The circuit on this page serves as a Voltage Standing Wave Ratio meter or VSWR meter for the VHF-UHF-SHF frequency range. This includes the Wifi (802.11b/g), 2m, 70cm and 13cm Radio Amateur bands.
When building antennes for the Wifi band (Like the 8dBi omni), a need for an easy way to check the antennas arrose. A Voltage Standing Wave Ratio (VSWR) meter useable at the 2,4GHz band is however, hard to find. Meters like the? Daiwa CN-801S are expensive and need a minimum of 500mW (27dBm) power to function correctly.
The device consists of two parts. One RF head and a (preferably analog) indicator. The meter has a 9 Volt alkaline battery power supply. The indicator on top is used to read the VSWR. The first switch is used to switch the power. A green low-current (2mA) LED illuminates when power is applied to the circuit.
The second switch is used to switch between slow (peak-hold) and Fast mode.
Below, the last control is the Sensitivity pot. It is used to adjust the meter sensitivity to the RF source used, such as a Wifi Access Point, or VFO. RF Input power must be somewhere between 15 and 20dBm (30 to 100mW)?
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