A simple antenna splitter

By Giovanni Carboni, IZ5PQT


This is a simple antenna splitter I built to connect an antenna to two distinct receivers.



I found the schematic diagram in the excellent article by John Bryant and Bill Bowers on dxing.info. Splitters are expensive if you buy them, but they are very simple to build. My unit is the one called DH-P in the article. The only substitution I did was to replace the binocular ferrite core 73-202 with a 43-202 I had handy. This perhaps explains why my splitter seems to perform slightly worse than the original DH-P at higher frequencies. Below the picture shows what is inside the brass box:




The primary has 12 turns of 0.35 mm dia. enameled wire while the secondary has 8+8 turns of 0.5 mm dia. The reason for the different diameters is just the different color of the wires! But don't try to use 0.5 mm wire everywhere, it won't fit inside the core.
The center of the secondary winding is grounded via a 27 ohm resistor.

The table below shows the results of measurements. I did not measure the impedance. Notice that an ideal passive splitter has an insertion loss of -3 dB. Here we have an extra loss of 1-2.5 dB up to 5 MHz, then the loss increases. The reason is possibly connected with non-optimal ferrite mix, but I find it fully acceptable for mediumwave and longwave listening. The isolation between the outputs is good.

Frequency (kHz)

Attenuation (dB)

Isolation (dB)

350
1000
2000
3000
5000
10000
15000
-5
-4
-5
-5
-5.5
-9
-10
-25
-26
-25
-25
-25
-24
-23
Measured characteristics.

HOME
© 1994-2014 Televideo.ws