# 40 m band – Hairpin antenna – Theme with variations (part 2 of previous article)

After 2 weeks of testing the Hairpin antenna for 40 m band (the light model with Cu wires), it’s time to build the regular prototype with Al tubes. But, first off all, let’s play with MMANA- GAL to see what are the limits.

The main differences between classic Hairpin antenna and this model are:

• The antenna is mounted on a metalic grounded mast.
• The spacing between arms is larger to obtain a wider antenna

Now, let’s play with parameters.

1. Spacing

Aluminium tube diameter = 24 mm
Hairpin length = 3 meters
Height from the ground = 4 meters
Ground setup = 14 / 5
Q capacitors = 500
R =50 ohms (+/- 1)
jX = -1 /+1 ohms

Higher spacer, better gain and Bw

2. Aluminium tube diameter

Spacing = 24 cm
Height from the ground = 4 meters
Hairpin length = 3 meters
Ground setup = 14 / 5
Q capacitors = 500
R =50 ohms (+/- 1)
jX = -1 /+1 ohms

Higher tubes diameter, better gain and Bw

3. Q capacitor

Spacing = 24 cm
Height from the ground = 4 meters
Hairpin length = 3 meters
Ground setup = 14 / 5
Aluminium tube diameter = 24 mm
R =50 ohms (+/- 1)
jX = -1 /+1 ohms

Vacuum capacitor (High Q), high gain but narrow Bw

Regular air capacitors, lower gain but wider Bw

4. Height from the ground (grounded mast length)

Spacing = 24 cm
Q cap = 200
Hairpin length = 3 meters
Ground setup = 14 / 5
Aluminium tube diameter = 24 mm
R =50 ohms (+/- 1)
jX = -1 /+1 ohms

More height, more gain and Bw

5. Hairpin length

Spacing = 24 cm
Q cap = 200
Ground setup = 14 / 5
Aluminium tube diameter = 24 mm
R =50 ohms (+/- 1)
jX = -1 /+1 ohms
Height = 4 meters

Too short, less gain. Too long, you can not tune the antenna (value of Cv1 will drop to parasitic capacity, or to zero)