07.19.20

Covert Antenna Placement In Residential Radio Communications Stations or Listening Posts #sigint #comint #diy

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You can also get a look at the history of Cybertek and read some of the earlier issues at http://67.225.133.110/~gbpprorg/2600/TAP/cybertek/index.html. I don’t run that site, and the guy that did is an idiot despite his high technical skill level, but it’s still nice to see someone decided to put it all online. All of that material is now public domain. Copy, fold, spindle, mutilate, make derivatives, write fanfic, set up a mirror, have fun, enjoy!

The site was hosted by Joe Loritz/GBPPR who I have no connection with, and with whom I disagree with sociopolitically. Considering his legal issues, it won’t be up forever and I’m surprised this mirror still exists. Anyway, please do what you will with it, and tell me about any derivatives which I’ll then promote and mention on cybertekzine.com.


In a previous post, I mentioned how good intelligence collection and analysis can help you with ferreting out deceptive information whether it’s from some some troll living in his friend’s basement, or a professional operation setting up a honeypot, perhaps in the hopes of catching a bunch of a particular special interest group with something like an IMSI catcher. To that end, links to a couple of nice intelligence and counterintelligence manuals from archive.org were posted up.

One of the nicer means of collecting information to be turned into intelligence is communications monitoring. The discipline is broadly known as Signals Intelligence (SIGINT), and for our purposes we concentrate on a subset of SIGINT known as COMINT or Communications Intelligence. COMINT can help confirm or deny a lot of data you come across on the internet.

DIY hobbyist COMINT has been a thing since the 1990s, and there is a plethoria of information out there. I first wrote about it in 1991, and have since written many subsequent articles. This article puts a more covert, security-oriented spin on things.

In the United States, it is currently legal to monitor non-broadcast radio communications as long as they are not encrypted. Other countries are less fortunate in this regard. However, even in this country you might decide to enhance your level of discretion.

In this picture, there are two antennas on the roof of this house. The lower one is a VHF vertical dipole element often used for land mobile radio stations. When mounted on a mast like this, it is broadly directional in the direction the antenna is pointing. The antenna on top is a 2 Meter Amateur Radio horizontal loop used in VHF weak signal (SSB/CW as opposed to FM) operations. It is obvious looking at this installation that the resident is a ham radio operator with more than a casual interest in VHF operation. A discone antenna would present a different appearance and send a different message to an observer, as they are often used by individuals engaged in communications monitoring due to their broadband non-directional characteristics. In certain situations this level of advertising may not be optimal for some people. More realistically speaking, mounting a mast on the roof with antennas is a bit of an undertaking some may not be quite up to accomplishing yet (if at all).

Here is the same antenna mounted in an attic. To simulate a mast and put the signal lobe in the desired direction, it was mounted on a piece of scrap 1/2″ copper pipe. Functionality is not seriously compromised compared to a rooftop installation. From a security standpoint, there is no external indication of a communications station in the structure, and also no way an observer can determine the frequency band in use by estimating the length of the antenna.

Lest anyone think that using antennas is anything new, here is an example on HF (Shortwave) from the communications chapter of the old US Army Special Forces Field Manual. It’s just easier to do on VHF and UHF.

From a communications monitoring standpoint, you might have multiple receivers to hook up to a single antenna. In that case, you will need a signal splitter. Consumer grade TV splitters will work fine. You just need adapters to go from the F connector to whatever your receiver uses. You may also come across an LMR grade splitter. This one splits the input into four outputs. It’s spec’d for VHF high-band, but works fine elsewhere in the bands too.

By getting a proper antenna in your attic, you’ll see increased signal gain from the added elevation and noise reduction from getting away from all those consumer electronic devices on the same floor as you. You can also enjoy the fact of having a super secret squirrel listening post that your neighbors and random people passing by are unaware of. Extra style points if you have a Brill Lyle lab tucked away in a closet.

Mucho bonus points if you have one of these in there.

https://watkins-johnson.terryo.org/