Currently, there are no additional arguments for uniform circular arrays ('phased.UCA') that allows you to set the starting location.
The workaround is to instead use a conformal array ('phased.ConformalArray') as it is more general than the uniform circular array. To see an example of how to convert a conformal array into a uniform circular array, execute the following command in the MATLAB R2020a command window:
>> web(fullfile(docroot, 'phased/ug/conformal-array.html'))
To control the position of the elements, use the Azimuth angle (defined by 'ang' in the example). This array has angles (range: -180 to 180 deg), and the order of the angle determines the location of the elements. Therefore, instead of starting this array of Azimuth angles at -180 deg (9 o'clock position), you can start it at 180 deg (3 o'clock position). However, it is important to wrap the angles so that they stay in the range of -180 to 180 deg. This is included in the example on the line immediately following the definition of the 'ang' variable.
For further information regarding the current release, please follow the link below:
