Reception is improved when I touch another antenna to another. Why?

[MVUSA]

Using a Uniden BCT15X. Stock telescoping antenna installed. The length of the stock antenna is 25 inches extended.
I noticed that general reception in the 150 – 155 MHz range improved when I touched the end of the BCT15X stock antenna with a stock rubber ducky antenna from my old Uniden BR330T radio. The length of the BR330T rubber ducky is 5 3/4 inches.

I would describe the improved reception as follows:
The signal is a conventional 155MHz that is probably 800 feet above my location. Distance is unknown, I am not sure which repeater there are coming from.
With the stock antenna, I hear nothing. Maybe some faint static with no bars indicated. When I touch the rubber ducky to the end of the telescoping antenna, I can hear them and 2 bars are indicated.

I was wondering if I could get an explanation of what is happening, and how I would make a more permanent solution. I am guessing it’s not as simple as making a monopole antenna 30 3/4 in length?

Thanks in advance for the help

 

[LtDoc]

Basically what you are seeing is the 'duck' and your hand making the antenna longer. So, I would think that putting an external antenna on your scanner would be of benefit. As to what the extendable antenna and the 'duck' antenna, and your hand, amounts to (length), I wouldn't even guess. It would also help if the antenna were higher and outside, but, that isn't always possible.
- 'Doc

 

[rfradioconsult]

Simple answer, antennas are 90% magic and 10% physics. Your's fall into the 90% range

 

[MVUSA]

Basically what you are seeing is the 'duck' and your hand making the antenna longer. So, I would think that putting an external antenna on your scanner would be of benefit. As to what the extendable antenna and the 'duck' antenna, and your hand, amounts to (length), I wouldn't even guess. It would also help if the antenna were higher and outside, but, that isn't always possible.
- 'Doc

Right, forgot to mention the "hand" effect. I did roll a paper sleeve around the rubber ducky and slid it over the telescoping antenna.

I still receive the benefit.

As for outside, and higher... I am kinda stuck with what I have.
Technically, I have another 16 inches to the ceiling left over after doing the rubber ducky trick.

Am I technically approaching the correct antenna length for the 155MHz frequency?

 

[mancow]

You can check it yourself here.

Online Conversion - Frequency Wavelength Calculator

 

[MVUSA]

You can check it yourself here.

Online Conversion - Frequency Wavelength Calculator

Nice, thanks for the online calculator. This one does have all the different wave lengths as well.