Nhờ sửa bài giúp

One of the main problems to solve when designing printed antenna devices equipped with a power divider is that when radiators placed in the same plane with a divider a good isolation between ports is hardly achievable due to mutual coupling of radiators and a divider.

This drawback can be tackled either by increasing space between radiators and a divider or by placing radiators and a divider on the different sides of the substrate.

In both cases, it is not guaranteed that when changing the topology of antenna it is possible to save radiation characteristics.

On the other hand, when increasing elements spacing the input impedance of the antenna can change and, hence, would need to be tuned again.

There have been a few reports that have considered the influence of power divider on the antenna characteristics, when radiating elements of the antenna were placed orthogonally with respect to the divider.

However, the design of a ring power divider itself requires taking into account undesirable parasitic radiation effects when divider radiates electromagnetic waves.

Another issue occurs because of poor matching between power divider and radiator.

In this case power from a divider rejects from the radiators and propagates toward the source.

There are many designs of multiple port devices in which authors focus on solving such problems.

In this work, we integrated two terminal-fed dipole radiators with a ring power divider.

The proposed antenna is shown in figure 1.

As can be seen from this figure, the radiators and a ring power divider are placed on the same side of the substrate with relative permittivity 2.5.

However, in contrast to the papers mentioned there is a printed balun, placed at the bottom side of the substrate, which works both as a balancing unit for dipoles and as a ground plane for a power divider.

The space between dipoles is much lesser than a half of the wavelength.