Accurate 3 D EM simulations and precision machining

Accurate 3 D EM simulations and precision machining for low cost microwave and millimeter wave filters/diplexers Adam Abramowicz, Maciej Znojkiewicz QWED, Poland MWTG Telecom, Canada

Outline 1. Introduction 2. Segmentation and E-M simulations 3. Examples - 13 GHz and 15 GHz diplexers - filter and 26 GHz filter - filters for DBS Block Up Converters - combline X-band filter 4. Conclusions

• Application - low cost digital radio links. • Highly competitive market. • Low cost products rectangular waveguide technology • quick design and manufacturing cycle accurate 3 D electromagnetic simulation accurate CNC machining

• CNC vertical milling machines ± 40 microns accuracy internal rounded corners in E- and/or H- plane • ± 40 micron accuracy translates to ± 140 MHz frequency accuracy of a cavity resonator at 40 GHz. • Center frequency drift of a 40 GHz filter is 0. 96 MHz/C° • Design is a careful tradeoff between

• Fast, accurate and flexible design and optimization of waveguide components. • Cross-sections of arbitrary shape such as: filters, T-junctions, bends, lateral coax feeds • 3 D FDTD analysis (Quick. Wave) • S-parameter matrices are used in circuit simulator to optimize the relative position of the elements. • The advantage is mainly in shorter design time.

A diplexer with two asymmetric inductive iris coupled filters with integrated SMA-WR transitions and including an additional waveguide low pass filter is divided into two bandpass filters and two identical SMA-WR transitions, a waveguide low pass filter and a waveguide T-junction.

• 16 times bigger memory and 64 times longer time to compute the characteristics of the complete diplexer is needed in comparison with the filter only. • Quick. Wave 3 D - accuracy, - speed, - possible optimization using parametrized objects library - moderate price.

Library of UDO objects as shown below two resonator asymmetric inductive iris coupled filter with rounded corners is used in design and optimization.

13 GHz diplexer with metal post inside cavities, integrated low-pass filter and WR to SMA transitions

Measured RL characteristic of the 15 GHz diplexer (no tuning).

Measured characteristics of the lower channel.

Measured characteristics of the upper channel.

n=5, f 0=26 GHz Measured characteristics (without tuning).

n=5, f 0=26 GHz Measured characteristics (after tuning).

n=5, f 0=26 GHz, asymmetric inductive iris coupled filter with integrated waveguide bends

Initial characteristic of the 18 GHz (WR 62) seven resonator filter

Tuned characteristics of the 18 GHz (WR 62) seven resonator filter

18 GHz (WR 62) seven resonato r filter

Initial characteristic of the 14 GHz (WR 75) five resonator filter

Tuned characteristic of the 14 GHz (WR 75) five resonator filter

14 GHz (WR 75) five resonator filter

X-band comb-line resonator filter with stepimpedance resonators. Measured (continuous lines) and simulated (dashed

CONCLUSIONS • examples of the design and realization of X, K and Ka band filters and diplexers have been presented, • the design method is based on the 3 D electromagnetic simulations combined with the circuit simulations, • 3 D simulations take into account effects resulting from CNC fabrication like rounded corners of resonators,