6. Antennas for air bands / Dipole vs discone
The photos show a new dipole and the familiar D190.

My place and Haneda airport are apart 40 km, of which 2/3 is on the sea and the rest on a flat land. To Narita, 22 km on a flat terrain.

The calls of Haneda tower are sometimes heard and other times not. So far I have used Diamond D150, D190, D220 (for mobile use) and also much larger one D1300AM. As far as I hear Haneda 119.1, their peformances are more or less the same (by some reason, the smallest D220 looks somewhat better than the others).

Even if the used mode is AM, the mere 40 km does not seem to justify this poor reception. Althouhg discone antenna is versatile for wide range application, its gain for a particular frequency might be not so good. So I tried a wire dipole of 60 cm + 60 cm suspended from the window frame of my shack. The voices of Haneda tower are clear and loud all the day! This resulted in this dipole.


Aiming at Narita 118.2 and Haneda 119.1, I made the dipole of 120 MHz with the shortening coefficient of 95%. The calculated length seemed a bit longer and 58 cm + 58 cm gave the intended result. Different from the wires, the pipes seem to give a rather higher shortening coefficient.

Now I enjoy listening Haneda as well as Narita steadily as background sounds.