I recently purchased a 2.4 GHz transverter from SG-Lab in Sofia, Bulgaria. To get you on air the transverter is shipped with a 2.3 GHz 4el HB9CV PCB yagi which at 2.4 GHz has a VSWR 1.7:1, that’s easy to fix. 🙂
In addition to using the supplied HB9CV PCB yagi, I will construct a 22el yagi (in progress) and the Bi-Quad directional antenna mentioned in this post.
You may recall I’ve had good results on 23cm 1296 MHz with a Bi-Quad antenna, also known as a double-quad antenna, so I hope to repeat similar results on 13cm 2.4 GHz. This post describes how I constructed a 2.4 GHz Bi-Quad directional antenna. The VK 2.4 GHz narrow band SSB call frequency is 2403.150 MHz.
13cm Bi-Quad Antenna
For dimensions see: Changpuak Bi-Quad online calculator
- Double-sided copper clad PCB 130 * 85 mm (I had this piece on hand)
- 50 mm length of semi-rigid 50 ohm RG402 (mini kits)
- Female SMA socket to RG402 (solder type)
- 300 mm length of 2 mm copper wire (junk box)
- 2 * 15.2 mm stand-off insulators. I used 7 mm diameter plastic sprinkler riser tube
- 2 * Cable ties
- PCB enamel
Prepare a double-sided copper clad board 130 mm * 85 mm. Drill the center of the board staring with a pilot drill 1.5 mm followed by a 3 mm drill bit. Use a taper ream to finish the hole.
Debur the hole and edges of the board.
Prepare a 1/2 wave length (43 mm) of 50 ohm RG-402 and a female SMA. RG-402 has a velocity factor of 69.5%.
Assemble connector to RG402 feedline
Prepare the Bi-Quad driven element, 30 mm per side.
Assemble driven element and feedline
Center of the driven element is soldered to the RG402 inner conductor. The two open ends are soldered to the RG402 copper shield
Almost finished – adjust the spacing between the reflector and driven element for a 1:1 VSWR. In this case to achieve a 1:1 VSWR the spacing is 15.2 mm, a small variation (0.4 mm) to the calculator dimensions table.
Spacers – 15.2 mm length of 7 mm plastic riser tube, measured with a vernier caliper. Solder the RG402 shield to the PCB front and rear.
Enjoy building your own 2.4 GHz Bi-Quad. 🙂
To finish off, below is a picture of the supplied 2.3 GHz 4el HB9CV Yagi. This antenna is designed for 2.3 GHz, at 2.403 GHz the VSWR is 1.7:1. To change the antenna’s resonant frequency to the VK SSB call frequency (2403 MHz) I trimmed 2 mm off each side of the two active elements (copper tracks). I left the director elements untouched.
First published: 19 February 2018
Last Update: 25 February 2018