Hi Ray,
The classic source for Fresnel zones as they apply to HF site selection is NBS Technical Note 139: https://nvlpubs.nist.gov/nistpubs/Legacy/TN/nbstechnicalnote139.pdf While Technical Note 139 applies primarily to horizontally polarized antennas mounted above the ground, its general conclusions apply to 1/4 wavelength 160 and 80 verticals mounted on the ground. The outer edge of the Fresnel Zone is several kilometers for low angle radiation from 1/4 wavelength 160 and 80 meter verticals, especially when the verticals are installed on a highly conductive surface ( e.g., sea water, salt marsh or wet marshy soil ). The outer edge of the Fresnel zone is much closer when 160 and 80 meter 1/4 wavelength verticals are installed over a low conductivity surface (e.g., dry, chalky or sandy soil). 73 Frank W3LPL ----- Original Message ----- From: "Ray Higgins" <ray.w...@gmail.com> To: topband@contesting.com Sent: Thursday, April 18, 2019 2:48:57 PM Subject: Topband: Fresnel Zone I have two questions about fresnel zone. I just purchased 22.5/ac near the ocean near Machiasport, ME. This is in the Northeast corner of Maine about 30 miles south of Eastport and a Lubec. This is going to be my personal Remote Contest station! I plan to be contesting from this new qth starting in 2020 but will be QRV by mid 2019 for testing. This qth is anywhere between 1-3 miles from the ocean or the bay, it sits on a high plateau 150ā asl thats slopes in all directions to saltwater (peninsula) except N/NW. The property has a saltwater river and marsh that runs the perimeter from south to north favoring the NE direction, the marsh is only 50-100' wide and 1500-2000ā away from the property. The land has a gradual slope to the marsh. My questions: 1.) Is the saltwater river bed/marsh wide enough to be an effective field in the Fresnal Zone? 2.) What is the wavelengths needed to be within the Fresnal zone of a river/marsh compared to an ocean? In this photo album (last pic) I have outlined the river saltwater marsh and property boundry from a google earth shot. https://photos.app.goo.gl/ui79t2jFo95b29et6 Iām only concerned about 80 and 160m in the Fresnal Zone. Any input would be welcomed. Thanks, Ray W2RE Sent from my iPhone _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector