Newsletter 2019.2

Antenna Magus Version 2019.2 released!

Version 2019.2 includes 6 new antennas as well as various other extensions and improvements. This newsletter will discuss the new antennas and extensions that have been made available. For more comprehensive information on the update, please visit the full release notes.

New Devices

The new antennas (taking the total number of devices in Antenna Magus to 347) are:

  • Square Slotted Dual-band Patch Antenna
  • Wire Curl Antenna
  • Plano-Convex Hyperbolic Lens
  • Positive Meniscus Elliptic Lens
  • Traveling-wave series-fed patch array antenna with inset-fed patch
  • Microstrip to Slotline Transition

Square slotted dual-band patch antenna
Image of the Square slotted dual-band patch antenna.

The square slotted dual-band patch antenna is well suited to handle large amounts of data on fifth generation (5G) wireless networks with its dual-band operation. Additionally, it may be implemented in an array, to overcome high propagation losses.

The element radiates with right-hand circular polarization in two bands with moderate gain. Circular polarization has the advantage of reducing delay spread introduced by multipath effects.

For an input impedance of 100 Ω, typical bandwidths are 5.5 % and 3 % in the respective lower and upper bands.

Typical reflection coefficient versus frequency
Typical RHC gain at the lower (left) and upper (right) center frequencies
Wire curl antenna
Image of the Wire curl antenna.

The wire curl antenna produces a circular polarized wave (CPW) without the addition of problematic perturbation elements, which may have construction challenges at higher frequencies.

It is regarded as a simplified version of an axial mode helix (with a zero-degree pitch angle), or a single arm spiral antenna. The single curl element is typically arrayed for use in communication systems requiring CPW mode of operation.

This non-resonant device has a relatively constant impedance response. With the correct matching applied, to counter the reactive component, a good wideband reflection response can be achieved. An axial ratio bandwidth of 7% is achieved with good cross-polarization.

RHC and LHC radiation pattern at the center frequency
Axial ratio vs normalized frequency

Dielectric Lenses

The continued move towards millimeter-wave technology and increasing demand for higher frequencies has renewed interest in the use of lenses in communication systems.

The feedthrough characteristics of the lens antenna solves the blockage problem of standard dual-reflector antennas, enabling for a simpler design. The dielectric lens is analogous to a dual-reflector system with the surface facing the feed element considered equivalent to the sub-reflector, while the second surface is equivalent to the main reflector.

Both lenses transform a spherical wavefront into a plane wave, or conversely focus a beam from infinity onto one point. The hyperbolic lens, with one perfectly flat side, has the simpler geometry, while the elliptic lens, with inner spherical surface, creates a more homogenous wave with an associated higher efficiency.

A lens can substantially improve the performance of an antenna while it is also able to form the protective radome of an antenna construction. When fed efficiently from the focal point, the lens can produce a high gain pencil beam with low side lobes and good cross-polarization discrimination characteristics.

Plano-convex hyperbolic lens
Image of the Plano-convex hyperbolic lens .
Plano-Convex Hyperbolic Lens:
Typical total gain pattern at the center frequency
Plano-Convex Hyperbolic Lens:
Radiation pattern cuts at the center frequency
Positive Meniscus Elliptic Lens
Image of the Positive Meniscus Elliptic Lens.
Positive Meniscus Elliptic Lens:
Typical total gain pattern at the center frequency
Positive Meniscus Elliptic Lens:
Radiation pattern cuts at the center frequency
Traveling-wave series-fed patch array antenna with inset-fed patch
Image of the Traveling-wave series-fed patch array antenna with inset-fed patch.

Series-fed microstrip patch arrays are low profile, lightweight antennas typically used for communication systems, as well as in microwave sensor applications such as automotive radar. The traveling-wave series-fed patch array with inset-fed patch is related to the traveling-wave resonant series-fed patch array (already included in the Antenna Magus database). The patch elements of the traveling-wave array are spaced to produce a progressive phase shift between the elements. This results in a fan beam, which squints off broadside and scans with frequency. By replacing the load of the standard traveling-wave series-fed patch array with a matched inset-fed patch results in a more efficient structure requiring less elements for low gain designs.

The traveling-wave design can achieve high gain (up to 20 dBi) at a specified squint angle. As with most traveling-wave array structures (such as slotted guide arrays), the operating bandwidth is narrow (typically 2%).

Typical fan beam pattern for an 8-element array
Typical normalized E-plane gain pattern at the center frequency
designed for 15 dBi and a 10° squint angle
Microstrip to slotline transition
Image of the Microstrip to slotline transition.

The microstrip to slotline transition is an effective transition when the feed-path must change from one side of a dielectric to the other. The microstrip line and slotline are positioned orthogonal to each other. While it is cost effective and simple to manufacture, it still manages to achieve a wide 4:1 bandwidth.

Due to the nature of the slotline, a characteristic impedance of more than 50 Ω is often chosen to ensure the slotline is wide enough to be manufacturable. Both the microstrip line and the slotline terminate in radial stubs to increase the bandwidth.

Typical reflection coefficient versus frequency

Extensions

Combline microstrip stub array

The design of the Combline microstrip stub array (typically used in automotive long-range radar (LRR)) has been updated to design for a normal (perpendicular to the feedline) orientation of the stubs, in addition to the existing 45-degree (slant) design.

Typical radiation pattern at 76.5 GHz for the perpendicular (left) and slant (right) designs

Anchor Points

CST Studio Suite export models for connectors have been updated to include ports and anchor points. Furthermore, anchor points in all CST Studio Suite export models have been linked to a working coordinate system (WCS). This allows the user to select coordinate systems of interest for further modification of the model..

UFL Jack surface mount connector