Short backfire antenna
A short backfire antenna (or short back-fire, SBA, SBF or SBFA) is a type of a directional antenna, characterized by high gain, relatively small size, and narrow band.
It has a shape of a disc with a straight edge, with a vertical pillar with a dipole acting as the driven element in roughly the middle and a conductive disc at the top acting as a sub-reflector. The bottom disc has the diameter of two wavelengths, and its collar (edge) is quarter the wavelength tall. The center pillar consists of two coaxial tubes (their diameter has to be carefully chosen to give the desired impedance), with a quarter-wavelength slot cut into the outer tube[1].
This structure behaves like a resonant cavity, resulting in a substantial gain in small space.
Short backfire antennas are used in some satellites, and in high-frequency (short-wavelength) communication equipment (often for communication with satellites) on ships and other applications where rugged construction is an advantage. They are also used for wireless LANs. The SBF antenna was invented by Dr. Hermann W. Ehrenspeck[2] of Air Force Cambridge Research Labs based at Hanscom Air Force Base in Bedford, MA and was used for, among other purposes, to provide Tactical Satellite Communications for U.S. Army ground forces due to the SBF's portability and gain.
The bandwidth of the antenna can be increased by using a conical main reflector instead of a flat one.
Archery target antenna is an evolution of the short-backfire antenna. The name is derived from its appearance. Its base diameter is 5 wavelengths (5 λ), the rim height is 0.7 λ, the diameter of the small center reflector is 0.7 λ, its height above the base is 0.7 λ as well, the height of the dipole above the base is 0.35 λ, there is one more reflector - an annular reflector - at the same height as the center reflector, with inner diameter 2.2 λ and outer diameter 3.7 λ. [1]
Short backfire antennas are able to achieve high aperture efficiencies, at right cavity size even beyond 100%.[3]
See also
- FRARS: 2.4 GHz short backfire antenna
- v
- t
- e
- Isotropic radiator
- Batwing antenna
- Biconical antenna
- Cage aerial
- Coaxial antenna
- Crossed field antenna
- Dielectric resonator antenna
- Dipole antenna
- Discone antenna
- Folded unipole antenna
- Franklin antenna
- Ground-plane antenna
- G5RV antenna
- Halo antenna
- Helical antenna
- Inverted-F antenna
- Inverted vee antenna
- J-pole antenna
- Mast radiator
- Monopole antenna
- Random wire antenna
- Rubber ducky antenna
- Sloper antenna
- Turnstile antenna
- T2FD antenna
- T-antenna
- Umbrella antenna
- Whip antenna
- Adcock antenna
- AS-2259 Antenna
- AWX antenna
- Beverage antenna
- Cantenna
- Cassegrain antenna
- Choke ring antenna
- Collinear antenna array
- Conformal antenna
- Corner reflector antenna
- Curtain array
- Folded inverted conformal antenna
- Fractal antenna
- Gizmotchy
- Helical antenna
- Horn antenna
- Log-periodic antenna
- Loop antenna
- Microstrip antenna
- Moxon antenna
- Offset dish antenna
- Patch antenna
- Phased array
- Planar array
- Parabolic antenna
- Plasma antenna
- Quad antenna
- Reflective array antenna
- Regenerative loop antenna
- Rhombic antenna
- Sector antenna
- Short backfire antenna
- Slot antenna
- Sterba antenna
- Vivaldi antenna
- WokFi
- Yagi–Uda antenna
References
- ^ Ehrenspeck, Hermann W. (1965). The Short-backfire Antenna. Air Force Cambridge Research Laboratories, Office of Aerospace Research, United States Air Force.
- ^ RongLin Li; Thompson, D.; Tentzeris, M.M.; Laskar, J.; Papapolymerou, J. (February 2005). "Development of a wide-band short backfire antenna excited by an unbalance-fed H-shaped slot". IEEE Transactions on Antennas and Propagation. 53 (2): 662–671. doi:10.1109/TAP.2004.841291. ISSN 0018-926X.
- ^ "Weatherproof UHF & microwave cavity antennas (S53MV)". Retrieved 18 October 2012.