Metamaterial antenna
Metamaterial antennas use engineered materials to improve miniaturized antenna performance.
Metamaterial antennas are a class of antennas that use metamaterials—materials engineered with novel, often microscopic, structures to produce unusual physical properties—to increase the performance of miniaturized (electrically small) antenna systems. Their purpose is to launch energy into free space, but they incorporate metamaterials to step up the antenna's radiated power. Conventional antennas that are very small compared to the wavelength reflect most of the signal back to the source, whereas a metamaterial antenna behaves as if it were much larger than its actual size because its novel structure stores and re-radiates energy.
- Radiated power efficiency
- up to 95 percent of an input radio signal
- Size relative to wavelength
- as small as one-fiftieth of a wavelength
- Example size at 300 mhz
- half a meter for a standard antenna; experimental metamaterial antennas are much smaller
- Earliest research configuration
- miniature dipole antenna surrounded with a double negative metamaterial (DNG) shell
- Commercial availability
- by 2009
Lore & Background
The earliest research in metamaterial antennas was an analytical study of a miniature dipole antenna surrounded with a metamaterial known as a negative index metamaterial (NIM) or double negative metamaterial (DNG). This configuration analytically and numerically appeared to produce an order of magnitude increase in power, while the reactance offered a corresponding decrease, and the DNG shell became a natural impedance matching network. Pendry et al. showed that a three-dimensional array of intersecting thin wires could create negative permittivity, and that a periodic array of copper split ring resonators could produce negative magnetic permeability. In May 2000, Smith et al. first successfully combined the split-ring resonator with thin wire conducting posts to produce a left-handed material with negative values of permittivity, permeability, and refractive index for frequencies in the gigahertz range. In 2002, a different class of negative refractive index metamaterials was introduced using periodic reactive loading of a 2-D transmission line, employing positive index material with negative index material, and was experimentally verified soon after.
Reader's Guide
Metamaterial antennas are significant because they overcome restrictive efficiency-bandwidth limitations for conventionally constructed miniature antennas. They permit smaller antenna elements that cover a wider frequency range, making better use of available space for space-constrained cases, such as large antenna arrays where miniature antennas with high gain are relevant. Metamaterials employed in ground planes offer improved isolation between radio frequency channels of MIMO antenna arrays, and high-impedance ground planes can improve radiation efficiency and axial ratio performance of low-profile antennas. They have also been used to increase beam scanning range by using both forward and backward waves in leaky wave antennas. The phase compensation provided by DNG materials, due to their negative index of refraction, can lead to miniaturized subwavelength cavity resonators and waveguides with applications below diffraction limits. Additionally, metamaterials can eliminate dispersion along microstrip transmission lines by correcting for the frequency dependence of effective permittivity, allowing for dispersion-compensating segments that simplify systems. These antennas aid applications such as portable interaction with satellites, wide angle beam steering, emergency communications devices, micro-sensors, portable ground-penetrating radars, wireless communication, space communications, GPS, satellites, space vehicle navigation, and airplanes.
Did You Know?
- Metamaterial antennas can radiate as much as 95 percent of an input radio signal.
- Experimental metamaterial antennas are as small as one-fiftieth of a wavelength.
- The earliest research involved a miniature dipole antenna surrounded with a double negative metamaterial (DNG) shell.
- Metamaterial antennas were commercially available by 2009.
Frequently Asked Questions
What is a Metamaterial antenna?
A Metamaterial antenna is an electrically small antenna that wraps its radiating element in engineered microscopic structures to make it behave as though it were far larger than its physical footprint. Its fundamental job is still to launch radio energy into free space, but the metamaterial layer dramatically increases how much of that energy actually gets radiated.
What are Metamaterial antenna's powers/role?
Where a conventional tiny antenna bounces most of its signal straight back to the transmitter, a Metamaterial antenna uses its novel material shell to push radiated-power efficiency up to roughly 95 percent of the input signal. In practical terms, it lets a very small device throw off nearly the same radio energy as a much larger conventional design.
How small can a Metamaterial antenna get?
Experimental Metamaterial antennas have been demonstrated at roughly one-fiftieth of the operating wavelength. At 300 MHz, where a standard antenna would need to be about half a meter long, a metamaterial version can be dramatically more compact.
What was the earliest Metamaterial antenna design?
The first research configuration paired a miniature dipole element with a surrounding shell of double-negative (DNG) metamaterial. That dipole-in-a-DNG-shell layout became the foundational proof-of-concept for the entire field.
When did Metamaterial antenna become commercially available?
By 2009, Metamaterial antenna technology had moved beyond the laboratory and reached commercial availability. That milestone marked the transition from purely experimental prototypes to products that could actually be purchased and deployed.
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