Blair, Even if the resonant Z was under 50 ohms, adding reactance of either sign will still increase the SWR. If you have the TLW program from the ARRL Antenna Book, you can put in test values to see
Blair is right that a 40+j10 ohm load has an impedance magnitude is 41.23 ohms, but it has a vector angle of 14 degrees. The SWR is only the simple ratio of the impedances when the vector angle is 0
Michael, You've probably gotten lots of comments on this, but I'll throw in mine, too. As far as the balun vs. unun issue, it probably doesn't matter too much. You're right that both the antenna and
Perhaps there is a question of semantics to say that a 0.08 wavelength vertical, which has about a 2.5 ohm radiation resistance, qualifies as a "fairly good" antenna on 160m? With a 5 ohm ground syst
Joe, I have used a Force12 flagpole vertical for several years now, which has HOA approval. The stock F12 flagpole is 16 feet of 2" diameter aluminum, painted white, but I got it with 3 extra section
Whether you short a nearby 2 wl quad element or leave it open, it will still be resonant and carry a fair amount of current. I think the benefit of shorting the element is that the currents are symme
Jim, My models show that a 2 wl square loop will have a feed Z of around 270-300 ohms. This is the case for a single loop and also for a concentric loop around a 1 wl loop with both fed in phase from
Isn't it about time to split off an "All Inverted L's, All the Time", e-mail group? Same questions, same 100 answers each as the last 100 times. 73, Terry N6RY _______________________________________
This is a great article on dealing with practical problems in measurement and matching. Thanks for making it available, Jay. The use of a hairpin match is, by far, my favorite method of matching impe
It would appear that the SWR curve that is still on the Array Solutions web site was measured with a misapplied 4:1 voltage balun (which puts half of the antenna RF voltage on the outside of the coax
A cage dipole has essentially the same gain (and pattern) as a regular dipole. The bandwidth increase is real, but those claims of 5 dBd gain are totally bogus. 73, Terry N6RY _______________________
I think one reason that hams would rather put the phasing network close to the antenna elements is that the pattern bandwidth is almost always better the closer these networks are to the antenna elem
The phasing section of this document has been around since the 1960's, if not before. It was developed long before most hams found out about the interesting effects of mutual coupling on the feed imp
I don't have any personal data to validate this, but W8JI, N6BT and others have claimed that verticals with modest numbers of low elevated radials have increased losses when there is also a path to e
This is a nice antenna with a direct match to 50 ohms. Using AL7KK's dimensions and bare #12 copper wire, an EZNEC model shows 0.44 dBi gain at 19.5 degrees above the horizon over "average" ground. T
John, The configuration with the director generally has better performance, but only at closer spacings. Unfortunately, the trade-off with close spacing is lower feed Z and a similarly reduced bandwi
Larry, The high current point will be very close to 1/4 wl from the open end of the inverted L, for any configuration whose length exceeds 1/4 wl. However, although increasing the length of an invert
I can see what Jerry K4SAV is talking about. Using a 45 foot vertical wire and four 65 foot hat wires indicated by EI7BA, resonance is around 2.36 MHz in my EZNEC model. This varies somewhat dependin
As Wes N5WA pointed out, coupling to your tower could be a real issue. It sounds like the height of your tower, plus the capacitive loading of the 40m yagi, could make it resonant near 160m. With fur
Blair, You've gotten some good inputs on your question. Vertical polarization is definitely the way to go on 160m. Given your space constraints, the K2KQ "Double-L", would be a good antenna for you.