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Jan 5, 2014 · Or, what will happen when the antenna dimension is limitlessly reduced? One answer was given by J. D. Kraus, who showed that a small antenna could have effective aperture of as high as 98 percent of that of a half-wave dipole antenna, if the antenna could be perfectly matched to the load [1].
- Kyohei Fujimoto, Hisashi Morishita
- 2014
When that device has a small size or limited space for a classic reso-nant antenna, various techniques are used to implement reduced-size antennas.
There is a fundamental theoretical limit to the bandwidth and radiation efficiency of electrically small antennas. Attempting to circumvent these theoretical limits can divert resources in an unproductive manner to tackle a problem which is insurmountable.
- 772KB
- 14
As a practical matter, the maximum directive gain (directivity) of an antenna depends upon its physical size compared to wavelength. The uniformly illuminated aperture type of antenna has been found to give a higher gain in practice than other antennas, at least for large apertures.
- 8MB
- 12
Feb 27, 2021 · Basically, because a sinewave can be broken in half in the time axis, you get a full internal coherent reflection with the forward applied voltage when you match the antenna length to the electrical half \$\lambda\$ of the applied voltage.
Sep 19, 2011 · Based on this observation of the incorrect energy velocity, a time-domain approach is used to derive the fundamental limit on radiation- Q against electrical size of an antenna. A new form of...
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Jun 1, 2015 · All theories have reached the same conclusion that the size of an antenna can only be reduced at the expense of its bandwidth and gain [1, 2]. These theories provided a lower limit on the antenna Q -factor given its dimensions.
