Is Yaggi Udda Antenna simulation is possible on ADS MOMENTUM 2008?

Probably not. Momentum is a planar simulator.

Microwave123

The planar MoM simulators assume a substrate material that extends to infinity. This is a problem for antennas that fire to the side (horizon).

In your case the substrate is "air", so it should work. However, some other NEC based codes where antenna segments are modelled as wires might be more efficient.

It is possible if you want to simulate a planar, pcb-printed yagi antenna.

Of course, it is also possible if you want a normal yagi "in air". Just define air (erel=1) as you substrate and use absorbing boundary condition above and below.

Designing the feed for yaggi uda on PCB is very difficult task. Methods of Moments (ADS Momentum) is used for 2D structures for 3D it is better to use HFSS.

Very few people use HFSS for yagi antennas. The usual method is to use NEC-based MoM codes, which are much more efficient for this application.

dear volker, I see what you mean but wouldn't ads assume an infinitely thin copper? which might cause problems for pattern calculation in the end-fire configuration?

No. You can define metal thickness and set solver model to thick metal.