  We generalize the recently proposed $\mathcal{PT}$-symmetric axion haloscope
to a larger array with more $\mathcal{PT}$-symmetric structures. The optimized
signal-to-noise ratio (SNR) has a greater enhancement, as well as the signal
power. Furthermore, we show that the robustness of the detector towards the
variations of the array coupling is the strongest when a binary tree structure
is introduced which contains a largely enhanced $\mathcal{PT}$ symmetry. The
multiple allowed probing sensors can further increase the SNR by a factor of
sensors' number due to the correlation of the signals. This type of array can
strongly boost the search for axion compared to single mode resonant detection.
The enhancement to the SNR becomes the most manifest when applied to the newly
proposed detection using superconducting radiofrequency caivty with AC magnetic
field where most of the parameter space of the QCD axion above kHz can be
probed.
