The morgain antenna is a no-trap multiband antenna
This antenna originally designed in the U.S. was born as an antenna for 40 and 80 meters and has been adapted for 20 and 10 mand can have excellent performances on the 15 meters, with a total lenght of 20 meters.
The picture shows the Morgain dimensions: the measures are not original but they are the best measures that have been obtained from several Morgain tests.
The wire used is copper 2 mm square covered in vinyl.
Tuning the Morgain Antenna
Calibrating procedure consist in moving the jumpers AA for the 80 meters, and jumpers BB for the 40 meters.
To calibrate , prepare 4 wire jumpers , 12 cm long, with connecting pins at the ends.
You start by inserting the pins ( with the relative jumpers ) in the lenghts listed, then raise the antenna in the working elevation and trace the SWR.
If this is not acceptable, move the jumpers a little at a time until you will reach an SWR close to 1:1.
At this point, after having taken notice of the exact distances, replace the jumpers with new jumpers that will be soldered and insulated .
You will notice immediately , from the first movements that there is a significant interaction between the calibration of 80 m and that of 40 m, so make tuning by for short distances.