7

A random longwire is just that, a random length. There is no optimum length, by definition. Usually people use random longwires for multi-band operation. Since the design frequency is "a lot of them", the strategy of a random longwire is more or less to give up on making the wire suit any particular frequency, and just deal with the mismatch with a ...


4

First you don't necessarily have to do anything. The SWR is below 3 for the bands and most transceivers can handle that OK. If you want to try to get the resonate points inside the bands you will need to lengthen the wire. it is usually a good idea to start with too much wire and trim the length to bring the resonance down, but in your case it look like the ...


3

A random long wire is just that, random. While large loops at the end or bending the wire might change the resonant frequency, a random wire isn't (unless by chance) resonant anyway. So loops and bends just make a different random wire antenna which is neither better nor worse. The shape of the antenna isn't going to affect efficiency directly. Think about ...


2

If at all possible, the feed line should go through a panel that is connected by a short cable, or directly connected, to a ground rod. A lightning arrester is a good idea also. All earth grounds should be connected, including the ground rod connected to the service panel, the ground rod connected to the coax shield, and your station ground. In the US, ...


2

The radiation pattern of an antenna laying on the ground can be easily approximated for the transmit case: it's roughly equivalent to a dummy load. Unless of course you are in Antarcitca: ice is transparent enough to HF that it's basically invisible. But I don't think there are any retirement centers in Antarctica. For a receive application, you might hear ...


1

First, what bands are you listening to? You should hear activity on roughly 20m – 40m during the day (and 15m sometimes), and 40m – 160m at night. This is close to the bottom of the sunspot cycle, so signals are often fairly weak, but there should be a few loud stations on 20m and 40m. Your antenna would do better to be higher, but it's high enough for ...


1

It's not clear to me from your question, so I'll mention here that best practice is to end your antenna with an insulator and attach the insulator via rope or whatever to your tree or building. And yes, the length of the antenna includes that loop of wire around the insulator. [image credit: DX Engineering] HOWEVER, it's not unusual for a testing setup (or ...


1

I keep seeing claims that a properly constructed dipole will be close enough to 50 ohms that a balun is not needed. The necessity for a balun has nothing to do with how close the feedpoint impedance is to 50 ohms. Rather, a balun is required because a dipole does not have equal impedance from each half to the coax shield. Consequently, the current will not ...


1

a 49:1 transformer with a bit of capacitance will help you more. for a 9:1 UNUN its better to choose a "random length". Like: 29 35.5 41 58 71 84 107 119 148 all in feet!


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