Hi Guys!
I see that the antenna questions are still here in my favorite listening forum. I have some suggestions for you guys to try on inexpensive receiving antennas.
Since you are not transmitting, the sky is pretty much the limit on what you can do. You don't need to be
as concerened with formalities such as resonance/reactance and SWR etc etc etc.
Some suggested reading would be websites such as DXzone and other Shortwave Listening websites. If you want to build an antenna and really want to know something about them, read
W4RNL's antenna website.
Or you can just build yourself a wire loop or hoop.
Loops are vertical (like the signals most of you want to hear) in nature and the loop opening points to the two directions that it is the strongest in receiving ability. Loops are bi-directional so you may need to be able to rotate the loop if your stations you want to hear aren't all comming from the same location. A one wavelenght loop for 155mHz is about 72" (18" per side time 4). A couple of sticks, tubes, fishing poles, pvc pipe, bamboo or whatever connected in the center and making an "X" or cross to act as spreaders will keep your loop open. The lighter, generally the better. Run some wire around your support and connect your coax on the bottom of the loop. Connect one end of the wire to the center conductor and the other end to the sheild of your coax. There should be a small gap (about the width neccesary for the coax connections) at the bootom where you are making the connection. Place you loop on a pole or stick or in a tree with the opening pointed to what you want to hear and you have an antenna for receiving.
Height, within reason, and the higher the better is still a general and pretty good rule of thumb.
Hoops are horizontal loops. Hoops need to be at least one wavelength in perimeter, however the more wavelengths you go the better your hoop is going to attract signals. Hoops are not directional and are generally more quite than any other antenna. However the quieting may also impede your listening as the signals most of you are trying to receive are vertical in nature. But compared to a rubber duck or indoor antenna, I'm fairly certain you will hear more with an outside hoop. The beauty of the hoop is that (providing your house isn't made of metal or you don't have metal gutters) you can run a small hunk of coax out your window and connect it like the loop above and run the wire hoop around the eaves of your house. Not only is your antenna hidden but because most homes are larger than one wavelength for 155 mHz, you will have a huge aperature (signal capture area) in which to attract signals and your neighbors won't even know you have an antenna. Hoops preffer more height than the loop but even at the height of typical house eaves should give you some pretty good performance. There is no reason why your hoop couldn't be connected to a small hunk of coax (just enough to get outside) and have your wire hoop run from the house, up to the tree across the yard, around the property back down to the house and finally connected under the eaves at your coax.
And finally just a basic straight run of wire. This is something a lot of SWL listeners do when out doors. Drop an end of your coax to the ground. Ground the sheild side of the coax. A tent stake in the ground is generally adequate. Take the center conductor and connect it to a wire and run it out for as long as you can. I have heard of lenghts approaching MILES. This will trap signals in the direction of the long wire run. This is very directional but requires no supports as most just lay the sheilded long run of wire on the ground.
So there you guys have some ideas to play with. With a small hunk of coax and no connector on one end, connected to any stranded, sheilded wire (gauge is not critical) and you can experiment with different antennas.
Have fun!
Note the above is not designed to be a end-all for what you can do, but hopefully get you building your own antennas, doing some experimenting and get the bug to want to learn more on how antennas work.
Hoops and Loops - Just plain old wire
Well, Yes - and some very interesting technical articles in both that group and the Shortwave antennas group as well. Stop by - you might learn something. I know I did.
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