Antenna Height Question

[dispatcher812]

So Am am looking at getting an antenna just for railroad listening. All the antennas I find for VHF are over 4 feet long 55 inches to be exact . Right now I have a 17 inch one an it receives ok. Should I get a longer one for better reception or stick with the smaller ones. This is for a mobile set up. Thanks.

 

[Ace9133uwu]

Basically anywhere between 17” & 18” is good for receiving, so your current antenna at 17.5” is the ideal receiving length for an antenna. The only things you will need are a good magmount, and RG58/U coax with the right connector for your radio. Since you’re operating a mobile setup, that’s even better because your vehicle is the groundplane for the antenna.
Height doesn’t necessarily mean much for receiving on a specific band, such as the railroad in this case.
With that said, your setup is already leaps and bounds ahead of a standard stock rubber duck.

By the way, what antenna specifically do you have & what radio are you using?

 

[dispatcher812]

Basically anywhere between 17” & 18” is good for receiving, so your current antenna at 17.5” is the ideal receiving length for an antenna. The only things you will need are a good magmount, and RG58/U coax with the right connector for your radio. Since you’re operating a mobile setup, that’s even better because your vehicle is the groundplane for the antenna.
Height doesn’t necessarily mean much for receiving on a specific band, such as the railroad in this case.
With that said, your setup is already leaps and bounds ahead of a standard stock rubber duck.

By the way, what antenna specifically do you have & what radio are you using?

Thanks. I have an SDS 100 with a SpectrumForce Antenna from scanner master

 

[trentbob]

So Am am looking at getting an antenna just for railroad listening. All the antennas I find for VHF are over 4 feet long 55 inches to be exact . Right now I have a 17 inch one an it receives ok. Should I get a longer one for better reception or stick with the smaller ones. This is for a mobile set up. Thanks.

My personal opinion is if you are just listening to Railroad frequencies, you're 17-in antenna is a quarter wave antenna and is what I prefer if I was going to just listen to Railroad.

The 55 in antennas you're referring to are 5/8 wave antennas. Since you're not transmitting and only receiving with your sds100 both are good choices but again I prefer the quarter wave 17 inch whip.

As far as the RG58 since it's a mobile application and not a long run you're okay with that as your signal loss is not significant..

As far as your mount being magnetic or a lip Mount or you.. drill a hole, I always prefer drilling a hole for the NM0 mount but that's not always an option.

I'm sure others will chime in with more detailed answers but me personally, I'd stay with the quarter wave 17-in whip.😉

 

[cbehr91]

I've never noticed a night-and-day difference using a 1/4 wave vs. a 5/8 wave for mobile monitoring. In testing with flipping between NOAA WX stations a weak station will come in around 1 S-unit stronger on a 5/8 wave vs. a 1/4 wave (again, not at all a night-and-day difference).

tl;dr keep using a 1/4 wave whip on your roof if you're happy with it.

 

[prcguy]

I've never noticed a night-and-day difference using a 1/4 wave vs. a 5/8 wave for mobile monitoring. In testing with flipping between NOAA WX stations a weak station will come in around 1 S-unit stronger on a 5/8 wave vs. a 1/4 wave (again, not at all a night-and-day difference).

tl;dr keep using a 1/4 wave whip on your roof if you're happy with it.

The difference is very noticeable when both antennas are compared within their resonant range. If you test a 5/8 tuned for 2m but test on VHF weather it will not work very well. If both antennas are tuned for 2m and you do a range test on 2m simplex you will then realize the benefits of a 5/8 over 1/4 wave.

 

[Ace9133uwu]

and you do a range test on 2m simplex

I’ll point out that we’re simply discussing receiving only. Not transmitting and receiving. That said, 1/4 wave is fine for RX on many bands, railroad included.
Source: owns & uses roughly a dozen 1/4 HT antennas for railroad & 2m RX.

 

[Ace9133uwu]

Thanks. I have an SDS 100 with a SpectrumForce Antenna from scanner master

I didn’t even receive a notification for your reply 🤦‍♂️
The SpectrumForce is pretty decent. I have one attached to a metal coffee can for my 996P2. The SDS100 is alright for VHF receiving, but I’ve never really had good luck with railroad monitoring on the 100.

 

[cbehr91]

The difference is very noticeable when both antennas are compared within their resonant range. If you test a 5/8 tuned for 2m but test on VHF weather it will not work very well. If both antennas are tuned for 2m and you do a range test on 2m simplex you will then realize the benefits of a 5/8 over 1/4 wave.

Both were (are) tuned to 160MHz. I also have a wideband 1/2 wave that I don't notice a difference between it and the 5/8.

 

[prcguy]

I’ll point out that we’re simply discussing receiving only. Not transmitting and receiving. That said, 1/4 wave is fine for RX on many bands, railroad included.
Source: owns & uses roughly a dozen 1/4 HT antennas for railroad & 2m RX.

Antennas like we are discussing are reciprocal, exact same effect on transmit and receive. A 5/8 compared to a 1/4 wave is a little better unless you’re snuggled up against the base of a mountain talking to a repeater on top.

 

[cbehr91]

I’ll point out that we’re simply discussing receiving only. Not transmitting and receiving. That said, 1/4 wave is fine for RX on many bands, railroad included.
Source: owns & uses roughly a dozen 1/4 HT antennas for railroad & 2m RX.

HT antennas are a different animal. Almost all of them are a serious compromise, including the ones you see on railroad radios. The best HT antenna I've ever used for railroad RX was an MFJ Long Ranger shortened by two sections from its maximum length, but who wants to walk around with a 3' long antenna?

 

[Ace9133uwu]

Almost all of them are a serious compromise

That’s true. I’ve tried multiple scanners and HT’s with multiple antenna solutions. Lots of trial and error. The new Wouxun KG-Q10H & Laird EXH160 are a perfect pair for me both at home and in the field. It’s nearly as good as my 996P2 on my Spectrum Force. Now a Boofwang UV5R using the same setup might underperform or just be barely average, whereas a Uniden 125 with a BNC to SMA adapter (how I set it up with a Laird) will be above average. But at this point, it’s all extreme specific cases based on location, geography of the land, weather, and usage. Long story short, almost any antenna is way better than a stock duck!