Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who shares the following guest post:
Recently we had a remodeling job performed at the home QTH and the workers used telescoping poles to form a dust barrier. When the job ended, they said I could have the telescoping poles, a product called ZIPWALL10, which when collapsed are four feet long but extend to ten feet. This got me pondering about how handy these could be in the radio shack, especially for indoor impromptu antennas.
Close up of the ZIPWALL telescopic pole.
Indoor antennas, especially wire antennas usually have to be secured to a wall somehow, and should be as high as possible in the room. That requires using adhesive tape to attach the wire and a ladder (most ceilings are eight feet), but using the ZIPWALL10 poles it’s easier and safer. Below is a temporary random wire antenna in my shack using 26 gauge insulated wire strung between the two poles.
Random wire in shack room is a bit hard to see but it is strung between the two poles.
What’s nice about these poles is they have rubber feet to grip the floor and plastic pads on top to avoid damage to the ceiling. The top section is spring loaded to assure a tight fit. The ZIPWALL10 model extends to ten feet in three telescopic sections. No tools are needed to set these up, and they conveniently collapse for storage.
ZIPWALL10 pair along with roll of 26 gauge wire for temporary indoor antenna installation.
These poles just happened my way due to a remodeling job, but surely other types are available on the market for those wanting to experiment with indoor antennas. The price for a ZIPWALL10 pair on Amazon is around eighty dollars. Thanks for reading.
What a great use for ZipWall poles, Mario! I’ve spent the past few days at an ocean front condo and could have used two of those supports to suspend a small, lightweight passive loop antenna safely on the balcony. That’s fantastic your contractors simply gave you those poles!
Thanks for the tip!
As you mention, Amazon sells a full line of ZipWall options (links below support the SWLing Post) but these can also be found at most home improvement stores.
The new balun has the same schematic as the previous one:
But it is slightly bigger, has a better connector for the antenna wires and (according to NooElec) uses a transformer which allows the tiny balun to work more efficiently from 0 to around 70 MHz (check out the charts found in the downloads section of this link).
The transformer used, judging from the pics, is a CoilCraft WB9-1, whose data can be found here:
As I wrote the reason for this was the fact that a friend of mine reported that he used the (v1) balun with a Loop On Ground (LoG) Antenna !
If you look at the schematic (above) you’ll notice that there’s a “jumper” labeled R1 (zero Ohm resistor). That tiny detail is important, see, leaving the balun as is, it will work fine with a longwire, one just connects contact #1 to the antenna and #2 to a counterpoise or ground system and there he goes, BUT there’s another way to use the balun, that is, CUT the “jumper” (ok, resistor) labeled “R1”. If you cut it, the balun will become a 9:1 isolation transformer and with such a modification will work just fine with the KK5JY “LoG”
According to what my friend reported, the balun works just fine, and although probably the ferrite core used in the V1 isn’t up to par with the original one used by KK5JY, the difference isn’t so huge.
Oh, and I also suspect that the modified balun may work fine with the KK5JY simpler passive loop http://www.kk5jy.net/rx-loop/ which may be a nice antenna for restricted spaces!
I think it may be of interest to people not knowing/willing to wind their own baluns, at that point one may just need an enclosure to protect the balun and putting up a receive antenna will be as easy as 1-2-3.
Thank you for sharing this! Readers: Grayhat has been encouraging me to deploy a LoG antenna at my home and I do plan to do so in the coming months. Please comment if you use a LoG similar to the KK5JY model and what your results have been.
Many thanks to SWLing Post contributor, Marty, who shares this fascinating article from the IEEE Spectrum:
A new antenna that uses saltwater and plastic instead of metal to shape radio signals could make it easier to build networks that use VHF and UHF signals.
Being able to focus the energy of a radio signal towards a given receiver means you can increase the range and efficiency of transmissions. If you know the location of the receiver, and are sure that it’s going to stay put, you can simply use an antenna that is shaped to emit energy mostly in one direction and point it. But if the receiver’s location is uncertain, or if it’s moving, or if you’d like to switch to a different receiver, then things get tricky. In this case, engineers often fall back on a technique called beam-steering or beamforming, and doing it at at a large scale is one of the key underlying mechanisms behind the rollout of 5G networks.
