RTL-SDR Blog V4 Dipole Antenna Kit

Introduction

Since this was all new to me and the price was relatively attractive, I picked up the RTL-SDR Blog V4 kit from Amazon. I am based in the US, so it was convenient and extremely quick. I also purchased a Raspberry Pi 5 to use for my amateur radio hobby to keep things separate and be able to tinker without having to constantly rebuild my home computer. If you still need to install your RTL-SDR Blog V4, I have a post for installing on the Raspberry Pi 5 you can reference.

Antenna Analyzer

When it comes to receiving radio signals, resonance is the key. For the RTL-SDR Blog V4, the blog itself mentions that exact lengths are not critical for strong signals. Ok, I can appreciate that. Early on in my amateur radio hobby, I picked up a Rig Expert Stick 500. This analyzer has a UHF (SO-239) connector on it and the RTL-SDR Blog V4 uses a SubMiniature version A (SMA) connector, so I had to pick up an adapter kit.

Antenna Lengths

The following lengths are based off of the kit that can be purchased from Amazon. The kit includes two telescopic antennas.

• 2 x 23 cm to 1 m telescopic antennas (Large Antenna)
• 2 x 5 cm to 13 cm telescopic antennas (Small Antenna)

Even after I get the lengths and orientation I want, I will still hook it up to the analyzer and test. The Standing Wave Ratio (SWR) has to be under 5 for the dongle to be happy. One thing to note is that the dipole antenna base includes two additional centimeters.

The lengths below are for one half of the dipole elements. Be sure to make both sides equal!

To convert centimeters (cm) to inches (in), divide the centimeters by 2.54.
100 cm / 2.54 = 39.37 in

Large Antenna

Sections	Length	Resonant Frequency
Five (5)	100 cm + 2 cm	~ 70 MHz
Four (4)	80 cm + 2 cm	~ 87 MHz
Three (3)	60 cm + 2 cm	~ 115 MHz
	47 cm + 2 cm	~ 144.39 MHz (APRS)
Two (2)	42 cm + 2 cm	~ 162 MHz
One (1)	23 cm + 2 cm	~ 285 MHz

Small Antenna

Sections	Length	Resonant Frequency
Four (4)	14 cm + 2 cm	~ 445 MHz
Three (3)	11 cm + 2 cm	~ 550 MHz
Two (2)	8 cm + 2 cm	~ 720 MHz
One (1)	5 cm + 2 cm	~ 1030 MHz
		~ 1090 MHz (ADS-B)
		~ 1500 MHz (L-Band)

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