Newsletter 2017.2

Antenna Magus Version 2017.2 released!

Version 2017.2 sees a number of small new features and improvements, such as the reduced size and download time of our updates as well as a number of new antennas. This newsletter will highlight some of the new antennas that have been made available. For more comprehensive information please read the full release notes.

New Antennas

High data speeds and multiband operation of modern wireless communication systems have significantly increased the demand for broadband antennas that are capable of supporting such requirements. In general, the systems need low-cost solutions with desired performance in terms of impedance bandwidth, polarisation and gain. The five new planar monopole antennas added to Antenna Magus fall into this category and expand on the collection of wideband planar structures within Antenna Magus.

These new antennas (which brings the total number of devices in Antenna Magus to 321) are:

  • Planar Inverted Cone Antenna (PICA)
  • Teardrop-Shaped Planar Inverted Cone Antenna (Tear-Shaped PICA)
  • Leaf-Shaped Planar Inverted Cone Antenna (Leaf-Shaped PICA)
  • Rectangular Monopole with Trident Shaped Feed
  • Bevelled Rectangular Monopole with Shorting Strip

Planar Inverted Cone Antennas (PICAs)

PICAs are planar antennas with a semi-elliptical base and an inverted top installed above a ground plane. These antennas provide ultra-wideband (UWB) performance with radiation patterns similar to other monopole disc antennas.

The bandwidth of these structures is limited by the radiation pattern performance, since the azimuth radiation pattern does not remain omnidirectional at all frequencies. This performance problem may be addressed by improving the structural asymmetry, e.g. by adding a second orthogonal radiating plate.

Planar Inverted Cone Antenna (PICA)
Image of the Planar Inverted Cone Antenna (PICA).

While the impedance performance of the elliptical-base rectangular monopole already contained in Antenna Magus is better at the lower end of the frequency range, the PICA performs slightly better in the upper portion of the band.

Typical reflection coefficient
Total gain: fmin, 3.5fmin and 7fmin
Teardrop-Shaped Planar Inverted Cone Antenna (Tear-Shaped PICA)
Image of the Teardrop-Shaped Planar Inverted Cone Antenna (Tear-Shaped PICA).

The antenna consists of a semi-elliptical base with a modified inverted cone top installed above a ground plane. By tapering the straight line of the standard inverted cone using a spline fit through a number of defined points, a tear-shaped PICA is formed. While the teardrop shape does improve the performance marginally, it may not trump the increased manufacturing effort.

Typical reflection coefficient
Total gain: fmin, 3.5fmin and 7fmin
Leaf-Shaped Planar Inverted Cone Antenna (Leaf-Shaped PICA)
Image of the Leaf-Shaped Planar Inverted Cone Antenna (Leaf-Shaped PICA).

The addition of three holes in the radiating element of the standard PICA reduces the overall size of the antenna, by changing the current distribution on the radiating element surface. This size reduction is achieved, while maintaining an extremely wide impedance bandwidth.

The holes give the radiating element a leaf-like appearance, hence the name of the structure.

Although the impedance performance of the leaf-shaped PICA is slightly worse in the lower portion of the band, the width of the leaf is somewhat reduced from the original width of the standard PICA. The addition of a dielectric layer as part of the ground plane would also efficiently effect the impedance matching, since it varies the capacitances in the multiresonance circuit of the input impedance.

Typical reflection coefficient
Total gain: fmin, 4.5fmin and 9fmin

Wideband Planar Rectangular Monopoles

A planar monopole may be realised by replacing the wire element of a conventional monopole with a planar element. The standard rectangular (trapezoidal) planar monopole antenna (already included in Antenna Magus) consists of a rectangular radiator above a ground plane. The two new rectangular monopoles are variations on the standard version and are designed for improved bandwidth.

Rectangular Monopole with Trident Shaped Feed
Image of the Rectangular Monopole with Trident Shaped Feed.

This variation of the standard rectangular (trapezoidal) planar monpole antenna has a modified feed to achieve ultra-wideband performance. The three branched symmetrical (trident) feed leads to a more uniform current distribution at the base of the monopole element. This feed creates an intense vertical current distribution while suppressing the horizontal current distribution leading to better polarisation properties and impedance bandwidth of the monopole. A good reflection response (VSWR < 2 (S11 < -10dB)) across a bandwidth of more than 8:1 is achieved.

VSWR comparison between different monopole topologies
Total gain: fmin, 4fmin and 8fmin
Bevelled Rectangular Monopole with Shorting Strip
Image of the Bevelled Rectangular Monopole with Shorting Strip.

The antenna designed here is similar to the rectangular (trapezoidal) monopole in Antenna Magus. The addition of a monopole-to-ground shorting strip, and a bevelled shaped cut-out increases the operating bandwidth of the standard rectangular monopole (2:1) dramatically. The shorting strip counteracts the reactive nature of the rectangular monopole by adding inductance/capacitance over the frequency range. The bevel shaped cut-out further reduces the low frequency reactive component. A good reflection response (below -8dB) across a bandwidth of 14:1 is achieved.

VSWR comparison between different monopole topologies
Total gain: 1.125fmin, 3fmin, 7.25fmin and 14fmin