London — The Soviet Union appears to be making strategic miscalculations in northern Europe. This is the view of experienced Nordic diplomats as they study the implications of two recent events:
* The continued intrusion into Swedish waters of what are assumed to be Soviet submarines. Following a parliamentary commission report in May listing more than 40 intrusions last year, a Swedish military report just issued in Stockholm says alien submarines, many of them mini-subs, violated Swedish waters between 20 and 40 times in the summer of this year alone.
* The Soviet action in shooting down the civilian Korean Airlines 747 airliner in the Far East.
One immediate Scandinavian reaction to both developments is that the Soviets are, to say the least, extremely inconsistent.
Says the former permanent head of the Swedish Foreign Ministry Leif Leifland, who is now Swedish ambassador to London, ''The Soviets claim the right to violate Swedish territorial waters - but they say that if anyone violates their own sacred airspace, he must take the consequences.
''When their submarine was caught on the rocks near Karlskrona in October 1981, they said we had no right to board it. But, when a civilian airliner flies into their airspace, they say they can shoot it down.''
The contradiction is being noted across Scandinavia these days, making Moscow more unpopular there than ever.
A long-term Soviet aim in northern Europe, Nordic diplomats say, is to upset the delicate balance around the Baltic Sea and remove the threat of NATO nuclear weapons ever being stationed there.
Such a removal would allow huge Soviet submarines, armed with intercontinental weapons, to move more freely westward from the massive Soviet naval base in Murmansk, north of the Arctic Circle.
Currently, Denmark and Norway, both members of NATO, refuse to have NATO nuclear weapons on their soil - unless hostilities break out. Then both countries will permit NATO to bring them in.
Yet, by refusing to stop sending submarines close to Swedish shores, and by shooting down the Korean airliner, Moscow is not weakening but strengthening Nordic determination to resist Soviet rhetoric, policies, and persuasion.
Ambassador Leifland said in an interview here, ''Sweden's historic neutrality will continue, of course. Our people want it.
''But these repeated submarine incursions mean that the Swedish government and people are much more than a sideshow now.
''We are part of the European theater.
''It doesn't mean that there's the immediate risk of a Soviet attack. But the intrusions are making Sweden spend millions more kronor on defense. It is reallocating money from Army to anti-submarine warfare. . . .''
Still puzzling Stockholm, Oslo, and Copenhagen is just why alien submarines, universally assumed to be Soviet, keep violating territorial waters.
Theories abound, but certainties are few.
The latest official report, from supreme commander of Sweden's armed forces Gen. Lennart Ljung, said intruding submarines are apparently being more careful now. They are leaving no ''imprints'' on the seabed (tracks from a mini-sub apparently able to ''walk'' on the seafloor were found last year) and are avoiding Swedish radar.
Monitor contributor David Brown in Stockholm says the latest report, which did not use the word ''Soviet,'' made the front pages of the major Stockholm newspapers, but made less of an impact than a parliamentary report in May which did point directly at Moscow.
Some experts see the Soviet military training crews for quick-strike landings if war comes. Small teams could knock out Swedish command centers en route to hitting NATO airfields in northern Norway.
''Whatever it is, it is systematic,'' says another Nordic diplomat here. ''It is blunt and heavy-handed. So far Sweden has only caught one submarine (off Karlskrona). But they are using depth charges now, and they have new torpedoes.
''Sooner or later they'll catch another sub. Is that what Moscow really wants?''