Any aliens within about 70 lightyears can easily infer a technological civilization on our planet by analyzing our television and BMEWS radar signatures.
Not really correct because the signals would so weak as to be undetectable at those distances.
Drop a pebble into a completely calm lake and you can only observe the ripples radiate out so far until the energy of the pebble impacting the surface is so diffuse you can no longer see the effect on the water (ripples).
Radio waves behave similarly. Earth based radio transmitting stations do not transmit enough energy to overcome the vast distances of inter-stellar space due to path loss.
Path loss is the reduction in power density which occurs as a radio wave propagates over a distance.
Every time you double the distance, you receive only one-fourth the power. Assume an television station in 1970 transmittd omni-directionally at 100 kW. The signal is now ~51 light years away but because the signal radiates outward like ripples on a pond, the 100kW is now stretching out over an arc length of 320.4 light years.
The amount of energy received at any signle antenna 51 light years away will be so low as to be undetectable.