Antenna Magus Version 5.3 released! This release sees the addition of new antennas that focus in part on EMC measurement applications, as well as a number of small features and fixes. We encourage you to take the time to update to the newest version of Antenna Magus and hope you will find the additions useful! In this newsletter we will briefly look at some of the new antennas that have been made available. The new antennas are: Open boundary quad ridged horn antenna LPDA bow-tie hybrid antenna Biconical EMC antenna Wideband splash-plate antenna Single-grooved linear to circular mode converter Double-grooved linear to circular mode converter New antennas Open boundary quad ridged horn Image of the Open boundary quad ridged horn. The open boundary quad ridged horn is popular in EMC compliance measurements, and is often used when measuring radiation patterns of test antennas in an anechoic chamber. Total gain 3D patterns at (a) fmin, (b) 2 x fmin, (c) 3 x fmin, (d) 5 x fmin and (e) 9 x fmin. Although the antenna may be seen as a variation of the Quad ridged pyramidal horn, the propagating mode supported by the quad-ridged structure changes from TE (with sidewalls) to quasi-TEM when the sidewalls are removed. The operation mechanism or the antenna is therefore better understood by considering two planar Vivaldi antennas placed orthogonally to each other with co-located feed points. A major advantage of removing the sidewalls is that the on-axis gain dips prevalent in classic quad-ridged horns with sidewalls are eliminated - though the overall gain is generally reduced. The designed antenna achieves a VSWR below 3:1 over a 9:1 bandwidth with a relatively stable on-axis gain, especially considering its compact nature. At the upper end of the band the pattern shape does degrade to some extent. The gain typically varies between approximately 8 and 14 dBi across the 9:1 band. The antenna may be divided into two distinct sections — a coaxial-to-ridged-waveguide transition as well as a flared ridge section. The feed section aims at proving a good return loss for both vertical and horizontal polarization. Typical VSWR behaviour versus frequency. LPDA Bow-tie hybrid with square boom Image of the LPDA Bow-tie hybrid with square boom. The LPDA-bow-tie hybrid is - as the name suggests - an antenna combining an LPDA and a bow-tie. This antenna is widely used in EMC (electromagnetic compatibility) testing and is commonly known in the EMC industry as a BiLog, BiConiLog or bicon/log hybrid. The primary reason for combining a bow-tie with an LPDA is to eliminate band breaks in frequency sweeps during EMC testing, thus reducing test time and effort. At the lower end of the operating band the performance is that of an electrically small bow-tie (the S11 will be very high and the radiation pattern will be omnidirectional). At higher frequencies, the antenna will operate more like an LPDA (a higher stable impedance that is easier to match, with an end-fire radiation pattern). The LPDA bow-tie hybrid antenna with typical total gain patterns at fmin, fmin_lpda, 2.5fmin_lpda and fmax for an optimum performance. The S11 at the low frequency end can be improved through various means, such as resistive loading. When resistive loading is used, less elements are needed for the LPDA design. This approach, however, is not feasible for EMC testing as it introduces noise to the measurement setup. For this reason Magus allows two design options: ‘Optimum arrangement’ which uses resistive loading and fewer LPDA elements and ‘Optimum performance’ which has more LPDA elements, but no resistive loading. These two options are illustrated in the figures below, where the impact of the resistive loading can clearly be seen in the gain and reflection coefficient at the lowest frequencies.