E-plane plate lens antenna of the target tracking radar for the US Air Force Nike Ajax anti-aircraft missile, 1954Dielectric lens/horn antenna in the Atacama Millimeter Array radio telescope
A lens antenna is a directional antenna that uses a shaped piece of microwave-transparent material to bend and focus microwaves by refraction, as an optical lens does for light.[1] Typically it consists of a small feed antenna such as a patch antenna or horn antenna which radiates radio waves, with a piece of dielectric or composite material in front which functions as a converging lens to collimate the radio waves into a beam.[2] Conversely, in a receiving antenna the lens focuses the incoming radio waves onto the feed antenna, which converts them to electric currents which are delivered to a radio receiver. They can also be fed by an array of feed antennas, called a focal plane array (FPA), to create more complicated radiation patterns.
To generate narrow beams, the lens must be much larger than the wavelength of the radio waves, so lens antennas are mainly used at the high frequency end of the radio spectrum, with microwaves and millimeter waves, whose small wavelengths allow the antenna to be a manageable size. The lens can be made of a dielectric material like plastic, or a composite structure of metal plates or waveguides.[3] Its principle of operation is the same as an optical lens: the microwaves have a different speed (phase velocity) within the lens material than in air, so that the varying lens thickness delays the microwaves passing through it by different amounts, changing the shape of the wavefront and the direction of the waves.[2] Lens antennas can be classified into two types: delay lens antennas in which the microwaves travel slower in the lens material than in air, and fast lens antennas in which the microwaves travel faster in the lens material. As with optical lenses, geometric optics are used to design lens antennas, and the different shapes of lenses used in ordinary optics have analogues in microwave lenses.
Lens antennas have similarities to parabolic antennas and are used in similar applications. In both, microwaves emitted by a small feed antenna are shaped by a large optical surface into the desired final beam shape.[4] They are used less than parabolic antennas due to chromatic aberration and absorption of microwave power by the lens material, their greater weight and bulk, and difficult fabrication and mounting.[3] They are used as collimating elements in high gain microwave systems, such as satellite antennas, radio telescopes, and millimeter wave radar and are mounted in the apertures of horn antennas to increase gain.
^Graf, Rudolf F. (1999). Modern Dictionary of Electronics, 7th Ed. Elsevier. p. 420. ISBN 9780080511986.
^ abKumar, Sanjay; Shukla, Saurabh (2015). Wave Propagation and Antenna Engineering. PHI Learning Pvt. Ltd. pp. 357–359. ISBN 9788120351042.
^ abJohnson, Richard C. (1993). Antenna Engineering Handbook, 3rd Ed(PDF). McGraw-Hill. pp. 16.2–16.3. ISBN 007032381X.
^Silver, Ed., Samuel (1984). Microwave Antenna Theory and Design. Institution of Electrical Engineers. p. 388. ISBN 9780863410178.
A lensantenna is a directional antenna that uses a shaped piece of microwave-transparent material to bend and focus microwaves by refraction, as an optical...
as antennas at UHF and microwave frequencies, above 300 MHz. A lensantenna uses a lens to direct or collect microwave radiation. An array antenna is...
microwaves. Linear slot antennas emit narrow fan-shaped beams. Used as UHF broadcast antennas and marine radar antennas. Lens A lensantenna is made from a layer...
often use dielectric lenses, commonly called a lensantenna to refract electromagnetic radiation into a collector antenna. Lenses can become scratched...
of reflector and lensantennas. Unlike traditional reflector and lensantennas, however, the focusing effect in a Fresnel zone antenna is achieved by controlling...
("dish") antennas are the most widely used directive antennas at microwave frequencies, but horn antennas, slot antennas and lensantennas are also used...
Monopulse radar systems can be constructed with reflector antennas, lensantennas or array antennas. Historically, monopulse systems have been classified...
plane arrays to be used with the extended hemispherical lens. Luneburg lens Fresnel lensLensantenna Frid, Henrik (2016). "Closed-Form Relation Between the...
layers of lens material. The electronics lie outside of both the pupil and the iris so there is no damage to the eye. There is a wireless antenna inside...
A transmitarray antenna (or just transmitarray or called as layered lensantenna) is a phase-shifting surface (PSS), a structure capable of focusing electromagnetic...
computer-generated display superimposed on the world outside. An antenna on the lens could pick up a radio frequency. In 2016, work on Interscatter from...
to the development of metamaterial antennas and metamaterial microwave lenses for miniature wireless system antennas which are more efficient than their...
(2021). "A Sensing Demonstration of a Sub THz Radio Link Incorporating a LensAntenna". Progress in Electromagnetics Research Letters. 99: 119–126. doi:10...
the impedance of free space (see horn antenna for more details). When used with a offset, parabolic or lensantenna, the phase center of the horn is placed...
In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio...
An antenna array (or array antenna) is a set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves...
by a flat lens versus being dispersed. The earliest research in metamaterial antennas was an analytical study of a miniature dipole antenna surrounded...
Audio's Digital Directivity Control Technology Design of Cost-Effective Beam Steered Phased Array Antenna with Enhanced Gain using Metamaterial Lens v t e...
control, radomes, high-frequency battlefield communication and lenses for high-gain antennas, improving ultrasonic sensors, and even shielding structures...
a transmitter, which is connected to an antenna which radiates the waves. They are received by another antenna connected to a radio receiver, which processes...
known for his work in radar and antenna design. Among his inventions were the Rotman lens, the sandwich wire antenna, and the trough waveguide. Walter...
hardware is shown toward the end of the film, he is mostly depicted as a camera lens containing a red and yellow dot, with such units located throughout the ship...
Fresnel lens Fresnel number Fresnel zone antenna Photon sieve G. W. Webb, I. V. Minin and O. V. Minin, “Variable Reference Phase in Diffractive Antennas”, IEEE...
aperture of an optical system (including a system consisted of a single lens) is a hole or an opening that primarily limits light propagated through the...
Global Information
