Today I investigated the shroud mounted antenna which is installed on most CFM Shadows.

Here is a photo of Georges’ antenna. The antenna has been installed for many a year with the hoop as the ground plane. I thought it worked well. I suppose it did its job as most of the installations out there do but little did I know. The difference is the acceptance of the white RF noise as normal but very draining and is something we all put up with. It can be a lot better! A bit like alcohol free beer…..

Measurements taken standing next to the cockpit. Yes this makes a diffrerence!

Sitting in the cockpit with the canopy OPEN.

Sitting in the cockpit with the canopy CLOSED.

Canopy closed and wearing a headset

I spent the whole day messing about with it but sadly could not get any stable results. Just as with the handheld radios, the person is a major contributor to the ground plane.

Bottom line is each configuration will require the pilot to sit in it and tune the aerial accordingly. I’m happy to do this but the real answer is a stable antenna which resonates with its ground plane correctly. The stable antenna will require less battery power and 5x the range AND knock out the white noise of its unstable ground plane!

I’ve got to end with a golden nugget!

**GOLDEN NUGGET** – All wires, rods, airframes etc all are antennas!

Heads Up!

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6 Responses

  1. Ray, Ralph Chesters used my original Shadow BD to develop his Communica system. He fitted the aerial about 300mm in from the tail end of the boom (which acted as the ground plane). Reception on that aircraft was outstanding and I repeated the layout on my Streak G-WESX. Can’t say we ever used an SWR meter in those days, but it worked just fine.

    • Hi Nigel. It comes to beer with alcohol or not. They both are beer! Having the kit proves things a bit better. I’ll most probably come across one of those installations and go from there. But most of what has been tested needs some modification. The dipole antenna on the boom of George is what I’m going to test next. Thanks for you support. Ray

  2. What happens when you turn your head wearing headsets? If the passenger and pilot different ways? Do my spectacles frames become an aerial?
    Aaaaaaah!

  3. Antenna
    We too mounted the antenna on the boom of a Star streak always worked well
    My own shadow has it on the shroud with a square of foil underneath as a groundplane
    Often wondered from a health perspective having this over your head or is it totally safe
    Keep up the good work Ray

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