I think you can select the 3d object to be tilted/rotated. then click on the draw option on the panel, select rotate, a pop up box appears where you can input your preferred angle.

you can see the attached files, hope you find it useful!

in CST you can rotate your model by following path

Intially select your unit cell-> Modelling-> Transform -> Translate -> choose angle as you wish , example given in figure.

similarly please find these options in HFSS also. Thanks

Hi Hema

Rotate objects about the x-, y-, or z-axis using the Edit>Arrange>Rotate command.

To rotate objects about an axis:

1. Select the objects to rotate.

2. Click Edit>Arrange>Rotate.

The Rotate dialog box appears.

3. Select the axis about which to rotate the objects: X, Y, or Z.

4. Type the angle to rotate the objects in the Angle box.

A positive angle causes the object to be rotated in a counter-clockwise direction. A negative angle causes the object to be rotated in a clockwise direction.

5. Click OK.

The selected objects are rotated about the axis. To rotate and copy objects, use the Edit>Duplicate>Around Axis command.

But if you want to rotate your structure around any direction except for X, Y, and Z directions, you should create a new relative coordinate system with its origin at the point of your desired rotation and then rotate this:

Modeler > Coordinate System >Create > Relative CS

using rotate option we can do it. However one has to take care of axis of rotation.

Select the object and click on rotate present in tool bar, it will prompt for axis selection, X-Y-Z, then enter the angle in number (45 in your case) and see the result after clicking on OK. you can see the figure rotation by changing the axis check box in the 3d object window it self.