20 October 2009

wire antennas in cramped space

Now that I have some of the best portable shortwave receivers available, I either need to upgrade my radios or my antennas in order to get more out of the broadcasts that are generously sent in my direction. I'll start by upgrading my antennas.

My small apartment makes this difficult. Indoor antennas are my only hope, and I can't run a straight wire for longer than about 20 feet diagonally along my ceiling. I finally established permanent mounts for two wire antennas that I use, which helped somewhat with nighttime reception. However, I just realized I had an asset that has remained untapped for my four years of shortwave listening: I have a box that contains approximately 800 feet of unshielded Category 5 cable. I don't need lots of ethernet cables, so I can cut a length of Cat 5, and get eight individual wires at that length which can be shortened as required.

For my first project, I want to make a five-band antenna specially designed for the NCDXF/IARU beacons. This provides me with five specific frequencies to target, and the high frequencies of the beacons require less material. I'm going to make half-wavelength elements, so the elements will be between about 18 and 35 feet long. Also, the longest element for 14100 kHz should be decent for CHU on 14670 kHz and WWV/WWVH on 15000 kHz.

But what about that 20-foot straight line limit that I mentioned? With a sharp 45-degree turn or several gentler turns, I can extend the antenna for 30 feet. I could toss the antenna up on the roof and either hope nobody notices or remove it when it's not in use. I could call my landlord and request some holes be drilled through my walls.

Or, I could ask the experts. I posted some questions about this problem on the dxing.info forums.

2 comments:

Erik said...

Have you've tried either the Sony AN LP-1 loop antenna, or its Degen/Kaito equivalent, hung at a window?

weatherall said...

Erik:
I own a Degen DE31 active loop antenna, but I don't use it much because I find the tuning selector difficult to operate. Unfortunately, I missed many opportunities to purchase the Sony active loop.