The flat GP

Ground plane antennas are one of the most common antenna type. To achieve an omnidirectional radiation diagram they don’t need to have more than two coplanar radials. This is easily demonstrated simulating the antenna. Each wire has a quarter wave length. Frequency is 14.15 MHz, center of antenna is five meter above real ground and wire diameter is 1.5 mm.

flatgp20

The sloping wires form a 120 degrees angle respect to the vertical wire. The radiation diagram is almost omnidirectional in the horizontal plane while it is well shaped in the vertical plane and good for DX. The antenna doesn’t need matching since its feed impedance is very close to 50 ohm.

flatgp20irr

I needed to simulate this antenna at low height. If height above ground is increased, vertical radiation pattern changes, less peak vertical lobe angles are obtained. The flat GP is easy to build because of its coplanar structure.

Leave a Comment

Your email address will not be published. Required fields are marked *