Том 61, № 12 (2018)

The potential efficiency of optimal interperiod processing (IPP) of coherent batch radio pulses reflected from point air targets against the background of high-power clutter is analyzed during the radar operation in the pulse-Doppler mode with middle frequency of probing at ambiguous measurements of target range and velocity. This efficiency is compared with IPP efficiency during the radar operation in the coherent pulse mode. The analysis is performed at constant and variable probing intervals when the time span of the clutter source zone is both less and greater than the probing interval in pulse-Doppler radar, i.e. in the absence and presence of superposition of clutter from different range sections. The cases of complete match of parameters of clutter superposition are analyzed at different radial velocities of equipotent clutter layers, and also the cases of superposition of nonequipotent clutter layers, the powers of which are inversely proportional to the squared distance from their sources. In addition, the wobbling of intervals of signal probing is also taken into account.

A broadband patch antenna is presented with a modified rectangular patch containing three symmetrical slots and an asymmetrical slot. A U-slot is inserted into the ground plane, which enables a wide operational fractional bandwidth of 143% ranging 2.9–17.5 GHz. The modified rectangular patch offers acceptable omnidirectional radiation pattern at higher frequencies with radiation efficiency of 83 to 95%. The maximum achievable gain is 5.48 dBi across the entire bandwidth. The electromagnetic wave modeling is conducted using high frequency simulator structure (HFSS) and the circuit model is simulated with Advance Designing System (ADS) software. The housing effect is studied using vertical orientation of antenna to approximate its performance in the presence of conducting bodies. The proposed antenna architecture has small electrical dimension of 0.17×0.11λ. Simple configuration and wide bandwidth makes proposed patch antenna a suitable candidate for versatile communication applications.

This paper presents a wideband Sierpinski carpet fractal patterned rectangular Dielectric Resonator Antenna (DRA) operating in the X-band, which is characterized by dielectric waveguide model method (DWM). In order to decrease the cost of theDRAthe low-cost teflon is used as the material. Aprototype is realized to validate the results of the simulation. The paper provides a comparison between conventional rectangular DRA and fractal shaped rectangular DRAs of the first and the second iterations. The antenna design methodology is discussed along with its resonance and radiation characteristics. The validity of the obtained results is proved by the close match of the experimental and simulation results. The measurements on prototype show impedance bandwidth of 48% covering the entire X-band with similar radiation pattern throughout the band with a gain of 7.5 dBi over 9.0–11.5 GHz.