That tuning off frequency act like sort of attenuator.
Device usually present in "real" dedicated homing receivers.
The method you are using is the standard one for "passing by" aircraft, or "better than nothing" method.
Now days it is not necessary to use expensive high end dedicated equipment 30-40 k USD value,
because even the modern "el chipo" SDR multi channel phase coherent receivers can do the job.
Here example on one of recent examples funded by Crowd Supply
https://www.crowdsupply.com/krakenrf/krakensdr
Device can be fit within one pelican case, running on own battery power, antennas on top,
all strapped to the back seat bench - not necessary to do any major (to much paperwork) modification of aircraft.
Personally I tested (on purpose & for fun) 2 channel SDR called LimeSDR USB,
and even that is much better than standard Air Band transceiver use.
SDRs are digital toys so even direct decoding of 406 MHz ELTs data is possible. On the other hand the search for cell phones
out of range (of standard base station) is possible too. All with proper SAR licensing at local national level agency.
Search approach is to mimic real cell base station, that lost cell phone is happy to answer in case the power is still present.
The search pattern in that case must be for example within 30 km distance, because of timing limitations of that network which is theoretically 37,5 km.
Just my 0,02 $ & have a fun...