Mini Quadrifilar Helix for Weather Fax

Looks like the answer is Yes,

From the IEEE:

Abstract

The design is described of a very compact quadrifilar helix antenna. A hollow ceramic rod is used as a dielectric load to reduce antenna size, which is only 2.7% of an air-loaded quadrifilar helix antenna. A simple equivalent circuit is established for the proposed quadrifilar helix antenna to demonstrate impedance characteristics. A self-phasing method for achieving circular polarization is also proposed. This method is convenient for tuning circular polarization. Additionally, a compact matching structure is designed to match the proposed antenna, which only utilizes short transmission-line sections and one capacitor. For experiments, the proposed antenna is designed at 1.575 GHz such that it can be utilized for global position system. Measurement and simulation results agree. A hemispherical pattern with a beamwidth of 150^deg is measured. This circular-polarized pattern with a wide beamwidth is feasible for mobile applications.

...but for your frequency range it will be approximately 11 times bigger!

Oh well, I am just going to have to build a full sized one and hope for the best.

The 137.1 is the satellite down link frequency. I don't think you need anything that exotic. As you can pick it up with a handheld radio, I would guess that a basic omni antenna that can "see" much of the sky. IIRC they are in a polar orbit.

I tracked it on the ship using an AN/WSC-3. I "heard" the signal for not much more than 10 minutes as I recall. I was using an omni antenna for VHF aircraft comms. I think it had -.5 db of gain. I tried using the "trashcans" in port, but they were too far off freq. Never got around to using another antenna. However, I wasn't able to decode it reliably. What software are you using? You could try a 2 meter YAGI mounted to a stick and record the signal and then play it back.

I was using APT Decoder and the 1 minute that I was able to pick up on my Baofeng UV 3R with its dual band antenna came out very garbled with only the faintest of shapes visible.

Make your own quadrifilar helix antenna

Mini? Not sure how small you want it.

About the size of a toilet roll tube.

Have a go at it. Just use 1/2ⁿ lengths of the original design for your elements.

Here's a tidier design

This is an alternative to quadfil helix APT antenna.

What you need is gain. Surprising you even got a sniff before.

Enjoy.

Noaa 15 will be passing over soon. I have made a helix antenna and will go outside with the radio and laptop and see what I get.

I was able to pick up the satellite very clearly for a few minutes. The problem was, I had the record level on the line in set too high so the picture came out as unrecognisable messy greyness.

I will see what I get with Noaa 17. The poweline networking adaptor in the house strongly interferes with 137.5 and can be heard as a constant clear tone until I turn it off.

Turn it off when you record the next time.

How big is the helix you just made?

It is actually a long wire on the end of a wooden stick which I go outside with and it picks up the satellite very clearly. There are no satellites around at the moment though.

How is the wire actually connected to your receiver? Ballun? Coax? Loose coupled? Clipped?

What you have there is a "long wire" or Beverage antenna. These have gain.

1 or 2 wavelengths long is recommended in the implementation section

A little bit of gentle theory here.

Beverage antenna can't be bad with a name like that.

The wire is just stuck in the hole in the middle of the SMA connector. The other end is secured onto a wooden pole so I can move it around to get the best signal. I took the laptop outside with me so I can record the sound.

If you improve the transmission line to antenna interface you may get even more of the picture without having to go the way of the helix.

Here is another image. I got this one when I went out into the back garden. The antenna I am using is just a 1 metre long piece of wire. The bandwidth of my radio is also not wide enough which results in the noise on the bright parts of the image.