irregular Terrain

G. Hagn

Year: 1980 | Volume: 28, Issue: 9 | Journal Article |

Radio system performance model for predicting communications operational ranges in irregular terrain

G.H. Hagn

29th IEEE Vehicular Technology Conference
Year: 1979 | Conference Paper |
Cited by: Papers (3)
SRI International (formerly Stanford Research Institute) has developed a VHF communication system performance model which predicts the probability of successful communications (Ps) in irregular terrain for both analog voice and digital systems. The Longley-Rice model is used to predict the propagation effects. A new noise model, based upon information in CCIR Report 258, is used to help estimate p...Show More

Radio system performance model for predicting communications operational ranges in irregular terrain

G.H. Hagn

Year: 1979 | Conference Paper |

On the Definition and Estimation of Spectrum Occupancy

A. D. Spaulding;George H. Hagn

IEEE Transactions on Electromagnetic Compatibility
Year: 1977 | Volume: EMC-19, Issue: 3 | Journal Article |
Spectrum occupancy for channels and bands of similar channels is defmed. A distinction is made between transmission occupancy and message occupancy. The measurement time required to determine if a given channel is occupied is considered as well as the time required to estimate the degree of transmission occupancy with a given statistical confidence. Nonparametric (distribution-free) statistical te...Show More

On the Definition and Estimation of Spectrum Occupancy

A. D. Spaulding;George H. Hagn

Year: 1977 | Volume: EMC-19, Issue: 3 | Journal Article |

Land-Mobile Radio Communication Channel Occupancy, Waiting Time, and Spectrum Saturation

George H. Hagn;Thomas I. Dayharsh

IEEE Transactions on Electromagnetic Compatibility
Year: 1977 | Volume: EMC-19, Issue: 3 | Journal Article |
Cited by: Papers (5)
The operational utility of a shared land-mobile radio communication channel to any given user depends upon his waiting time to access the channel and the quality of the channel once it is available. This paper describes a method of obtaining waiting time estimates from measurements of channel occupancy made with a scanning receiver and discusses land mobile spectrum saturation in the context of wa...Show More

Land-Mobile Radio Communication Channel Occupancy, Waiting Time, and Spectrum Saturation

George H. Hagn;Thomas I. Dayharsh

Year: 1977 | Volume: EMC-19, Issue: 3 | Journal Article |

Definition of a Measurement Capability for Spectrum Managers

George H. Hagn;Donald M. Jansky;Thomas I. Dayharsh

IEEE Transactions on Electromagnetic Compatibility
Year: 1977 | Volume: EMC-19, Issue: 3 | Journal Article |
Cited by: Papers (6)
This paper defimes a spectrum measurement capability that will be directly useful to the managers of the radio-frequency spectrum. The proposed uses of such a capability are categorized as measurements to 1) determine spectrum occupancy, 2) check for and document compliance with assignment rules, regulations, and standards, and 3) facilitate electromagnetic compatibility (EMC) among the various sy...Show More

Definition of a Measurement Capability for Spectrum Managers

George H. Hagn;Donald M. Jansky;Thomas I. Dayharsh

Year: 1977 | Volume: EMC-19, Issue: 3 | Journal Article |

Problems in Obtaining a System Electromagnetic Compatibility (EMC) Figure of Merit (FOM)

George H. Hagn

1974 IEEE Electromagnetic Compatibility Symposium Record
Year: 1974 | Conference Paper |
A direct approach and a building-block approach for developing a system electromagnetic compatibility (EMC) figure of merit (FOM) are discussed. Each approach is based upon the channel denial concept, and a co-site environment is assumed. The direct approach requires the use of a computer program whereas the building-block approach permits the use of rather simple scoring formulas for selected EMC...Show More

Problems in Obtaining a System Electromagnetic Compatibility (EMC) Figure of Merit (FOM)

George H. Hagn

Year: 1974 | Conference Paper |

Comments on the performance of selected low-power HF radio sets in the tropics

G.H. Hagn;W.R. Vincent

IEEE Transactions on Vehicular Technology
Year: 1974 | Volume: 23, Issue: 2 | Journal Article |
Cited by: Papers (5)
The performance of five low-power HF radio sets was measured at 3.6 MHz under field conditions in Thailand. Variations in performance were noted for CW and voice transmissions as a function of type of set, type of antenna, time of day, and communication range (5-100 mi) in tropical forest (jungle), mountain, and delta terrain. Radio teletype (RTTY) tests over longer paths (out to 1320 km) were mad...Show More

Comments on the performance of selected low-power HF radio sets in the tropics

G.H. Hagn;W.R. Vincent

Year: 1974 | Volume: 23, Issue: 2 | Journal Article |

On the relative response and absolute gain toward the zenith of HF field-expedient antennas--Measured with an ionospheric sounder

G. Hagn

IEEE Transactions on Antennas and Propagation
Year: 1973 | Volume: 21, Issue: 4 | Journal Article |
Cited by: Papers (8)
A technique for using a pulse-type ionospheric sounder to measure the relative response of HF antennas toward the zenith is described, and some ionospheric limitations on the technique are discussed. Example measurements are given for selected field-expedient antennas (e.g., dipoles, slant wires, and whips) in forested and cleared areas, and the short-path skywave gain over an isotropic radiator i...Show More

On the relative response and absolute gain toward the zenith of HF field-expedient antennas--Measured with an ionospheric sounder

G. Hagn

Year: 1973 | Volume: 21, Issue: 4 | Journal Article |

Measured relative responses toward the zenith of short-whip antennas on vehicles at high frequency

G.H. Hagn;J.E. van der Laan

IEEE Transactions on Vehicular Technology
Year: 1970 | Volume: 19, Issue: 3 | Journal Article |
Cited by: Papers (10)
The response toward the zenith of an untuned 16.5- foot vertical whip antenna mounted on the rear comer of a jeep, relative to the response of a half-wave horizontal dipole at 15 feet above ground, was measured at high frequency with an ionospheric sounder. At 4 MHz, the relative response of the whip was -52.5 dB, and it increased with frequency at a rate greater than 12 decibels per octave (i.e.,...Show More

Measured relative responses toward the zenith of short-whip antennas on vehicles at high frequency

G.H. Hagn;J.E. van der Laan

Year: 1970 | Volume: 19, Issue: 3 | Journal Article |

Comments on the performance of VHF vehicular radio sets in tropical forests

W.R. Vincent;G.H. Hagn

IEEE Transactions on Vehicular Technology
Year: 1969 | Volume: 18, Issue: 2 | Journal Article |
Cited by: Papers (11)
Some of the effects of tropical forests (jungle) on the performance of VHF radios have been explored. To better understand average propagation effects, the dielectric constant and the conductivity of selected forests have been measured. The effect of forests on the gain and pattern of simple VHF antennas has been explored, as well as signal loss along a trail. Scattering of VHF radio waves by near...Show More

Comments on the performance of VHF vehicular radio sets in tropical forests

W.R. Vincent;G.H. Hagn

Year: 1969 | Volume: 18, Issue: 2 | Journal Article |

Pit Sheelding for Communication Sateluite Ground-Terminal Antennas

George H. Hagn;Michael G. Keenen;Harry A. Turner

IEEE Transactions on Electromagnetic Compatibility
Year: 1965 | Volume: 7, Issue: 2 | Journal Article |
Cited by: Papers (3)
Several authors have suggested that hills, earth walls, excavated pits, or same other such obstacle might be used to shield ground-terminal antennas of satellite-to-ground communication links from radiated interference propagating at low angles (troposcatter, groundwave, etc.). As the tradeoff is between access or look angle and shielding efficiency, such pits would be most useful for synchronous ...Show More

Pit Sheelding for Communication Sateluite Ground-Terminal Antennas

George H. Hagn;Michael G. Keenen;Harry A. Turner

Year: 1965 | Volume: 7, Issue: 2 | Journal Article |

Measurement of Radiation from Selected TD-2 Microwave Relay Stations

Harry A. Turner;George H. Hagn

IEEE Transactions on Electromagnetic Compatibility
Year: 1965 | Volume: 7, Issue: 2 | Journal Article |
The optimum frequency band for satellite communication systems is generally agreed to be between 1 and 10 Gc. Frequencies in this band are, however, already allocated and or assigned. One solution to this spectrum occupancy problem is frequency sharing, and one of the systems in this band with which a satellite system might have to coexist is the TD-2 microwave radio relay sstem (3.7-4.2 Gc). This...Show More

Measurement of Radiation from Selected TD-2 Microwave Relay Stations

Harry A. Turner;George H. Hagn

Year: 1965 | Volume: 7, Issue: 2 | Journal Article |

Measurement of Radiation from Selected TD-2 Microwave Relay Stations

George H. Hagn;Harry A. Turner

1964 6th National Symposium Electromagnetic Compatibility
Year: 1964 | Conference Paper |
The optimum frequency band for satellite communication systems is generally· agreed to be between 1 and 10 Gc. Frequencies in this band are, however, already allocated. One solution to this spectrum occupancy problem is frequency sharing, and one of the systems in this band with which a satellite system might have to coexist is the TD-2 microwave radio relay system (3.7-4. 2 Gc). This paper presen...Show More

Measurement of Radiation from Selected TD-2 Microwave Relay Stations

George H. Hagn;Harry A. Turner

Year: 1964 | Conference Paper |

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