You know the answer. It’s the antenna you’ve got up.
If you can erect a tower and put a three-element tri-bander up with a rotor you’re going to have a wonderful experience. Europe will be an everyday experience. The Middle East will be assessable as will Scandinavia and all of Russia. South America will be very loud and more often than not you’ll work scores of Japanese stations.
The world, my friend, will be your oyster.
BUT if I could have only one antenna it would be a multi-band vertical! Yes verticals are noisy compared to dipoles but their angle of radiation is substantially lower and thus allows for really long DX contacts.
My general rule of thumb is if i can hear it on the vertical I can work it. I used a ground-mounted hand-made custom vertical which looks a lot like a Butternut HF6V (80-10). Under the antenna I have 60 ground radials and the antenna is fed with low loss coax.
There are days when the vertical outperforms my HyGain Explorer with 40-meter extensions. The other weekend I could clearly hear VKs and ZLs. I use the vertical with 5 watts SSB to work the Caribbean when the beam is pointed north and I don’t have time to rotate it.
Next up I’d add an 80/40 dipole or if space was limited a G5RV-JR dipole which at 50 feet can fit in just about anywhere.
A combination of a vertical and dipole is ideal for new contesters although one or the other on their own will do.
If I was getting serious but didn’t want to invest in a tower I’d consider putting up a smaller Hex beam on a temporary support and putting it up and bringing it down for each contest.
Yes that’s a pain but the advantages of running a beam can not be over stated.
If you’ve got the room, a full size wire antenna such as a Carolina windom or full-size mono-bander will work wonders with an auto tuner.
Your internal auto tuner might work on 40-10 but it will struggle on 80 and likely give up on 160. This is why some guys buy old-fashioned manual tuners that can be way bigger than the actual radio.
Used manual contest-quality tuners from companies such as Drake, Viking and Dentron work really well. LDG auto tuners work pretty well as do manual Ten Tec tuners. You’ll likely want an external SWR/Watt Meter Bridge.
As for coax dump the RG-58 and replace it with RG-8X or better still RG-213 or ever better LMR-400. If you’re going to bury the cables you’re going to want direct bury cable or you’ll need to bury a conduit that drains out rain and ground water.
Having said that I’ve used ordinary LMR-400 for 8 years now with no appreciable effect but I will be replacing the cable every 10 years no matter what as degradation in the cable is extremely hard to notice.
Finally avoid all trick, cute and expensive antennas. All antennas are based on the simple dipole (two poles) feed in the centre. Anything else is window dressing.
It can be very good window dressing when it comes to beams which are essentially one dipole feed with reflecting and directing elements added.
It can be very bad window dressing especially when it comes with it’s own custom bag or extravagant claims of gain.
Anything that’s shortened is compromised. Three element beams have traps and loading coils and they’re a compromise but the addition of extra elements changes the outcome. Verticals which aren’t full size are compromised. Dipoles that aren’t full-size single band are compromised.
So since we live in a world of compromise (In other words I’m not single living on 50 acres on top of the escarpment and free from conservation oversight) we have to make choices.
When it comes to antennas here’s where it’s at for me.
I’ve got a HyGain Explorer beam at 16.6 meters covering 40-10. It works very well.
I’ve got the HF-6V vertical. It works pretty good.
I’ve got an Alpha-Delta slightly shortened 80/40 dipole at 30 feet. It’s way too low to be good but it works sort of.
I’ve got a G5RV-JR (40-10) especially for the WARC bands and I like it.
For 160 I’ve got an Alpha Delta sloper (160/80/40/30) off the tower and a straight 160 sloper off the other side. This is the only way I can get on 160.
There’s a new Par end-feed 40-20 dipole feeding the R40/20 QRP rig and it works way better than I had expected.
There are two six-meter squares on a second tower that work as well as a three element beam on 6 sans rotor.
Again if I had nothing I’d buy an S9 multiband vertical with an auto tuner attached to the base and a G5RV antenna for 80-10 if possible and the junior if not. Sure I’d miss 160 where very occasionally I’ve heard Europe and 80 which is my worst band by far but I’d be competitive everywhere else.
I’m considering adding an S9 31′ vertical to the front yard where it would sit next to the pine trees that line the yard and thus be invisible while in plain site and would work great for single transmitter, multi-op contests where I would want to run a multi station as well as a run station.
Look if it came down to it, I’d mount a vertical mobile TarHeel antenna on the car and run coax into the house and work the contest that way if I had to and I’d probably run a small 500-watt amplifier too 🙂
Regardless of the setup, you can have fun.