Don,
There are plenty of well designed dual frequency Yagi's in the 800 and 1900 cellualar bands. It is also fairly easy to make a Yagi in this band--but considering that you can buy one for $60 I would just buy one. (and love the 12 dB gain-and directionality).
It is rare to use the WiFi when under way--just too many issues. But in many marinas, the WiFi signal is weak and a directional antenna is an excellent device to have to increase the gain. Another option is an omni directional antenna with the amp built in at the base, and USB as a conductor. This helps with the signal loss due to coax.
Yes, I am well aware of the pattern of radiation at 800 and 1900 GHz from verticals. The issue here was feedback between the antennas reported, even in a metal van, so there was considerable amount of signal getting to the interior antenna (and phone or MiFi reciever) from the external antenna. Because of the radiation pattern, you would not expect this, yet it is reported. My point is not that you wouldn't find a null at the ends, but that the radials would block the signal. I may well be wrong and will try and see if I can measure a null under the radials, and compare it with that null at the apex of the antenna.
I would not use a pot--a small sheet of aluminum or foil would give as good an effect and not be as much of a problem to store. We probably won't use the cellular antenna on the boat for a few months, so I am not experimenting with that.
We do have an amplified (amp built in the base of the antenna) for WiFi--when we are in campgrounds or marinas and the signal is weak. With this there is no issue of feedback, because of the direct connection to the computer.
There are plenty of well designed dual frequency Yagi's in the 800 and 1900 cellualar bands. It is also fairly easy to make a Yagi in this band--but considering that you can buy one for $60 I would just buy one. (and love the 12 dB gain-and directionality).
It is rare to use the WiFi when under way--just too many issues. But in many marinas, the WiFi signal is weak and a directional antenna is an excellent device to have to increase the gain. Another option is an omni directional antenna with the amp built in at the base, and USB as a conductor. This helps with the signal loss due to coax.
Yes, I am well aware of the pattern of radiation at 800 and 1900 GHz from verticals. The issue here was feedback between the antennas reported, even in a metal van, so there was considerable amount of signal getting to the interior antenna (and phone or MiFi reciever) from the external antenna. Because of the radiation pattern, you would not expect this, yet it is reported. My point is not that you wouldn't find a null at the ends, but that the radials would block the signal. I may well be wrong and will try and see if I can measure a null under the radials, and compare it with that null at the apex of the antenna.
I would not use a pot--a small sheet of aluminum or foil would give as good an effect and not be as much of a problem to store. We probably won't use the cellular antenna on the boat for a few months, so I am not experimenting with that.
We do have an amplified (amp built in the base of the antenna) for WiFi--when we are in campgrounds or marinas and the signal is weak. With this there is no issue of feedback, because of the direct connection to the computer.