Is there any advantage of a DC grounded base load over a 1/4 ground plane for mobile use? I read the DC grounded base is good if lack of ground plane, I would like to learn more about them. Sorry if this has been covered I have searched several times but would like some more knowledge on the subject.
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DC Grounded Base Load Antenna vs 1/4 Ground Plane mobile antenna
- Thread starter jr26
- Start date
BJ radionut
Supporting Member and 6m addict
Yes exactly primarily for mobile installation. Like to compare 1/4 top load like firestick, middle load like HQ27 to something like Laird C27, PCTEL MLB2700. Larsen NMO27. Mostly what I find on the subject is for base antennas, I do understand they share a lot of similarities.
BJ radionut
Supporting Member and 6m addict
(Almost) every radio have resistor on antenna input that makes any antenna be DC grounded.
You can add resistor to GP antenna if you wish. 100kOhm 2W will work easily up to 1kW.
Mike
You can add resistor to GP antenna if you wish. 100kOhm 2W will work easily up to 1kW.
Mike
Ok Thank you I think I am getting DC grounded at base confused with DC grounded. From what I understand Browning Br140 has shut in them not sure about the others. I currently run a Browning Br140 on a small car I may try a PCTEL or larsen 30-34 mhz coil with longer whip. Also wondering if this would work better on the fender mount of my pickup replacing a Hustler Hq27.
The Browning is a copy of the Maxrd/Pctel. The higher freq coil and longer whip is a headache and little benefit. I have tried every coil you mentioned and best result with shunt fed 26-30 MHz coil with long whip, like Wilson 1000 style antenna.
I think you just pointed out the main difference there, wavelength.
The 5/8 will have more radiation resistance than the 1/4. Instead of 36Ω typical of 1/4 antennas, it could be closer to 45Ω for the 5/8 if I go by the ideal charts in the ARRL antenna book. There is also a point between 1/4 and 5/8 that would have the same radiation resistance as the 5/8, somewhere around 100°, but it would require a series capacitor to tune it and that would isolate the antenna from DC ground even with the resistor in the radio, so the 5/8 is better because it can be tuned without cutting off the DC ground and because of the ease of shunt tuning using a tapped inductor..
I think another difference is in the pattern. The 5/8 will have a pattern closer to the horizon compared to the 1/4 where a good portion of the signal goes off at higher takeoff angles into shorter distance skip land that the ionosphere may not be capable of refracting back down. For local, I would definitely go with a 5/8.
So it sounds like next to impossible to have a 64" shunt fed with NMO mount. My Choices are 30-34mhz end fed with 64" whip PIA to tune, little benefit and more noise, BR140 shorter lower quality, PCTEL MLBDC 2700 slightly better than BR140, change nmo to uhf for a wilson 1000, or search ebay for a Laird CW27.
Ahh, yea at 11m, 5/8 is huge. Not sure what I was smoking there. You sure can shunt feed a 64" whip. Would work good, I think thats about how long mine is