The realization of IDGH gain rhombic antenna in the UHF band using tapered U-shaped arms

摘要

In the early days, the rhombic antenna gained favour because of its wide band frequency characteristics. This type of antennas was first introduced in the early 1930's [1], They were used primarily in the HF band. Until recently, travelling wave rhombic antennas have never been seriously considered for the use in the UHF band where they may have many advantages over the standing wave antennas [2]. A previous study [3,4] of the travelling wave V-antennas revealed that these antennas do not lend themselves to increase in the directional gain by increasing the length of the antenna arms indefinitely. This was attributed to the radiation of most of the power from the input end of the antenna leaving relatively low power to be radiated from the far ends. A similar study showed clearly that the end sections of the arms of tubical travelling wave rhombic antennas do not radiate appreciably and the directional gain of the antenna cannot be increased by increasing the arms of the antenna beyond a certain limit.