Very High-Power Long-Wave Broadcasting Station

Smith, Carl E.; Hall, J. R.

doi:10.1109/jrproc.1954.274789

Cited by 20 publications

(2 citation statements)

References 5 publications

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“…Of course this action increases the guy radius or the needed real estate with an increase in the lot cost. Sometime the guy lower ends are placed over small towers in order to increase this angle and making the loading more effective [4]. Technical information on this matter is very scarce after Smith & Johnson paper.…”

Section: Umbrella Top Loadingmentioning

confidence: 99%

Short medium frequency AM antennas

Trainotti

2001

IEEE Trans. on Broadcast.

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Lately short antennas have again attracted broadcaster attention. These kinds of antennas have been used since the 1920s. At that time it was the logical antenna as a new application of this service after more than twenty years of telegraphic transmissions. Telegraphic transmissions were the most important radio communication service at that time, and because of the long range needed the lowest frequencies as possible were employed. For this reason very short antennas were used even if their size was enormous. Top loaded monopoles were very popular and this technique was employed for broadcast use before the vertical transmitting mast exhaustive study was carried on in the thirties. Nowadays a short antenna would be useful for low power applications and specially to be mounted on building tops. Of course this kind of antennas is not intended to replace the optimum monopoles or vertical dipole where maximum efficiency, maximum gain and antifading properties were achieved after exhaustive studies and after long experience theoretically and practically achieved. CFAs, short monopoles, short dipoles and short folded monopoles have been analyzed from the theoretical and practical point of view in order to choose the simplest and most efficient model to fulfill downtown stringent requirements.

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Section: Umbrella Top Loadingmentioning

confidence: 99%

Short medium frequency AM antennas

Trainotti

2001

IEEE Trans. on Broadcast.

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“…In the years that followed, Doherty amplifiers continued to be used in a number of medium and high power low-frequency (LF) and medium-frequency (MF) vacuum tube AM transmitters [4,5]. continues to rise linearly, with its current rising twice as fast as the current in the carrier tube in order to reach its PEP value at maximum output power.…”

Section: List Of Tablesmentioning

confidence: 99%

A 3.6 GHz Doherty Power Amplifier with a 40 dBm Saturated Output Power using GaN on SiC HEMT Devices

Baker¹

2000

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This manuscript describes the design, development, and implementation of a linear high efficiency power amplifier. The symmetrical Doherty power amplifier utilizes TriQuint's 2 nd Generation Gallium Nitride (GaN) on Silicon Carbide (SiC) High Electron Mobility Transistor (HEMT) devices (T1G6001032-SM) for a specified design frequency of 3.6 GHz and saturated output power of 40 dBm. Advanced Design Systems (ADS) simulation software, in conjunction with Modelithic's active and passive device models, were used during the design process and will be evaluated against the final measured results. The use of these device models demonstrate a successful first-pass design, putting less dependence on classical load pull analysis, thereby decreasing the design-cycle time.The Doherty power amplifier is a load modulated amplifier containing two individual amplifiers and a combiner network which provides an impedance inversion on the path between the two amplifiers. The carrier amplifier is biased for Class-AB operation and works as a conventional linear amplifier. The second amplifier is biased for Class-C operation, and acts as the peaking amplifier that turns on after a certain instantaneous power has been reached. When this power transition is met the carrier amplifier's drain voltage is already approaching saturation. If the input power is further increased, the peaking amplifier modulates the load seen by the carrier amplifier, such that the output power can increase while maintaining a constant drain voltage on the carrier amplifier.ii The Doherty power amplifier can improve the efficiency of a power amplifier when the input power is backed-off, making this architecture particularly attractive for high peak-to-average ratio (PAR) environments. The design presented in this manuscript is tuned to achieve maximum linearity at the compromise of the 6dB back-off efficiency in order to maintain a carrier-tointermodulation ratio greater than 30 dB under a two-tone intermodulation distortion test with 5 MHz tone spacing. Other key figures of merit (FOM) used to evaluate the performance of this design include the power added efficiency (PAE), transducer power gain, scattering parameters, and stability. The final design is tested with a 20 MHz LTE waveform without digital pre-distortion (DPD)to evaluate its linearity reported by its adjacent channel leakage ratio (ACLR).The dielectric substrate selected for this design is 15 mil Taconic RF35A2and was selected based on its low losses and performance at microwave frequencies. The dielectric substrate and printed circuit board (PCB) design were also modeled using ADS simulation software, to accurately predict the performance of the Doherty power amplifier. The PCB layout was designed so that it can be mounted to an existing 4" x 4" aluminum heat sink to dissipate the heat generated by the transistors while the part is being driven. The performance of the 3.6 GHz symmetrical Doherty power amplifier was measured in the lab and reported a maximum PAE of 55.1%, and a PAE of 48.5...

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Spulen, Übertrager und magnetische Werkstoffe

Zinke

Seither²

1982

Widerstände, Kondensatoren, Spulen Und Ihre Werkstoffe

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Very High-Power Long-Wave Broadcasting Station

Cited by 20 publications

References 5 publications

Short medium frequency AM antennas

Short medium frequency AM antennas

A 3.6 GHz Doherty Power Amplifier with a 40 dBm Saturated Output Power using GaN on SiC HEMT Devices

Spulen, Übertrager und magnetische Werkstoffe

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