Most people who are reporting they don't suffer from signal degradation when bridging the antennas indicate that they remain at 5 bars before and after, and therefore the issue is not affecting them. However, this can be attributed to the fact that the initial signal strength is already very high, and the range over which 5 bars is displayed is also relatively large compared to the range of 1-4 bars. What this means is that depending on the initial signal strength, a 100x increase in noise (potentially caused by bridging the antennas) can cause the signal to remain at 5 bars if there is initially a strong signal, or it can cause a drop from 5 bars to no service if the initial signal strength was near the threshold between 4 and 5 bars. This means that the only meaningful test to disprove the signal degradation needs to be conducted in an area in which the initial signal strength is at 4 bars. If your phone truly does not suffer from this effect, then it will remain at 4 bars even after bridging the antennas.