Rating system for antennas uses dBd, which means dB of improvement overĭBd, but given the way they exaggerate their claims, dBi is usually closer to The volume of the balloon remains constant. They distort the balloon considerably, but A-hah! Gain! That’s the way antennas work.Ĭomplicated antennas work by reducing radiation in most directions. Importantly, the balloon expanded in the other directions. To get more gain, an antenna must radiate in Has positive gain because it does not radiate equally in all directions. Will have the same gain when receiving as when transmitting, and also the same This sounds like a discussion of transmitting Is an antenna that radiates equally in all directions. “dBi” means “dB of improvement over an isotropic radiator”, which Radiation field: a torroid (doughnut shape). Solve an efficiency problem) and the loop (a variation on the folded dipole). But if you want, you can skip or skim the rest of this page withoutĬompromising your understanding of the pages that follow.ĭipole are the bowtie (which has wider bandwidth), the folded-dipole (which can Receive some channels well, but other channels poorly. Gain – a measure of how much signal the antenna will collect.īeam width – how directional an antenna is. Honest antenna makers have had to re-label their products likewise to avoid Unscrupulous people have labeled their antennas There is nothing different about an antenna for DTV or HDTV. Made for analog TV will work fine for DTV. Point on the surface is proportional to the gain in that direction. The length of a line from the origin to any Is the radiation diagram for a 9-element Yagi antenna that the author once usedĭiagram, imagine that the antenna is at the origin.
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