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On my dipoles and the one shango66 made in his excellent video on the subject there's no matching transformer and the dipole elements are connected directly to canter and shield (I opted to connect to a female connector so I can change the coax feed line length).
Note most dipole length formulas are written for 50ohm feedline since that is most common in Ham radio and communications applications. In his video shango66 shortens his antenna to match it to the 75ohm coax... you can tune any 50ohm dipole to 75ohm by reducing the length by a fairly constant percentage...if you look up his video and calculate what percentage of the length he trimmed you and apply that percentage to your antenna to match impedance.
Technically it is a good idea to have a 1:1 impedance ratio balun if you want to feed the dipole directly from the coax, but you can often get away without one like I and Shango66 have done. Your 300ohm to 75 ohm 4:1 matching transformer is technically a balun, but it is somewhat lossy by design and you'd have to track down a 300ohm dipole equation to make your dipole match.
Someone else will have to chime in on loops since I haven't built one for a remotely similar application.
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