This would probably be suitable for your needs: https://www.amazon.com/Sangean-ANT-60-Short-Wave-Antenna/dp/B000023VW2
I use a Sangean ANT-60 as a travel antenna. It works well as a travel antenna or portable antenna for my Sangean ATS-909X. You can find several of these reel-up random wire antennas sold under different brand names. They are all similar antennas. They connect to the radio with a 3.5mm mono audio plug or clip onto the whip antenna. All will offer much better shortwave performance than with a telescopic whip, especially when used outdoors. All of these reel-up antennas are fairly short in length: about 23' (7m). This is to reduce front-end overloading when used with entry-level portables like the Tecsun PL-310ET.
Higher-end portables like the Sangean ATS-909X are designed to use wire antennas of any length without overloading. My main antenna at home is 270' (82m) of wire in a Skywire Loop configuration (horizontal loop).
A random wire or long wire antenna is a great choice for an outdoor shortwave antenna. So is a dipole.
A simple wire antenna can be any length of wire you want to try. Keep in mind that some receivers may overload if too much wire is used. I like PVC insulated stranded copper hook-up wire for my shortwave antennas. This wire is easily purchased in spools of different lengths on eBay or Amazon. Try 50' (15m) to begin with and longer after that. This is nice wire, easy to solder. Nearly invisible in the air for hiding an antenna in plain sight.
Remington black 18AWG stranded hookup wire 100'
A long wire antenna can work better than a random wire antenna. The rule of thumb for wire gauge: choose the lightest wire that will stay up without breaking. I use anywhere from 18 through 22AWG on my shortwave antennas. The bigger the AWG number (gauge) the smaller the wire. No balun, tuner or counterpoise is need to receive shortwave with a portable but these may be improvements like installing a grounding stake that you may try later on. Using coaxial cable between the antenna wire and the radio helps to reduce local RFI but is not essential. You will need to solder to build these antennas. Most portable shortwave radios with an antenna jack will require a 3.5mm (1/8") mono audio plug on the antenna. These plugs should be soldered to the wire unless you are using coaxial cable and BNC or other connectors and adapters.
-Random wire antenna: the wire antenna element is less than one wavelength long for the frequency in use.
-Long wire antenna: the wire antenna element is equal to or greater than one wavelength long for the frequency in use.
So, the same wire antenna may be a random wire or a long wire depending on the frequency in use.
My Sangean ATS-909X and Eton Grundig Edition Satellit are designed to handle wire antennas of any length without overloading. I have a couple of portable shortwave antennas. One is a simple 20' telescopic whip with a mag mount that grabs onto the steel trunk door on my car. The other is 300' (91m) of 18AWG wire on a spool. The near end of the wire has the 3.5mm plug. This portable shortwave DX antenna is as simple as it gets, just reel out the length of wire you can use and leave the rest on the spool. I have received good DX on both antennas but the long wire is the champ if room is available to put one up.
I haven't used this radio but it looks to be a good choice for your Dad. One of the better online reviewers at YouTube (Todderbert) liked the FM-AM version of this this radio from the same brand.
Greadio MD-T26 has fairly large digital display, simple controls and decent frequency coverage for shortwave broadcasts: 4.7 through 18 MHz. It does not feature SSB so it will not be great for utility listening or listening to hams but your Dad seems to be interested in shortwave broadcasts, anyway (so am I).
Buy one of these Sangean ANT-60 shortwave reel antennas too, and clip it to the whip antenna for better shortwave reception. If you can run the reel antenna outdoors, so much the better. Shortwave reception can be good in wooden-framed houses, not so good in other buildings. Shortwave suffers in dense urban area and apartments. Don't let the naysayers steer you wrong: there is still a lot of good shortwave broadcast listening out there especially with some practice and patience on the user's part. I listen to foreign shortwave broadcasts every day.
This radio is affordable. A top of the line portable like the Sangean ATS-909X2 will cost about US $225.
Added in edit: Portable shortwave radios usually work better on batteries than on the wall wart. Wall wart power supplies make noise that may be picked up on shortwave. No problem with this radio: it uses 4 D batteries which should last quite a while. Using AC power should be fine for FM and maybe the AM band. Just about all home electronics make noise that be heard on shortwave (including LED and fluorescent lighting). Turn 'em off for shortwave listening.
This should help you out. Be careful while hanging it - stay away from power lines.
EDIT USA (.com) link in place of Canada (.ca) link.