One of the main activities of Applied Electromagnetics is the design and modelling of antennas, particularly for use in wide band applications. This work is based around the use of the computational electromagnetics codes but also uses analytics methods where appropriate. The results have been verified in many cases with experimental measurements.
Because of the generality of the computational electromagnetics codes it is possible to model a wide variety of antenna types. Dipoles, bow-ties, horns, and reflectors have been analysed as well is arrays of simple elements like dipoles. Analysis allows measurements of the radiation pattern as well the impedance and other characteristics of the antenna.
A good example of the sort of work that can be carried out on antennas is given by a development that was done recently for application to ground penetrating radar (GPR). An existing antenna, a "kipper" horn, was being used for GPR applications but was found to be too large. An analysis of the horn showed the critical elements that were required for the performance and these were used to design a new horn incorporating several features that allowed the performance to be retained whilst reducing the size by the required amount.
The new design is known as a CODA (COmpact Directive Antenna).
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The illustration shows the horn in a transmit/receive pair arrangement separated by a ground plane. |
| The graph is a comparison of the forward transfer functions for the original kipper horn, the new CODA horn design as modelled using GAEL, and the measured performance of an actual realisation of the horn. Experimental data is courtesy of DERA Malvern. |
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The movie shows the CODA horn in action as a pulse propagates out into space. |