2016-12-12
Antennas
Check Ins: 10 Total
On tonight's net, we first discussed follow up questions from the previous net about repeaters.
- Linked Repeater Systems:
- How do they work? The short answer for that was that each linked repeater has a seperate set of radios that operate in a different band, often in the 220Mhz band. Here's a graphic from the Dixie Amateur Radio Club in St. George, Utah that describes their linked repeaters. Most linked systems work much in the same way. http://www.dixieham.org/forms/DARC-Repeater-System.pdf. You can also refer to the GMRA (www.gmra.org) or Colorado Connection (www.colcon.org) for information about local linked systems. Additionally, IRLP and Allstar are methods to link repeaters around the world via the internet. We will definitely cover those systems in a future net!
We then moved on to antennas:
- Vehicle Mounted Antennas: Which is the best?
- Mike (KE0KDI) talked about his antenna which he built directly into his truck.
- Terry (KE0HNW) talked about mag mount antennas.
- Mike, Terry and Al (WA4HND) all agreed that mounting the antenna in the center of the vehicle is most ideal. Al also mentioned that doing it Mike's way is good to get the best ground plane propagation, because the car's roof can act directly as RF ground for the antenna. All agreed that a magnetic mounted antenna is better than a trunk mounted antenna (Ground plane) or just the rubber duckie antenna (Gets the antenna outside of the vehicle).
- Base antennas:
- Several suggestions were offered for a base mounted antenna at one's house. Among them is the following:
- J-Pole
- 1/2 wave with radials
- Both Mike and Al noted that grounding is important to the successful use of the antenna.
- Several suggestions were offered for a base mounted antenna at one's house. Among them is the following:
- Grounding
- Proper Grounding
- RF vs Electrical Grounding
- PolyPhasers
- There was a lot discussed about grounding, which Al mentioned, is better suited for a classroom setting.
- HF Antennas
- Dipole vs Yagi
- G5RV Junior Dipole
- Dipole: Half of antenna is radiator and half is counterpoise or RF Ground
- End Fed and Random Wire
- Dipole vs Yagi
- Feed Line
- LMR 400 Low Loss Coax
- Ladder Line
Additional Links:
- https://youtu.be/HkmD3Sgz7Q0 - Instructions on building an inexpensive 2 meter base antenna.
- http://www.kk4ice.com/?page_id=20 - Homebrew J-Pole for 2m/70cm
- http://www.hamuniverse.com/jpole.html - More J-Pole info
- http://www.arrl.org/files/file/ETP/The%20tape%20measure%20antenna.pdf - Tape Measure Yagi
- http://theleggios.net/wb2hol/projects/rdf/tape_bm.htm - Tape Measure Yagi Build
- http://nt1k.com/blog/2012/vhf-3el-tape-measure-yagi/ - Another Tape Measure Yagi site
- http://www.n9tax.com/slim%20jim%20info.html - Homebrew SlimJim antenna
- http://www.ws6x.com/ant_calc.htm - HF Antenna Length Formula/Calculator
- Of course you can google these topics and find a plethora of information!