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A method for determining the phase center location of ultra-wideband monopole antennas is presented and used to investigate its movement within the frequency band of the antenna. It is then used to study the effects of different band-stop designs on the degree of the phase center movements. It is shown that some designs can adversely affect the phase of the radiated field, by displaying larger phase...
The double-ridged horn is widely used in frequency-domain measurements and can exhibit a nearly 20:1 impedance bandwidth, albeit with substantial and undesirable pattern variations as well as anomalies related to input impedance match and power transfer. The horn is frequently employed in EMC measurements and it is also being adapted as a UWB and time-domain, short-pulse test antenna. In this chapter...
Antennas for radiating high-power mesoband (medium-bandwidth) electromagnetic signals are critical to the mission of upsetting electronics at a distance. When operated at frequencies of a few hundred megahertz, RF weapons require highly efficient antennas that can fit into a small volume. Most of the existing antennas, such as pyramidal horns, are too large to fit onto certain platforms of interest...
A few years after the early investigation on ultra-wideband (UWB) wireless system, considerable research efforts have been put into the design of UWB antennas and systems for communications. These UWB antennas are essential for providing wireless wideband communications over very short distances at very low power densities. This chapter presents numerical analysis of a small slotted UWB antenna by...
A method to widen the microwave spectrum by radiating two pulses of different FWHM is presented. Based on this method, a high-power ultra-wideband dual-pulse radiating antenna is developed. The antenna is made up of a half-impulse radiating antenna (IRA) over a ground plane. The diameter of the reflector is 3 m with focal length 1.2 m and the ground plane is a rectangle of metal with length of 4 m...
A novel printed antenna with a trimmed notch cut, fed by a simple microstrip line, is proposed and described. It is designed and fabricated for ultra-wideband (UWB) wireless communications under the band (3.1–10.6 GHz). This antenna is composed of a planar rectangular patch with notch cut and a transition step fed by a microstrip line with a partial ground plane. A parametric study is carried out...
For angular scanning a true-time array is developed for UHF ultra-wideband (UWB) applications in time and/or frequency domain. It is based on a 4 × 4 array with antipodal exponentially tapered slot antennas (ETSA, Vivaldi) and a 3-bit phase shifter. Distances of antenna elements are designed to be compromise between gain, scanning angle, side/grating lobe levels. The uniform spaced and fed array maximizes...
Differential antennas are becoming of great interest for UWB systems because of the simplicity to connect them to an input amplifier. In this chapter a planar elliptical differential (PED) UWB antenna fed by coplanar striplines is investigated. This allows the antenna to be in the same plane as the circuit board, reducing the size of the system, and facilitating the connection to the input amplifier...
This chapter presents the results of investigations of a 64-element array developed for radiation of directed ultra-wideband wave beams with multimegavolt effective potential. The array is excited from a 1-ns length bipolar pulse generator with the output impedance of 12.5 Ω. The total output impedance of a feeder system used for pulse distribution by the array elements is 0.78 Ω. The array aperture...
This chapter presents results of the investigations directed to creation of large ultra-wideband active receiving array antennas with dual polarization. The array element is made on the basis of two crossed electric dipoles. Each arm of the dipoles is loaded to the single-stage FET amplifier. Four such elements form a 2 × 2 module being a component of a multielement array antenna.
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