Hoping to Make a Star Base Useful

Try mixing different PD guns, as they all have different ranges they will fire at different times as the fighters come in, that might help.

You could also give the base a Sat bay, and launch a load of PD sats before the combat even starts (they will launch far too slowly in combat to be of much use, unless you have lots of bays, which would be better used for fighters or drones).

Use Point-Defense Blasters. They require both Energy Pulse and PD research, and basically are the only PD that doesn't suck. Couple of PDBs will chew up just about anything. They're the only PD weapon that can expect to match incoming threats on a 1:1 or better basis. Everything else tends to be a 3:1 or worse, meaning you'll need 3 of them to counter one threat.

Agreed - point-defence blasters, preferably on many satellites surrounding the base is the best option I can think of. If they fix the "units automatically launched as fast as possible in combat" bug (I want to manually launch in locations of my choosing, not dribble units all over the place) that can't be switched off, I'd even load my bigger warships with PD satellites (and perhaps seeker satellites - big warships should be focussing on Mounted weapons!).

The autolauch is not a bug: In Strategies, Turn the switch 'Launch All Units During Combat' to False to disable it...

...and yes try mixing PDs -> you have 5 Pds to play with
In BM mod i mix regular, blaster and flak PDs for optimal defence (on bases, sats and WPlats) and it works very well.
But if you play stock game--> "Couple of PDBs will chew up just about anything" (stock is so imba imho :/)

You can use this with direct fire weapons on your SBase (try to have dif range or rofire for each weapon)
PDSats works even better but it needs some micro...
Btw ablative armor could help vs fighters...
Good luck

"Can you expect the unexpected? No, you cannot. You can only expect to be surprised."

Hmm... ok so the "units launched on a 2nd launch command into the same group don't get their supplies" bug still exists. Which simply means I have to tell everything to launch at the same time, but I can choose when to give that command. A... vast improvement, yes... still waiting for the day when that supplies bug gets fixed (simplest solution being to make a new group of units for each separate launch command).

Right, time to research Satellites while my empire's in a lull between wars.

for a static defense I like to just drop about 50 or so PDB sats then manually line em up in rows of about 25 (50-100 total generally depending on importance of what I'md defending) tends to let different targets come into range and be blasted before they get in range of other sats and so those can fire a bit later and so on and by the time the last fire the first can fire again and it works very well in killing more enemies that way. (you get a lot less overlap)

Of course I allow max (20,000?) ships and units so I rarely have to worry about not being able to place so many in defense

BTW putting about 10 sat launchers on a base and around 100 sats inside is very effective as well against fighters... that "shell" effect works nicely (autolaunch) You'll lose a lot of cheapo sats but the main base should survive and the enemy will lose all it's fighters. Sadly no sat can possibly be armored/shielded against a heavy fighter... Heavy fighters can simply hold far too much firepower. (12+ guns at 600 damage per gun is insane lol)

Put some bomblet launcher point defences on the base as these will generally engage at the same time as the satellite based shorter ranged weapons supplementing the weight of fire and cutting down on the satellite losses a bit at the cost of a few points of ordinance

In my games where i tested in varied tech levels, i found out PD , bomblets and flak do a terrible job fending off fighters. The problem with bomb and flaks is that they concentrate on a single unit and the area effect just doesnt seem to work that well. PD just arent powerful enought to blow the fighters, and tech increasing, favours the fighters more than PD.
So, in my games, i designed bases with unmounted anti-proton beans, as you wont need a whole lot of damage to deal with a single fighter. So i just pump as much APB as i can coupled with a few PD to deal with missiles. PD's IMO just work against missiles.
I tested my design against 45+ fighters and was able to survive. The same ting with a dread, a single dread beat around 30 or so fights with just APB. But these will suck against regular ships.