RTLSDR

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A subreddit for the low-cost software defined radio (SDR) community. While originally dedicated to the [RTL2832U USB rtl-sdr project, relevant content related to general SDR, RF, and similar projects are also welcomed.

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is an asphalt ground plane reflector equivalent to a grassy field ground plane reflector? (self.rtlsdr)

submitted 10 months ago* (last edited 10 months ago) by ch00f to c/[email protected]

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I’ve been working on improving performance and portability of my V-dipole for NOAA weather satellite reception.

Previously, I had the antenna mounted to a PVC pipe stuck in the dirt in my backyard at the appropriate 0.44~ish meters.

Today, I tried it in the front street with a new free standing mount. Despite being at the appropriate height, SNR was terrible unless I physically touched the antenna rod connected to the center conductor. Also, there’s already a ferrite choke on the cable close to the antenna.

I’m trying to work out how much could be different between my front road and backyard. Is it possible that the layer of asphalt is not acting like an appropriate ground plane mirror? Should I create a physical ground plane? For the record, grass was wet and asphalt was dry.

I’ve ordered a cheap NanoVNR to investigate, but in the meantime, I thought I’d ask since I only get so many chances to test the antenna.

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[–] [email protected] 3 points 10 months ago (1 children)

A ground plane needs to be conductive, wet soil with grass usually has ~1Ω per meter, asphalt is closer to 10,000Ω per meter.

[–] ch00f 1 points 10 months ago* (last edited 10 months ago)

Good to know, thanks!

I tried it again today with a section of chicken wire spread out beneath, but results were similar. I suspect my antenna's measurements are off somewhere.

Edit: Actually, looking back at the images, performance was definitely improved. I'm just kind of annoyed that touching the center conductor seems to vastly improve performance. It's a very simple antenna, and I've double checked all my measurements.