BA4JWC
Considering the link budget from four aspects: antenna, polarization, multipath, and blockage.
The antenna you are using might be the small, rod-shaped antenna that came with the walkie-talkie. This type of antenna is a short GP (wave length only about 0.1λ) in the 2m band, and its actual good GP antenna should have a resonant electrical size of approximately 0.25λ. It performs less efficiently than the 70cm band.
Furthermore, consider that a 2-meter wavelength is relatively long. If you are all in an urban environment, this will result in more significant polarization mismatch compared to higher frequency bands (i.e., electromagnetic waves reflect back and forth off walls and metal window frames, causing the polarization plane to randomly rotate. Even if you are both holding your radios vertically, the incoming signal may not be vertically polarized).
There is also the Faraday cage effect (such as in cars, aluminum alloy windows, etc., which create local cutoff points and block signals at a size of 2 meters).
Although it's true that the 2-meter band has better scattering performance than the 70-centimeter band, its Fienel radius is also larger. This means that if the first Fresnel zone is blocked, the area that is obscured will actually be even greater.
Furthermore, I also considered multipath fading (with an approximate 2m coherence bandwidth of 200-300 kHz), although I don't believe this is the primary cause.
The solution involves replacing the existing antenna with one that has a resonant size closer to the desired value, or using a high-gain antenna such as a Yagi (which is less portable). The goal is to establish communication in an open, unobstructed environment.
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