A stereo-synthetic aperture radar (stereo-SAR)-based technique is proposed to estimate the unknown terrain profile of a target area. This technique first mathematically builds up a virtual reference profile. An algorithm is afterward developed to estimate the relative height difference between the desired and reference profiles by using the trigonometric relationship between their relative SAR range distances, which allows for building up the height of the desired profile from the reference profile. This technique is advantageous and is simple in implementation because the virtual reference profile is constructed by using the same SAR range information as that used for the terrain profile under estimation, which is established by considering the measurement difference between two SAR receivers. It does not require the use of an existing known profile as the reference. Furthermore, we present a technique for calibrating the measured SAR range information, which significantly improves the estimation accuracy. Three practical examples are presented to demonstrate the feasibility of the developed technique.
A new scheme of a pulse-Doppler radar for the effective detection of metal objects in a short range of millimeter waves is presented. An omnidirectional transmitting antenna (TXA) is used to provide full angular coverage while a directional receiving antenna (RXA) collects the coded signals for the determination of range and angle of the arriving signal. A Doppler shift is created by making RXA horizontally rotate along the axis of TXA, which creates a relative velocity between the RXA and the target under detection. It is shown that the system may detect targets as small as 0.2 m2 with a high resolution.
As the applications of circular polarization (CP) antennas are widely used in the wireless communications, it is
significant to improve the CP antenna performance in aspect of axial ratio at the boresite direction. A good CP
performance is always desired. In this paper, we fabricate the amendatory one-dimensional photonic crystals for SHF
reflector antenna based on previous simulation results to compensate the circular-polarization discrimination as
encountered in many antenna's applications. The goal is to widen the beamwidth of radiation for crossed-dipole. The
performance is evaluated by measuring the 3dB axial ratio. Transfer matrix theory of multi-layer theory is used to solve
the field distribution cross layer. Although some tabulate plane-based (TPB) compensations can achieve a great
improvement for the crossed-dipole based reflector antenna, but it can only compensate the CP in a specified direction
and may distort in other directions. The one-dimensional approach can smooth the discrimination introduced by the
reflector and noise. The energy distribution of TE/TM polarizations are regulated with a one dimensional photonic
crystal to achieve a broader beamwidth, also the reflector antenna is fabricated and measured to validate the efficiency of
the proposed approach. The measured results show that the beamwidth is much wider than that before compensation.
The gain of 3D plot and the radiation patterns are also shown to verify if the side effect of compensation.