The problem of tracking radar targets in the low-angle region
Where conventional monopulse radars face difficulties
due to the presence of multipath waves is considered in this
thesis. The emphasis of the presentation is mainly directed
towards finding a new simple closed-form solution to the
coherent multipath problem over a smooth surface. Another
concern is to improve the performance of the
three-subapertures maximum-likelihood estimator when the two
received signals are in-phase or anti-phase at the centre of
The multipath phenomenon and its modelling for smooth
and rough surfaces are discussed and simulation results
obtained for different surfaces. subsequently the following
First. a new four-subapertures technique to improve the
in-phase and anti-phase performance of the maximum likelihood
estimator above is derived and simulation results are shown.
Then. an improved version of this technique is introduced as
a part of the new algorithm.
Second. a new three-subapertures trigonometric solution
to solve the coherent multipath problem is derived and
demonstrated by simulation results. This new method is
simpler than the maximum likelihood estimator above and very
similar in its estimation accuracy.
Third. the performance of the maximum entropy method is
tested for the coherent multipath problem by using the
three-subapertures arrangement of a linear array. Finally
the performances of the above three methods and the normal
phase monopulse radar are tested and compared to different surfaces
when the coherent and noncoherent multipath exist
together. Simulation results show that the performances of
the maximum entropy method and phase monopulse are much
better than the others when the target is low-tlyine over a
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.