AM Radios Research Articles

Significance of Medium-Wave AM Radio Broadcasting for Enhanced Disaster Resilience in Japan: A Case Study in the Kanto Region and Fukui Using Nonpowered Hoop-Shaped Radio

On the occasion of centenary anniversary of the Great Kanto Earthquake and commencement of radio broadcasting in Japan, this study reiterates the paramount importance of medium-wave (MW) AM broadcasting in safeguarding public safety and security. Utilizing the electromagnetic principles of MW, the author has earlier developed hoop-shaped radio (HOOPRA), which is a battery-free sustainable radio receiver. This study aims to determine the maximum achievable reception distance with HOOPRA for broadcasts from public stations, such as Nihon Hoso Kyokai (NHK) JOFG (927 kHz, 5 kW) in Fukui; and NHK JOAK (594 kHz, 300 kW) and JOAB (693 kHz, 500 kW) in the Kanto region. The significance of the findings in this study is that approximately 38 million individuals in the Kanto region, residing within an 80-km radius of JOAK or JOAB, can access broadcasts using only the energy of radio waves with HOOPRA. Additionally, ∼0.4 million people in Fukui, within a 15-km radius of JOFG, can potentially be recipients of the broadcast. Given that most transmitting stations operate at 5-kW power nationwide, HOOPRA can be effectively utilized within a 15-km radius of each station. Moreover, these outcomes validate the efficacy of HOOPRA as a radio receiver and provide valuable insights into the global potential applicability of MW AM radios. Furthermore, the current investigation underscores the need to reevaluate the significance of terrestrial MW broadcasting as a vital source of emergency information, especially in the event of anticipated natural disasters, such as the predicted Nankai Trough Earthquake.

Multichannel Adaptive Interference Cancellation for Full-Duplex High Power AM Radios

In space-limited co-located communication systems, wideband transmitters and receivers are deployed for various applications. The strong coupling between transmitters and receivers becomes a major concern. It is crucial to suppress the high power self-interference (SI) to prevent the receiver from working in the nonlinear area, or even saturating. As an effective approach to achieve this, the adaptive interference cancellation (AIC) technology is proposed in the context of a complex high power amplitude modulation radios. In this article, the system-level performance including the interference cancellation ratio requirements and the impact of the AIC on the receiving system is comprehensively studied for the first time. The operating mechanism of a single channel AIC system (AICS) and the configuration of a multichannel AICS are discussed. The performance analysis of the receiving system when implementing the AICS is performed, in terms of the noise figure and the sensitivity. By employing the proposed AICS, very limited effect is observed on the receivers, while the SI is successfully reduced with a high ICR, which fully satisfies the requirements for AM systems. The realization of the multichannel AICS as well as the measured cancellation performance are presented, verifying the proposed concept.

Business strategies for their websites of the most listened to radio stations in Buenos Aires

Este artículo propone un acercamiento explorativo por las estrategias de producción de contenidos y de comercialización de las radios de AM y FM más escuchadas de Buenos Aires, Argentina, para sus sitios webs. De esta manera, y como objetivo general del trabajo, se busca indagar y descubrir innovaciones o experiencias en la generación-producción de contenidos radiofónicos digitales así como en su comercialización o venta publicitaria.El estudio de los cambios que propone la convergencia tecnológica y mediática para las empresas de medios de comunicación implica la realización de distintos trabajos simultáneos. La observación y el análisis de los contenidos es sólo una parte que se complementa, en este trabajo, con la realización de entrevistas a productores, gerentes y directores de radios. En especial de sus secciones o departamentos digitales.De esta forma, uno de los principales hallazgos de este trabajo consiste en la falta de estrategias definidas, la ausencia de producciones radiofónicas específicas para la web y una búsqueda de mayor complementariedad con los contenidos tradicionales a través de textos y videos. En este marco, lo incierto del comportamiento del mercado publicitario tradicional atenta contra la toma de iniciativas por parte de las gerencias.

Trench Structure to Suppress Magnetic Field Leakage From an Aperture in a Metallic Enclosure

In hybrid vehicles, power converters such as inverters and dc–dc converters are installed in the power control unit (PCU). A strong current flows through the inductor of the output filter of the power converter, which causes electromagnetic interference in AM radios and other electrical equipment due to low-frequency noise. In this letter, we attempt to clarify the mechanism of low-frequency magnetic field leakage from the aperture of a simplified metallic enclosure representing a real PCU enclosure. A novel structure is herein proposed that suppresses leakage of the magnetic field by controlling the flow of eddy currents around the aperture. The proposed enclosure is manufactured, and its shielding factor is measured. The shielding factor of the proposed enclosure is confirmed to correspond approximately with that of an enclosure without an aperture.

Flexible Self-Aligned Amorphous InGaZnO Thin-Film Transistors With Submicrometer Channel Length and a Transit Frequency of 135 MHz

Flexible large area electronics promise to enable new devices such as rollable displays and electronic skins. Radio frequency (RF) applications demand circuits operating in the megahertz regime, which is hard to achieve for electronics fabricated on amorphous and temperature sensitive plastic substrates. Here, we present self-aligned amorphous indium-gallium-zinc oxide-based thin-film transistors (TFTs) fabricated on free-standing plastic foil using fabrication temperatures . Self-alignment by backside illumination between gate and source/drain electrodes was used to realize flexible transistors with a channel length of 0.5 μm and reduced parasitic capacities. The flexible TFTs exhibit a transit frequency of 135 MHz when operated at 2 V. The device performance is maintained when the TFTs are bent to a tensile radius of 3.5 mm, which makes this technology suitable for flexible RFID tags and AM radios.

