We know that external excitation is directly provided to the active element of the arrangement i. The flow of current through the active element induces a voltage in the parasitic elements that cause current to flow through it. Whereas, the one shorter than the half-wave dipole i. So, the current flowing through it leads the voltage. As we know that director is placed in front of the driven elements, so, these directors add the field of the driven element in the direction away from it.
When multiple directors are placed in the arrangement then each director will provide excitation to the next one. Also, the reflector in the opposite direction as that of the director when accurately placed adds the field in the direction towards the driven element. This is done in order to reduce the losses due to the back radiated wave as much as possible.
In order to get the additional gain , multiple directors can be used in the direction of the beam. Basically, the induced voltage and the current flowing due to the induced voltage in the element varies with the spacing between the active and parasitic elements along with the reactance associated with the elements.
It is to be noted here that with the increase in distance between driven element and director, there will be more need for capacitive reactance in order to provide accurate phasing to the current in the director.
Thus, the length of the director is kept small to get the capacity reactance. Initially, excitation to the driven element is provided using feed lines. This causes the emission of radiation from reflector towards the director. Explore Audiobooks. Bestsellers Editors' Picks All audiobooks. Explore Magazines. Editors' Picks All magazines. Explore Podcasts All podcasts. Difficulty Beginner Intermediate Advanced. Explore Documents. Yagi-Uda Antenna Short Point. Uploaded by Lazy Guy.
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Flag for inappropriate content. Download now. Related titles. Carousel Previous Carousel Next. A Compact Dual-Polarized 8. Jump to Page. Search inside document. The result might be checked by direct measurement or by computer simulation. A well-known reference employed in the latter approach is a report published by the National Bureau of Standards NBS now the National Institute of Standards and Technology NIST that provides six basic designs derived from measurements conducted at MHz and procedures for adapting these designs to other frequencies.
The lower antenna is oriented report on the wave projector directional antenna. Yagi for vertical polarization, with a much lower resonant frequency. But using the above sort of analysis one Japan and it came to be associated with his name.
The mutual impedances plotted above directionality. Until the development of the log periodic antenna in the s it was the only type of antenna that could give adequate fringe reception in areas far from the television transmitter. Very complicated Yagi de- signs were developed to give adequate gain over the broad television bands. TV antennas are still a major applica- tion of the Yagi antenna.
Indeed, the lat- ter had so many antenna elements arranged on its back - in addition to its formidable turreted defensive armament in [1] Graf, Rudolf F. Modern Dictionary of Electronics 7 ed. ISBN Conjec- man airmen. Retrieved September 18, Modern Antenna Hand- formed from six discrete dipole elements, making it pos- book. John Wiley and Sons. Radar Basics. December This was the pref- ing motivated extensive development of the Yagi-Uda ace and notice in advance for a series of 11 papers with the antenna as a rooftop television reception antenna in the same title by Uda between on the antenna.
Retrieved September 11, Paper By H. Yagi by D. Pozar, in Proceedings History of Wireless. Uda; Y.
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