DIY – 137 Mhz V-dipole antenna for weather satellites reception
D.Prabakaran VU3DXR
A V-dipole for NOAA weather satellites on 137 MHz has been published by 9A4QV and it seems to get very good results. The designed antenna works at frequency 137 Mhz with omnidirectional radiation pattern.
The length of the each leg should include the connecting wire’s length up to the coaxial connector or coax. For my case connecting wire’s length is around 6 cm for convenience. Here in my case, PVC end cap acted as antenna elements mount, which is structurally stable than electrical terminal block.
I have used the following materials:
⦁ PVC pipe – 2 inch diameter
⦁ PVC pipe – 2 inch end cap
⦁ Aluminium or brass elements(one end threaded) – 2 nos each length 530mm
⦁ 8mm Brass stand off nuts and bolts – 3/4 mm size – 2 nos
⦁ BNC female connector adopter
⦁ solder lugs with 6cm wire soldered – 2 nos
Procedure
1. Fix brass stand off nuts on PVC end cap at 120 degree apart using bolts along with solder lugs.
2. Insert both antenna elements into brass stand off nuts and firmly screwed it.
3. wires from solder lugs connected to BNC female connector adopter
4. Fix PVC end cap on top of PVC pipe.
5. The length of the each leg should include the connecting wire’s length up to the coaxial connector or coax plus length of stand off nut.
6. Stand off nut length should be minimum 8mm
With this antenna, i captured two NOAA satellite passes just above my location. Images are given below. During second pass, another sat meteor-m2-2 caused lot of qrm after 75% of decoding.
My nanovna sweep show resonance at 133mhz,which near to required 137 mhz. i need to trim antenna little bit to obtain resonance at 137.5mhz.
Receiving NOAA-19 Automatic Picture Transmission (APT) signals presents an exciting opportunity for radio enthusiasts to explore satellite communications while experimenting with antenna designs. The V-dipole antenna configuration offers a practical and effective approach for capturing the 137 MHz weather satellite transmissions, combining simplicity with surprisingly good performance.
The NOAA-19 satellite, part of the Polar Operational Environmental Satellites (POES) program, transmits continuous weather imagery on 137.100 MHz using the APT format. This analog signal contains visible and infrared Earth imagery that can be decoded using readily available software, making it an ideal target for amateur satellite reception experiments.
The experimental V-dipole antenna design represents a departure from the traditional turnstile or QFH (Quadrifilar Helix) antennas commonly used for weather satellite reception. By positioning two dipole elements at an angle to form a “V” shape, this configuration creates a broader reception pattern that can effectively capture signals from satellites at various elevation angles during their passes.
Construction of the V-dipole involves creating two half-wave dipole elements, each approximately 53 centimeters long for the 137 MHz frequency. The elements are typically positioned at angles between 90 to 120 degrees, with the optimal angle depending on local terrain and desired coverage pattern.