Hasan Raza

Wideband Compact 4-Port Dual Polarized Self-Grounded Bowtie Antenna

We present a dual-polarized self-grounded bowtie antenna. The antenna is mechanically simple and wideband. One of the characteristics is its flexibility: it can be used either as a 4-port antenna in multiple-input-multiple-output (MIMO) systems or as a directional 2-port dual-polarized antenna in radar or sensor systems. The latter application requires a balun. The 4-petal geometry of the antenna has been optimized for the best matching to 50 Ω coax over 1.5-3 GHz. Both simulated and measured results are presented to verify the design. The antenna radiates over parts of the bandwidth similar to four Huygens source, one from each petal, each having directivity close to 4.8 dBi.

Measurement of Radiation Efficiency of Multiport Antennas With Feeding Network Corrections

Multiport antennas are widely used and often integrated with active components, such as low noise amplifiers, in antenna systems. It is important to verify and evaluate the radiation efficiency of a multiport antenna before being integrated in the system. When the radiation efficiency of a multiport antenna is measured, a multiport feeding network is always needed in order to provide the same antenna excitation as it is during its operation after being integrated in the system. This letter addresses how to measure the radiation efficiency of a multiport antenna excluding the losses in the feeding network used for the measurement, particularly when the impedance match between the antenna and the feeding network is not perfect. A rigorous feeding network correction approach is introduced by using measurement data of the radiation efficiency of the whole antenna with feeding network and the \mbi S-matrices of both the feeding network and the antenna. As an example of this approach, the radiation efficiency of a multiport Eleven antenna has been determined and verified against the simulated results.

Review of recent developments of the Eleven feed for future decade bandwidth radio telescopes

The Eleven feed is a compact, low-profile decade-bandwidth log-periodic dual-dipole array antenna. It has many advantages: a constant phase center location, constant beam width over a decade bandwidth, high BOR1 efficiency, low cross polar level and good reflection coefficient, all over a decade bandwidth. This paper reviews the recent developments on the Eleven feed technology, which covers several important issues for the applications of the feed in decade bandwidth radio telescopes.