Beam-steering lets you adjust the focus of antenna without having to move it around to point in different directions. It involves adjusting the relative phases of a set of radio waves at the antenna: these waves interfere constructively and destructively, cancelling out in unwanted directions and reinforcing the signal in the direction you want to send it. Different beam patterns, or states, are also possible—for example, you might want a broader beam if you are sending the same signal to multiple receivers in a given direction, or a tighter beam if you are talking to just one.[…]
Thanks for sharing this, Balázs. The video actually makes a good point: it takes so little to make an effective FM antenna to receive local stations. I’ve been with repair technicians when working on radios They’ll often use their precision screwdriver as an antenna to test the receiver before reassembly.
I also carry a couple cheap instrumentation patch cord with alligator clips on both ends to act as a short antenna or antenna extension when needed. Honestly, It’s amazing how often I reach for them!
Many thanks to SWLing Post contributor, TomL, who shares the following guest post:
Summer Daytime DXing 2019
I took note of the mediocre band conditions this summer amongst amateur radio operators as they were making off the cuff comments about still being in a solar minimum. Some had gone out and bought upgraded transmitters to solve the problem (MOAR WATTS!). And more power thrown at a weak ionosphere does seem to help get a signal farther. I had not been out since the spring and decided to find out for myself. But instead of more watts, I wanted more height.
Greene Valley Scenic Overlook is open to the public from May through October on weekends only (and only from 11am-6pm). It was the largest land fill (aka, garbage dump) in Illinois, now covered over and producing captured methane gas. On August 3 & 4, I ventured over there to see if its 190 feet above the surroundings might help my radio reception.
After trying my luck with a 12 foot vertical antenna on a tripod (and numerous children running around it chasing butterflies or looking at the view of Chicago), I went out the next day and parked away from anyone and put up my 19 foot vertical on the roof of the car. This setup is still amazing to me and works much better than the tripod mounted antenna, probably because it has a proper ground plane as well as being 7 foot taller.
So, yes, the conditions were so-so, not too bad and not too good. Lots of weak signals and some empty frequencies that I had expected to hear some South American stations around the 5 – 10 kw range. Weak stations from Asia were more scratchy sounding than usual even with the extra 190 feet of height. Here are 5 broadcast recordings as a sample (times in UTC):
Running out of things to listen to, I wandered over to the 20 meter amateur radio band and found a different situation. Propagation was decent between the Western hemisphere and Europe. Lots of “pile ups” going on with people trying to make contact with their trans-Atlantic counterparts. Some said they were running 500 watts or more, so more power does seem to help! Here are 5 recordings to show how active it was:
This outing was quite educational and I find it curious that people running 1000 watts or less are able to be heard well between continents but the large broadcasters were difficult to hear. Antennas pointed in the right direction, at the right time of day and frequency, can certainly do amazing things, plucking those weak signals out of the air so easily. And I do think the extra height had something to do with hearing this magic, too!
An easy way to lookup amateur radio operator “call signs” is to go to web site QRZCQ.com which does not need a login. Some records may be out of date, but most of it is accurate.
Setup used was a cheap Dell laptop, Windows 10, SDR Console 3.03, connected to the AirSpy HF+, a Palstar amplified preselector, and an old Kiwa BCB filter, then going up to the car roof magnetic balun (a Palomar MLB2) which is then connected to the 4 magnet base and the MFJ 19 foot stainless steel antenna. You can read about it here:
Brilliant report, Tom! It’s true: the bands are fickle, but like you I always find interesting things to hear on HF. I think your setup using your vehicle as the ground plane for the antenna is a fantastic idea. Plus, set up is easy, self-supporting, and you’ll never have to worry about a park ranger, for example, complaining because you have a wire suspended from a tree. And when there are no trees? You’re still golden.
Thanks for sharing your experience and DX! Amazing that even with mediocre conditions, you still snagged some distant signals.
Published on: 2018/11/20, Rev. 1.0 July 2018, Rev. 1.1 Nov 2018
Author: Chavdar Levkov LZ1AQ
Two identical small loops were placed one above the other according to Fig.1. One of the loops is very low – almost on the ground. The other one is placed at height which usually is used by the loop users. Two AAA-1C wideband active antenna amplifiers were used. Their gain difference was not more than 0.3 dB. The feeder was FTP cable each 20 m long. No cable baluns were used. The outputs were connected through two way antenna switch to a SD RX (Perseus). I used a measurement technique described in – A Periodic Switching Technique to Compare Receiving Antenna Performance in the Presence of Strong Fading. This is a precise method to compare two receiving antennas with real sky wave signals and the resolution can be less than a decibel. The idea is to switch periodically between two antennas and to estimate their difference on a calibrated graphic strength meter of a SD radio.[…]