Off Shoot Antenna
Posted on October 22, 2011
On the two threads comparing the AMT3000 to the new AMT5000 I used my ram-shackle window-frame antenna, which showed only that the AMT5000 goes a farther distance than the other one, but it did not show how far it can go with a much better antenna.
Meanwhile, still living in an imaginary world where an antenna can be built into the house in some way to radiate indoors and outdoors with some efficiency, I “decoupled” from the window and tried another approach.
I moved the AMT5000 1.5-feet to the left on its shelf, ran a 5-foot lead-in wire out a tiny hole at the base of an east facing window, found a corner where the clearance from ground to overhanging roof was exactly 10-feet, cut a 10-foot long bamboo pole supporting a 10-foot vertical wire, secured it in a standing condition right up against the window but electrically insulated, attached the lead-in at the lowest-point of the antenna, and tried to find peak. No luck.
So I put the 20 pF capacitor in line with the lead-in at the transmitter and found peak within toroid position S3, then went 1-full turn CW for that resonant spot.
R1 = mid
peak current = .5345
resonant spot current = .2465
Jumped in car and tuned radio to 1550 kHz, left the driveway onto the street and the signal went from full to weak background and didn’t even get halfway across the street. At the intersection no signal. On the next block it came back very briefly and was gone as I moved on.
Lesson: Though not perfect, the original window antenna works better than a 10-foot vertical wire against the back of the house.