Generation of conical patterns from circular patch antennas and their performance

The input and radiation characteristics of circular microstrip antennas operated at higher order modes to generate conical patterns are studied. The effects of varying the substrate parameters on characteristics such as radiation pattern, directivity, bandwidth, efficiency, and location of the feed-point to match a 50 ohm line are investigated. Also, a multi-feed technique to operate the antenna at any particular higher order mode is proposed. Successful experiments have used this technique to operate the antenna at the desired higher order modes and the experimental results are in close agreement with the theoretical analysis.