Month: September 2021

Meander dipole antenna

It took some time from my first design on meander dipole antenna, but last weeks I made further progress. Meander dipole is electricaly same length as dipole antenna but meanders make it physically shorter and they are able shift impedance to the sweetpot of Smith´s diagram.

Fig. 1 – Antenna overview.

Big advantages of meander dipole antenna is near-perfect impedance match to power line and smaller size than physical. But of course there is disadvantage in lower radiation efficiency.

Meanders vs Relative Length
Fig. 2 – Number of meanders vs. length reduction.

It looses about 8-12 % of efficiency which can be 0.7 – 1.2 dB which looks horribly but it certainly nulls the loss on full dipole because of impedance mismatch 73 + 43j Ohms to 50 + 0j Ohms.

Further development was made on implementation of SMD baluns. Previous experiments with various types of ferrite rings were not successful. I discovered cheap wideband SMD made by MACOM [4] which is rated to 250 mW only. But if you dont mind over saturation of core it can work up to 4 W without heating HI.

Model was made in AntennaDesigner toolbox from MATLAB. You can see that simulation of Impedance in Fig. 3 is nearly perfect antenna.

Fig. 3 – Impedance of meander dipole antenna.
Fig. 4 – S11 parameter.
Fig. 5 – Radiation pattern.
Fig. 6 – PCB visualisation
Fig. 7 – Measuring S parameters on NanoVNA.
Fig. 8 – Balun placed on meander dipole PCB antenna
Fig. 9 – Trying to make rubber duck / donkey dick anntenna with meander dipole inside.
Fig. 10 – Final result looks better than it worked.
  1. https://www.mathworks.com/help/antenna/ref/dipolemeander.html
  2. https://www.qsl.net/kk4obi/Meander%20Dipole.html
  3. https://apps.dtic.mil/sti/pdfs/ADA617035.pdf
  4. MACOM / MABA-001759-000000
MABA_007159_000000-318068Download
meander_dipol_280M.kicad_pcbDownload