I am looking for guidance to help fringe reception of vhf marine transmissions. The distance I am trying to span is around 18-20 miles and I believe there is a slight hill breaking the line of sight along the way. I am limited to attic mounted antennas (wood, shingles, no metal). I am using runs of commscope rg6 that spans 70-100 feet depending on location in the attic. Loss is around 2-2.25 dB per the data sheet. I am working with a few radios: RS Pro 2032, Pro 95, PSR 800. With my attic mounted tram discone antenna I cannot receive any maritime signals.
As a test case I built a 5 element yagi that spans 150-165 MHz. It was designed for 75 Ohm to match the rg6 and at 157 MHz it is modeled at 9.5 dBi realized gain. The cable run is around 100 ft. I have no way to verify the gain but it’s measured vswr at the antenna input matches up nicely with the model. Testing the front to back ratio against NWS transmitters seems reasonable.
I mounted the yagi and pointed it in the desired direction. I now receive some signals including a coast guard station, a commercial land-based maritime transmitter, and very limited ship transmissions. For the signals I do receive I can tell what they are saying but the signals are generally weak and noisy. I am not expecting too much based on my location and installation limitations but I would like to see if I can clean up the signals I do receive and possibly get some more.
I am considering my options to try to improve reception. Ideas:
I am seeking advice for my situation and for prioritizing what to try next. Thank you.
As a test case I built a 5 element yagi that spans 150-165 MHz. It was designed for 75 Ohm to match the rg6 and at 157 MHz it is modeled at 9.5 dBi realized gain. The cable run is around 100 ft. I have no way to verify the gain but it’s measured vswr at the antenna input matches up nicely with the model. Testing the front to back ratio against NWS transmitters seems reasonable.
I mounted the yagi and pointed it in the desired direction. I now receive some signals including a coast guard station, a commercial land-based maritime transmitter, and very limited ship transmissions. For the signals I do receive I can tell what they are saying but the signals are generally weak and noisy. I am not expecting too much based on my location and installation limitations but I would like to see if I can clean up the signals I do receive and possibly get some more.
I am considering my options to try to improve reception. Ideas:
- Increase gain of yagi by 2-3 dB
- Add preamp and possibly FM trap at antenna. I’ve never worked with these before.
- Lower loss coax - Running new coax is a pain so I would like to avoid it if possible. Also, I cannot easily run larger than ~0.25” diameter given the routing needed.
- Anything else?
I am seeking advice for my situation and for prioritizing what to try next. Thank you.