Data Transmission on AM Broadcast with Acoustic OFDM

Data transmission via audio link on AM radio system is shown to be achievable by using Acoustic OFDM. We employ Acoustic OFDM to embed data onto audio contents that are then broadcast as AM radio signals. We tuned the parameters, and performed experiments. Text data as URL can be delivered to mobile phone through existing MF AM radio system and radios.

The therapeutic use of electromagnetic fields in plastic surgery

Before the 20th century, humankind was almost never exposed to sources of radio frequency (RF), electromagnetic fields (EMFs) other than those of the sun, or occasional blasts from other stellar sources. In this century, especially in recent years, there has been an explosion of uses of electromagnetic fields in the home, community, and workplace. Common sources of RF fields include computer monitors, AM radios, industrial induction heaters, RF heat sealers, medical diathermy, FM radios, mobile telephones, TV broadcasts, radar, and microwave ovens1 (see Table). An EMF can produce beneficial or adverse health effects, which may vary depending on the frequency spectrum of the source and its harmonics, the power of the devices, the duration of exposure, and the distance of the person from the source. View this table: Table Common sources of EMF and their frequency In the home, microwave ovens, mobile telephones, burglar alarms, TV sets, and hair dryers are a few of the devices that emit EMFs of up to 10 W/m2. In the community, the most common sources are commercial radio and TV broadcasting and telecommunication facilities, which in the average US urban center radiate a field of 50 W/m2. In the workplace, dielectric heaters used for wood lamination and the sealing of plastics, industrial electric heaters, and medical diathermy expose workers to greater than tens of W/m2. In medicine, the primary sources of exposure and overexposure exclusive of radiology are medical diathermy equipment to treat pain and inflammation and electrocautery devices. These medical devices are regulated in the United States and internationally.2–6 Claims that static magnets may …

Harold Alden Wheeler: a lifetime of applied electronics

The career of electronics engineer Harold Alden Wheeler, born in 1903 who contributed to the development of radio, television, and radar, is profiled. He experimented with radio in the days before broadcasting, and in 1922 he began a long-lasting association with the radio engineer Alan Hazeltine. In 1925 Wheeler made his most famous invention, a circuit that achieves automatic volume control (now called automatic gain control). It soon became, and remains today, a standard features of AM radios. In the 1920s and 1930s Wheeler made many other contributions, both practical and theoretical, to circuit design for radio receivers-AM, FM, and shortwave-and for television receivers. He excelled in the development of test equipment. During and after World War II, the design of antennas and of transmission lines become specialties of Wheeler's. His many honors include the Morris N. Liebmann Award, the Armstrong Medal of the Radio Club of America, and the IEEE Medal of Honor. >

"Monomax"-An Approach to the One-Chip TV

Monochrome TV receivers, like portable AM radios, have remained impenetrable to the skills of the linear IC designer - mainly because of very stringent cost requirements and relatively low demands on performance. There is, however, a market demand for a more sophisticated breed of receiver for portable use which is relatively complex when built with discrete components.

Highway advisory radio

In 1977, two years after its initial Notice of Proposed Rule Making in Docket 20509, the Federal Communications Commission (FCC) authorized the establishment of travelers' information stations (TIS) in the Local Government Radio Service, Part 90 of the FCC Rules and Regulations. Stations may he authorized on either 530 kHz or 1610 kHz for the purpose of providing useful noncommercial information to the traveling public by agencies of state and local governments via the AM radios with which most motor vehicles are currently equipped. Agencies of the federal government, such as the U.S. Park Service, have also been authorized by the Interagency Radio Advisory Committee (IRAC) to operate travelers information stations subject to the same rules adopted by the FCC. The background of highway advisory radio (HAR) and some of the considerations that led to the present rules are discussed. The effect on HAR system design of limitations imposed by the rules and by AM receiver characteristics is also discussed. Using field data acquired under a Federal Highway Administration (FHWA) contract, the problems of HAR antenna design within the FCC imposed limits are illustrated. Finally, the FCC "Part 15" alternative to the design of HAR systems is discussed. Conclusions are stated. The general conclusion drawn is that HAR can be, and has repeatedly proven to have been, a useful tool for traffic management and control.

A Wavepacket Generator for Demonstrating the Complementarity Rule

We describe an inexpensive demonstrator which produces electrical wavepackets of variable length. The packets contain from one to sixteen 1-MHz waves. Students may make a Fourier analysis of the packets with ordinary AM radios. They will discover dramatically different spectra, confirming the complementarity rule between packet length and bandwidth, ΔxΔk≳1.

Low Cost Voltage Regulator for Varactor Tuned Auto Radio

Electronic tuning for AM radios becomes possible with today's varactor diodes. The large capacitance values available permit smaller AM radios and remote tuning. Utilization of varactor diode tuning, however, demands extreme voltage stability, since small changes in the tuner reference voltage will change the diode capacitance and therefore the resonant frequency.