Two Way radio difference - VHF vs. UHF?

Question

What is the good and bad between UHF and VHF. What is the reason to use VHF instead of UHF or UHF instead of VHF.

Answer 1

UHF vs. VHF

This is another misunderstood area of wireless systems. It’s generally accepted that UHF has greater range due to higher power output, and is less susceptible to television interference. Again, there is truth to this but there are other factors to consider.

Power Output

For example, in the VHF spectrum from 174 to 216 MHz the maximum allowable transmitter output power is 50mW. In the UHF band maximum allowable transmitter power is 250mW. Higher output power from the transmitter helps overcome dropout problems and increases operating range, but the sacrifice is shorter battery life. The actual effective radiated power is heavily affected by the individual transmitter’s antenna, so a higher output power does not necessarily mean greater operating range. Most high-quality VHF transmitters produce the allowed 50mW, for reliable operating range and reasonable battery life. UHF transmitter output power varies much more widely from one brand to another than VHF units. The maximum allowance of 250mW in the UHF spectrum is useful when maximum operating range is the prime concern. 100mW is commonly chosen for UHF transmitters as a good balance between operating range and battery life.

VHF & UHF

Wireless mic systems generally operate in several bands from 150MHz to 216MHz, which includes the VHF TV channels 7 through 13, or in the 470MHz to 806MHz UHF band (TV channels 14 through 69). TV channels 60 to 69 (746 to 806MHz) are being re-allocated, as of the date of this writing, for other applications. In addition, the band from 470 to about 516MHz is also being re-allocated for public safety applications. The demand for more spectrum usage is increasing while the available spectrum for wireless microphones is decreasing. Above the TV band is another part of the UHF spectrum from 902 to 928MHz. This upper UHF band is a "general purpose" band being used by a multitude of different applications ranging from garage door openers and amateur radio, to home-use cordless telephones. Generally speaking, the 902 to 928Mhz band is not a good choice for wireless microphone systems, especially for professional use in traveling applications. Interference is virtually guaranteed in this band. So again, it is unreasonable to assume that UHF is better by default.