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Latest Topics

Topic Created Posts Views Last Activity
dBmicrowatts? Jul 16th, 19:51 3 71 1 week, 6 days ago
Dipole crossing vertical? May 2nd, 00:01 3 172 on 5/5/14
Ground Plane antenna near metal roof? Jul 6th 2013, 15:28 4 1,055 on 9/7/13
Does paint affect a Yagi? Jan 17th 2013, 02:40 4 706 on 25/1/13
50 or 75 ohm reference for analyzer? Jan 6th 2013, 22:52 2 669 on 7/1/13
Using ladder line with Yagi Jan 2nd 2013, 00:58 1 708 on 2/1/13
Two new ham questions about antennas Dec 9th 2012, 16:56 7 1,465 on 26/12/12

Latest Posts

Topic Author Posted On
dBmicrowatts? KO0Y 1 week, 6 days ago
Thanks so much, and for the helpful link also.
dBmicrowatts? KO0Y 2 weeks ago
I'm familiar with dBm as a measure of signal strength, where 0 dBm is 1 milliwatt. I recently cam across the term "dB╬╝." Does this mean decibel-microwatts? How can I convert this into dBm? Thanks for any help.
Dipole crossing vertical? KO0Y on 5/5/14
I'll look at that; thanks.
Dipole crossing vertical? KO0Y on 2/5/14
I have a DX Engineering vertical antenna with ground radials that works well on the higher bands, but I need a wire dipole for frequencies below 3 MHz (I'm in MARS). Would it cause coupling problems if I used the vertical to support the center feed of a wire dipole? The dipole would be at right angles to the vertical, and the twin lead that I use as feed to the tuner inside the shack would also be at right angles to the vertical. I would not use both antennas at the same time. Thanks for any advice.
Ground Plane antenna near metal roof? KO0Y on 9/7/13
Quote by W1VT

For lightning protection, you need to be aware that lightning coming in via the power lines will often seek out the shack ground--it is best if it can do so external to the house--hence the NEC requirement to bond everything together. I'd make the feedline as long as necessary to keep the ground wires straight.

Zack Lau W1VT
ARRL Senior Lab Engineer

I put the antenna on a painter's pole and stuck it out the upstairs bedroom, about 2 feet above the roof, and the SWR was around 1.1-1.3 on both VHF and UHF-better than on the deck! So I guess it will work.

About grounding: I plan to run a #8 bare copper conductor from the antenna's ground-plane side to the 8 foot copper rod that also serves to ground the HF antenna and shack (each on a separate conductor). Should I use plastic for the antenna mast or would it matter? Should I leave the roof ungrounded or should I run another #8 from the roof in a different location (straight down to the grounding rod)? The antenna ground will have two bends to reach ground: 30 then 60 degrees. Is this acceptable or should I connect the antenna to the roof and depend on the roof's straight grounding conductor? Thanks again for guidance. I want to get everything straight before I rent the 32-foot ladder needed to reach the roof peak from the surface!

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