Attic Antenna Recommendations for Train Telemetry and Defect Detectors

[PoorInRichfield]

I'm looking to purchase two antennas and mount them in the unfinished attic (indoors) of my garage:

1. One antenna tuned to the ~160 Mhz range to listen for a defect detector that is a few miles from my house.
2. One antenna tuned to the ~455 Mhz range to pick-up train telemetry signals (HOT/EOT/DPU)

Additional requirements / info:

• Both antennas will be connected to their own individual software defined radios (SDR).
• Both antennas will be used for receiving-only (I think that makes them "Rx"?)
• I can already receive the desired defect detector using the cheap dipole antenna that comes with the RTL-SDR Blog V4 SDR kit, but it's very staticky sounding and I'm hoping to improve on that with a better antenna.
• There is considerable room in my unfinished garage attic. It can accommodate an antenna over 8 ft tall if need-be, but only if such a tall antenna will noticably improve reception. I'll have to fabric a way to mount the antennas no matter what I buy, although having a mount that screws into wood is likely what I need (versus a pole in the ground if I was looking for an outdoor antenna).
• I'm not opposed to alternate solutions such as a single, dual-band antenna and a duplexer to split the antenna feed into UHF and VHF (This is assuming my understanding of what a duplexer does and assuming there is such a thing as a dual-band antenna that would fit my needs.)
• I would like to purchase a ready-tuned antenna versus making my own.

I know very (VERY) little about antennas and have found that finding the right one is very confusing as I don't understanding all the terminology... please word your responses accordingly (I.e., explain things to me like I'm 5 years old-ish. )

I'm considering purchasing the following two antennas but am looking for advice from those of you with more experience as to whether there are better and possibly less expensive options.)

1. DPD Productions EOTD Indoor Blade Antenna ($90) for hotbox alert detection
2. DPD Productions TrainTenna Blade Indoor Antenna ($120) for train telemetry detection

Thank you in-advance for your suggestions and input.

 

[mmckenna]

I think the DPD antennas are extremely overpriced.

Longer antenna usually means more gain. More gain means it is going to get more signal to the coax, which should improve reception.

Since these antennas will be indoors, you don't need to go overboard.

If it was me, I'd mount a pair of mobile antennas up there on a ground plane. The ground plane can be as simple as some metal screen, chicken wire, or sheet metal. You can even use some scrap wire.
The DPD TrainTenna indoor is 1/2 wave, and has no ground plane, so it's going to be 0dB. You can get higher gain mobile antennas that will outperform that easily, and much cheaper.
This antenna:
EM Wave EM-M10004-LS VHF 132-174 MHz Tunable 3dB gain Mobile Antenna - NMO

On this mount:
Larsen NMOKHFUDSMAFI - NMO 3/4" Hole Mounts SMA
That has 17 feet of cable with an SMA connector on the end that may match your SDR.

Add another mount with a suitable UHF antenna for the EOTD:

EM Wave EM-M10007-LS UHF 420-470 MHz Tunable 5dB Mobile Antenna

EM Wave EM-M10007-LS UHF 420-470 MHz Tunable 5dB Mobile Antenna

theantennafarm.com

Nice thing about the NMO mounts is that you can swap out antennas if your needs change.

 

[ratboy]

I would pass on the EMWave antennas and just go with either mobile antennas as mmckenna suggests, or since you have room, make yourself a pair of ground planes. Very easy, and you can hang them as close to the attic ceiling as possible, for better reception. I've been listening to rail for like 50+ years, and for the life of me, I don't really understand why you would waste (IMHO) the resources (SDR and antenna) to listen for EOTD's. It's not like they talk or anything. I just don't get it. So you hear when a train is close? I used to put it in my scanners a long time ago, and the squawks did nothing to enhance my listening experience. But it's your money. Maybe because I live near the NS Chicago Line, and trains are constant, I'm spoiled?

 

[PoorInRichfield]

Longer antenna usually means more gain. More gain means it is going to get more signal to the coax, which should improve reception.

Ah, that explains the mystery of antenna gains. I was unaware of why some antennas promised a gain boost while others do not... until now. I thought it was black magic . I agree that a regular whip antenna should suffice whereas antennas like DPD Productions antennas seem to command a premium as they are meant to look somewhat appealing in an indoor setting... which doesn't matter to me. I have to do some research into "ground plane" which was something I was completely unaware of.

I don't really understand why you would waste (IMHO) the resources (SDR and antenna) to listen for EOTD's.

A little off-topic, but I have reasons. I like railroad photography and videography, but don't have the time (or interest) to sit trackside all day and hope a train comes. I prefer to get setup trackside a few minutes before the train arrives, get my shot, then move-on with my day. I happen to live a block from two different rail lines, so I don't need a lot of heads-up to get trackside.

As of the time I'm posting this, I really don't care about capturing any radio communications because I use ATCS Monitor. However, ATCS Monitor users know it's going the way of the dinosaur this year. The railroad subdivision to the north and to the south of my location have both "gone dark" within the last month and it's only a matter of time before I'll need a "Plan B" to assist in knowing the locations of trains.

The first part of my "Plan B" is to listen for the defect detector alerts located to the north and south of my home as a 15 to 25 minute "heads-up" warning. Both detectors announce the train's direction and since I know where both detectors are located, I know I have about 15 to 25 minutes to get trackside, provided the train don't stop. The website DefectDetector.net is a great resource if one wants to know if there is a defect detector nearby and what information it's alert provides.

The second part of my "Plan B" is to detect the train telemetry "chirps" as a ~5 minute warning. Since the defect detectors already notify me that a train is potentially coming towards me, the telemetry info helps me to know that the train is getting very close and now I only have about 5 minutes to get trackside... or perhaps just watch the train go by from a distance. I've already seen that monitoring train telemetry can give "false positives", especially when one of the railroads near me is a regional railroad that has no audible defect detectors in the area, but for the most part, I think it's worth detecting the train telemetry when ATCS Monitor goes dark.

I have more reasons for wanting to detect both defect detector alerts and train telemetry for other projects that are more inline with designing an ATCS-like alternative, but that's a story for a different day.