In the scope of broadband radiators, the biconical antenna, or its monopole conical counterpart, is long known to be a proper choice. One common form of such radiator, the spherically capped conical antenna (SCCA), has closed-form solution to its input impedance, from which the broadband performance potential is easily verified. Nonetheless, from the design perspective, apart from a few clues inferred from existing solutions, little is found to accurately guide the choice of the main geometrical parameters of the antenna that will enable it to comply with a set of imposed bandwidth requirements. This paper proposes a simple 10-step sequence to derive conical or biconical antenna design charts. These charts provide straightforward information on the geometrical limits within which the required antenna impedance matching broadband performance is achieved. The method is assessed for the SCCA and the open conical antenna (OCA) using theoretical and simulated estimates of the input impedance. A discussion on the impact of the cap and the feed gap is included.

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Since the MIMO technology presents antenna arrays that can be formatted with tens to hundreds antenna elements, several effects arise due to this array structure, such as mutual coupling and impedance matching among antenna elements in the array. The treatment of these issues seeks to solve problems such as the performance degradation of communication systems. In this context, this paper proposes and evaluates three strategies of joint decoupling and impedance matching networks (DMN) for antenna arrays. The first method, called DMN with Lumped Elements (DMN-LE), performs the decoupling and impedance matching steps with capacitors and inductors. The second method, called DMN with Ring Hybrid (DMN-RH), utilizes a microstrip line in a ring format. The third method, called Networkless Decoupling and Matching (NDM), brings a concept of decoupling without the presence of a network itself, which enables modeling an antenna array that performs DMN operations in a simplified and compact manner. A comparison of the methods is performed both analytically and via computer simulations. The figure-of-merit for this comparison is the antenna bandwidth, for which both matching and decoupling are measured against S-parameters below a given threshold. We conclude that the third method is a promising new alternative approach.