What are the top packages for software like this? What price range do they fall in?
I think this question could easily set off a heated discussion if this was on a dedicated RF design forum
Just like scopes and other tools there are quite a few choices. Usually there is a love/hate aspect somewhere for some vs others. 12 or so years ago I would have said Eagleware Genesys was the best (for me) for various reasons. But since Agilent/Keysight took over it went through a poor phase lasting several years. The recent versions are much improved. It's expensive these days and I've lost touch with prices. I think you could easily spend many, many thousands even for the basic version. Get lots of options and you are heading towards upmarket saloon car prices. The same applies to all of the tools from the other vendors below.
Genesys is still my favourite. It's like an old comfy pair of slippers for me because I've been using this SW right back to its roots nearly 30 years ago in the dark days of DOS
http://www.keysight.com/en/pc-1297125/genesys-rf-and-microwave-design-software?cc=USThe other popular one is
AWR Microwave Office and I've used this a lot too. Very powerful, very versatile, very expensive but not very intuitive to use (for some at least). At work I haven't upgraded to the latest version (for several versions now) because it does what I need already. The UI may have improved and I know some of my colleagues use the latest EM tools in the latest version with great success.
http://www.awrcorp.com/products/ni-awr-design-environment/microwave-officeThe link above seems to be their main page since NI took over. Looks a bit bland in terms of marketing... have I missed their proper/current website?
Sonnet EM is a brilliant EM Simulation tool for analysing PCB based filter designs, transmission lines and other structures on a PCB even with many layers. They do a free Lite version which is quite useful as they have upped the limits on the free version. However, if you don't do much RF design yet you probably won't like using Sonnet for a while. But it is my favourite EM simulation tool. It has helped me many times where other EM simulators have failed to model a problem. I've been using Sonnet for about 14 years at work.
http://www.sonnetsoftware.com/There are several other big ones like Keysight ADS and the range of ANSYS products. But we don't have these at work and I've never even tested a trial version. But they are very expensive and very powerful.
Keysight ADS is probably the daddy for most people...
http://www.keysight.com/en/pc-1297113/advanced-design-system-ads?cc=US&lc=engANSYS has a very powerful EM simulator amongst all its simulation tools. It has loads of other simulation packages too.
http://www.ansys.com/?gclid=Cj0KEQjwk-jGBRCbxoPLld_bp-IBEiQAgJaftY5zY9DlelESDo5pBF2lDyk1vsrRbw3pRazOTTHm_3UaAtwR8P8HAQOne thing I will warn everyone about is to not try any 'shortcuts' to getting any of these big name SW packages if you are running a business. At least one of the big names above will come after any company that does this. I won't name it for obvious reasons but I know of this stuff happening and they do try to detect (via the internet?) if you have ever run the SW on or offline.
You can get a free 30 day trial for many of the above and I think there are budget suites available too. But you need deep pockets even if running a business.
RFSIM99 is obviously very dated now and hasn't been revised for many years but it is free and quite a few people still use it
It might be good enough for your needs especially if used with Sonnet Lite. I don't know if Sonnet Lite can export s parameter data but if it can these two would be quite powerful when used together and they are both free? Note that RFSIM99 is just a linear simulator that operates in the frequency domain. It isn't like using SPICE. It's at its best if you want to look at transmission line models or filter models along with lumped components. You can't do any fancy transient analysis with it but it does come with some filter synthesis tools if you want to design lumped RF filters and simulate them.