Phasing out LF/NDBs With Closely Spaced Vertical Antennas
I wanted to try phasing in the LW frequency range using two closely spaced antennas and my Quantum Phaser to see if it worked. The antennas are two low-noise verticals (LNV) that are spaced at only about 85 ft/26 m apart - far shorter than the wavelengths of the signals being phased. The three NDBs seen in this video are AP 260 at Denver International Airport, BF 263 in Scottsbluff, Nebraska and 400 FN in Fort Collins, Colorado.
I show three demonstrations using two different receivers. I use an RTL2832 dongle with a Ham it Up Upconverter for the SDR receiver and a Rycom 1307A/GR for the analog receiver. Although I am able to phase out the signal 20+ dB I do not think it would be useful for NDB chasing as the null is so wide and the NDB signal so narrow. If it is due to the short antenna spacing then the null is most likely very non-directional and would not be useful for much of anything. It may (or may not) be fine for phasing out noise in the LW BCB. More experimentation is needed in the BCB as well as with multiple NDBs arriving from different directions. The Nebraska beacon is in the same general direction as AP at DIA is from my QTH so any directionality that nulled AP would also null BF 263 in Scottsbluff.
Software used is SDRSharp for the SDR and SpecLab to view the analog signals.
Note: When using the SDR and I put the phaser in you will notice the noise sound gets louder. This is due to the AGC on the audio which I neglected to turn off. So when the signal and nearby noise is actually reduced the AGC compensates and increase the volume gain.
Note: Sorry about the annoying reflection of my face on the laptop in the first demonstration. I didn't realize it was there until I posted the final rendering of the video and watched it on the laptop in full screen mode. YIKES!
