Infinite wavelength resonant antennas

[Stanley514]

Could somebody explain what does mean "infinite wavelength antenna" and what advantages does it have? What is resonant antenna and advantages?
http://webcache.googleusercontent.com/search?q=cache:fHdO6P-aoIIJ:dspace.nitrkl.ac.in:8080/dspace/bitstream/2080/1320/1/MMET.pdf+&cd=4&hl=en&ct=clnk&gl=ca

 

[sophiecentaur]

Sorry but your link doesn't work. Stanley.
Many (if not most) antennae operate at a frequency at which the reactive part of their impedance is a lot lower than the resistive part. This happens when the Inductive impedance is nearly equal and opposite to the Capacitative impedance and that is at a resonance. The antenna can then be 'matched' to the transmitter and feeder cable and the efficiency can be optimised.
Don't take this as all you need to know about antennae. They are fiendishly hard devices to understand - but it's a start.

 

[Baluncore]

A tuned antenna is designed as a “resonant circuit”. It operates best at one frequency. Tuning tends to reject off frequency signals while favouring the wanted signal frequency.

There are many different broadband antennas that cover a significant bandwidth, often a factor of ten. Some examples are the cone, discone and loop or patch antennas that are smaller than about 1/10 wavelength. These are used where a wide band of operation is required.

The directional characteristic of small elements is a simple dipole. By using an array of several small wideband elements and inserting a controlled time delay or phase shift in their feed lines, the directional characteristics of the array can be controlled. That is called “beam forming” or “aperture synthesis”.