TECHNOLOGICAL EDUCATIONAL INSTITUTE OF CENTRAL MACEDONIA DEPARMENT OF INFORMATICS & COMMUNICATIONS Master of Science in Communication & Information Systems Serres, December 2015 Nikolaos Loukidis Supervisor Dr.Tsitsos Stilianos Design of microwave binomial multi- section matching transformers

Abstract Scope and Objectives: In the proposed dissertation project, a microwave binomial matching transformer will be designed, simulated, constructed and tested for operation in the frequency range 0.5 – 1.5 GHz. Methodology: Review of the relevant theory and then design, simulate and optimize the circuit using the Advanced Design System (ADS) software package. Finally the circuit is implemented using microstrip transmission lines and its performance is measured using the Agilent E5071C microwave vector network analyser (VNA).

The microwave domain Microwave is a term used to identify electromagnetic waves above 10 3 megahertz (1 Gigahertz) up to 300 Gigahertz because of the short physical wavelengths of these frequencies.

Calculation of the electrical parameter values A= Δf/f 0 =85%

DESIGN OF MICROWAVE BINOMIAL MULTI- SECTION MATCHING TRANSFORMERS Section number (n) Characteristic impedance (Ω) 0Z 1 =95.76 Ω 1Z 2 =80.52 Ω 2Z 3 =62.09 Ω 3Z 4 =53.21 Ω

Substrate thickness H=1.575 mm. Conductor thickness T=0.017 mm. Relative dielectric constant Er=2.2. Dielectric loss tangent TanD= Conductor surface roughness Rough=0 mm. Conductor conductivity in Siemens/meter Cond=5.813e7. Line Width (mm) Length (mm) TL TL TL TL

Construction and results

Experimental measurements indicate that the value of the scattering parameter S11 (reflection coefficient) is dB (0.081) at 0.5 GHz and dB (0.114) at 1.5 GHz. These values are very close to the predicted values of 0.08 (see Fig. 5.4). Also S11 remains below -19 dB in the whole frequency operating band (0.5 – 1.5 GHz). In general the discrepancies between simulation and measurement are mainly due to the limited accuracy in the etching process used, the possible misalignments during soldering of the connector and also the quality of the connector and the RF resistor.

CONCLUSION In this work a multi-section matching transformer operating in the frequency range 0.5 – 1.5 GHz, was designed fabricated and tested. The circuit was initially designed using ideal transmission lines at a centre operating frequency of 1 GHz. A good performance of the circuit was achieved and the ideal lines were replaced with microstrip transmission lines. The new circuit was simulated and then fabricated on a PCB using a Tacoma TM substrate. With the help of the Agilent E5071C microwave Vector Network Analyser (VNA), the scattering parameters were obtained. By studying the experimental results, the performance of the multi-section matching transformer was verified.

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