Although numerous antenna applications demand broad
bandwidths, many antenna configurations simply cannot achieve the bandwidths
these applications require. For example, both communication and radar systems
operate over broad bands of frequency (greater than 2:1 and typically 10:1), yet
the electrically or physically limited (compact) antennas available for these
applications (e.g. low-profile antennas mounted above conducting metallic
platforms as on tanks, aircraft, etc.) often cannot facilitate these needs.
Indeed, many existing compact antennas operate as resonant circuits that provide
bandwidths of 1.1:1 (10%) or less and therefore require active tuning or
multiple resonant antennas to achieve the necessary ranges. When existing
broadband antennas (e.g. spiral antennas, log-periodic dipole arrays) are used
in these applications they suffer efficiency losses both due to close proximity
to conducting materials or as a result of near field power losses effectuated by
the absorbing materials required in the antennas? construction.
Researchers at Arizona State University have developed
low-profile antennas that have an essentially semi-infinite bandwidth of
operation. These Momentum Antennas operate as waveguiding structures with
matched radiating discontinuities rather than as resonant circuits and require
no tuning. Because the antennas incorporate no absorbing materials the
efficiency of the Momentum Antennas is merely a function of the area the
antennas occupy on the platform. One design of momentum antennas is particularly
suited for broadband applications that simultaneously demand electrically small
antennas. The antennas may conform to the surface of their mounting platforms
(e.g. civilian vehicles, military vehicles, cell phone frame, etc.) and may
operate to both transmit and receive electromagnetic waves.
Potential Applications
- Wireless Communications (e.g. radio, television,
point-to-point, LAN, etc.)
- Radar Systems
Benefits and Advantages
- Provides Semi-Infinite Operational Antenna Bandwith ?
Momentum Antennas do not operate as resonant circuits; therefore, the antennas
have no reactance and demonstrate a feed having purely resistive load of the
order of the radiation resistance; obeys the Fano-Chu efficiency limit
corollary for low-frequencies
- Conforms to Its Metallic or Conductive Platform ?
delivers low-profile, non-encumbering antennas
- Requires No Absorbing Materials in Construction ?
obviates need for tuning
- Offers Efficiency as a Function of the Surface Area the
Antenna Occupies