I came across plans for a homebrew antenna at
Signal strength...100%, bit-error rate...0%:-
The only part I had to buy was the 300Ω <-> 75Ω balun (part number FD78K from Maplin, about €3.50)
I have been running with this for over a year now and it works perfectly. I have made a few more of them for family and friends with equal success, even in locations where analogue RTE service was poor.
If you really really can't pick up the Saorview terrestrial service, there is also the Saorsat satellite service. You will need a Ka-band LNB (which is different to the normal type of LNB you would use for picking up Sky/Freesat etc. from Astra 2) and a dish aligned on 9oE. I tried it with an ordinary cheap-and-cheerful satellite receiver and a dinky 40cm dish mounted in a bicycle-repair stand...
...and it works a treat. You don't get TV3 or 3e at the moment but hopefully that will change. I haven't tried it, but I understand that it is possible to use a slightly bigger dish and mount a normal LNB off-centre and you can pick up both Saorsat and Sky/Freesat etc. using a single dish. www.tvtrade.ie (where I bought the Ka-band LNB among other goodies) sell a mounting bracket sized for exactly this purpose (the positioning of the LNB is critical for this trick to work). Its a great site with a great range of well-priced products. They also make their own excellent tutorial videos. Highly recommended.