The twin-lead Marconi antenna

In general, the Marconi antenna is a well-known type of antennas widely used by hams, and, in fact, is a Ground Plane antenna. In comparison to the regular Marconi antenna, the twin-lead modification is a short-circuited one.

The Half-Lambda T-antenna

The half-lambda T-antenna is a specific implementation of the T-antenna. The overall view of the antenna is shown in the picture below. The picture contains formulas as well.