Saddle Antenna
CHAPTER -2 SADDLE ANTENNA
2.1 NOVEL UWB ANTENNA DESIGN CONCEPT
Saddle antenna is a unique kind of flared antenna. This Ultra Wide Band antenna is based on using of two smoothly shaped flares of a simple geometrical structure – the saddle. The first flare, larger in size, serves as an antenna base, reflector and one of the radiator arms. The second flare, smaller in size, operates as the other arm of the radiator. An apparent idea is exploited in this design that an “ideal” UWB antenna would operate as a broadband well-matched transformer for the current at its driving ports to the radiated fields that leave the antenna aperture. Besides terminal matching, the antenna would provide a necessary spatial distribution of the radiated energy. The antenna is studied through numerical full-wave simulations with several prototypes in terms of alignment and excitation. The achieved directivity in the band is uniform, greater than 5 dB with considerably low VSWR, involves constant beam width and suitability for pulse transmission with minimized distortions.
Unlike traditional narrowband systems, their UWB counterparts operate by employing very short electrical pulses of nanosecond and sub nanosecond duration resulting in very wide transmission bandwidths ranging from several hundred megahertz up to several gigahertz. Such huge bandwidths must be supported with suitable UWB antennas that behave unavoidably as band pass filters. UWB antenna designer may chose among known antenna solutions or create new ones to meet diverse system-related requirements, electrical, mechanical, manufacturing and cost constraints. Some authors considered historically an ideal UWB antenna that radiates time derivatives of the input signal but this principle is not helpful to design practical UWB radiators. Rather other rational and physics-based guidelines could be more productive. [4]
Reviewing the UWB antenna related literature [4-7] leads to a
2.1 NOVEL UWB ANTENNA DESIGN CONCEPT
Saddle antenna is a unique kind of flared antenna. This Ultra Wide Band antenna is based on using of two smoothly shaped flares of a simple geometrical structure – the saddle. The first flare, larger in size, serves as an antenna base, reflector and one of the radiator arms. The second flare, smaller in size, operates as the other arm of the radiator. An apparent idea is exploited in this design that an “ideal” UWB antenna would operate as a broadband well-matched transformer for the current at its driving ports to the radiated fields that leave the antenna aperture. Besides terminal matching, the antenna would provide a necessary spatial distribution of the radiated energy. The antenna is studied through numerical full-wave simulations with several prototypes in terms of alignment and excitation. The achieved directivity in the band is uniform, greater than 5 dB with considerably low VSWR, involves constant beam width and suitability for pulse transmission with minimized distortions.
Unlike traditional narrowband systems, their UWB counterparts operate by employing very short electrical pulses of nanosecond and sub nanosecond duration resulting in very wide transmission bandwidths ranging from several hundred megahertz up to several gigahertz. Such huge bandwidths must be supported with suitable UWB antennas that behave unavoidably as band pass filters. UWB antenna designer may chose among known antenna solutions or create new ones to meet diverse system-related requirements, electrical, mechanical, manufacturing and cost constraints. Some authors considered historically an ideal UWB antenna that radiates time derivatives of the input signal but this principle is not helpful to design practical UWB radiators. Rather other rational and physics-based guidelines could be more productive. [4]
Reviewing the UWB antenna related literature [4-7] leads to a