Recent content by The DB

According to This coax loss calculator, a 150 foot run of RG8x with a 1:1 match on the antenna end, 100 watts in will get you 58.498 watts absorbed by the antenna. There is 2.32 dB of loss, all of it from the initial pass through the coax. According to the same calculator, a 150 foot run of 450...

The short and quick answer is, some people notice a difference after installing said ground plane kit while others don't. Now for a slightly longer explanation... The ground plane kit, in and of itself, won't improve performance enough to be noticed. For that to happen you must have a problem...

Is it something like 2 meter and 70 cm ham bands where the frequencies in question are harmonically related (or at least close)? Is there some form of matching on the antenna? Is there some form of inductive/capacitive loading on the antenna? How did they achieve said multi-banding? Although...

This is the specific text he has highlighted. When you add a capacity hat to a 1/4 wavelength antenna element, efficiency goes down. This is a form of loading and all forms of loading have this effect. But this is also that "less efficient" statement that so many people get hung up on, when...

Inductance and capacitance have the effect of changing phase. It is literally their only job when it comes to antennas. This effect, however, has a wide range of uses, from shortening 1/4 wavelength antennas (possibly the most common use) to antenna matching. Changing the phase in this...

I'm surprised I didn't post anything about this back then, I must have been busy when this conversation was happening... I agree, the a99 is not a 1/2 wave over 1/4 wave. That came from advertising for said antenna, which is apparently enough to get some people to believe it regardless of any...

It wasn't the DDRR that I was analyzing the vertical polarization models show, it was the Super Sinner, and later a dipole antenna mounted horizontally in the modeling software. The DDRR will definitely have a vertical component. The DB

First things first, I wouldn't get hung up on the magnetism of the loading coil. It is a thing, but not something we are typically concerned about. A step in the right direction would be their inductance, but that is really only half way there. What we are really concerned about is the...

Did you calibrate out the coax before taking these measurements? Doing so would eliminate the coax from your possibilities. To do so you need to put your calibration loads on the far end of the coax and recalibrate the device with the coax attached. It may take one or two additional adapters...

How big is the change on the field strength meter? How many radials did you use with that antenna? Were they horizontal or angled down? A field strength meter will be far more sensitive than, say, an s-meter. Used properly, most can pick up on changes that are very small, well below the...

VNA stands for "Vector Network Analyzer", think of it like an advanced antenna analyzer. Most tend to be pretty pricey but you can get a nanoVNA for around $50 or $60 these days, which is amazing based on what antenna analyzers cost not to long ago (and really still even today). If you already...

Wow, you dug these out from the past, even a post from Doc's account which I haven't seen post in a decade or more... Hope hes doing well. Its good to see people still go back and read said posts, a lot of good information in this forums history... What I was talking about has nothing to do...

I know the capacitor in the K40 is 130 pF. I don't know anyone wo had taken the K30 apart and haven't found any info on said capacitor online so I am not sure about that one. Likely to get that information, you will have to have someone take apart a perfectly good K30... The DB

For any length of antenna shorter than 1/4 wavelength, there is a loading coil that will, by itself, get you resonance. However, when you start shortening antennas to this degree, just because you are at resonance does not mean the SWR will also be at a use-able level. Because of this...

Is it possible that this is the case? Yes. So the next questions becomes... How large of a roof would it take for something like this to happen? And then... Are their any vehicles that are actually that large? The smallest size would this would be possible would be be a roof that is larger...