Characterizing the SWR of an Antenna with a Noise Source and an RTL-SDR
In our last post Adam Alicajic showed us on YouTube how to determine the frequency response of an RF filter using just a wideband noise source an LNA and an RTL-SDR dongle.
In his latest video Adam shows how the SWR of an antenna can be measured using almost the same low cost equipment. One additional piece of hardware required to measure the SWR is a directional coupler which can be bought on Ebay for about $10 USD.
SWR stands for “standing wave ratio” and is a measure that can be used to tune an antenna for a particular frequency. The closer the SWR is to 1:1 at the designed antenna frequency, the better the antenna will receive (and transmit).
In his video Adam shows how he measures the SWR of an ADS-B antenna which he has built and is selling. His results show that the antenna has an SWR of 1:1.02 at 1090 MHz which is quite good.
The directional coupler linked is 800-2500mhz, most others on ebay are much wider on the lower end. Would this coupler work in the VHF and UHF ranges?