Information collected and measured from my antennas.
Advertised details:
This antenna was replacing my Diamond X-50 2/70 antenna in 2025 The base of the antenna is at about 8.5m above street level, and just about the highest point of my house in JO21sj.
It appears that the VSWR in the 144-145 MHz band is well above 1:2.0 as can be seen in the picture above. This is confirmed measurinmg the VSWR with the FT991 + SX-600 SWR meter. (SWR=2.0) Odd detail: the FT991 SWR reads low and ok at about 1.1 - 1.2
The NanoVNA measures:
This afternoon there was substantial rainfall, so I wonder if there’s some kind of moisture ingress that affects the antenna?
The next day, the situation remains unchanged, although they antenna has fully dried up over night. Therefor the MA2000 is removed and replaced by a brand new Diamond X.50 (2025-SEPT-16).
My plan is to mount this antenna in the backyard on a temporary mount some time in the future to further investigate what is wrong with it.
Advertised details:
This antenna was installed on 16 september 2025, replacing the Lafayette MA2000. The base of this antenna is at about 8.5m above street level, and just about at the hightest point of my house in JO21sj.
A quick SWR check on 2m with my trusty-old MFJ259b shows that the VSWR is acceptable in the 2m band. As this antenna analyzer does not cover 70cm I also take a look with the nanoVNA.
This is what the nanovna H4 shows for the 2m band. The entire band is clearly showing an VSWR < 1.5 (yellow curve), which is as advertised. Marker 1 (at 143.0MHz) and Marker 3 (146.3MHz) are set on the VSWR 1.5 line. The minimum is found at 144.5MHz (VSWR 1.3).
The same measurement is done for the 70cm band.
Using the FT991 with a K-PO SX-600 VSWR meter in the coax feedline, show a VSWR of 1.3 on 145.450MHz using 5W of RF power.
And with the same setup we get a VSWR of 1.4 on 431.7MHz, which is a typical frequency for repeater relay input.
Using the 60dBm.com Ukrainian RF reflection bridge and my DSA815 Rigol Spectrum analyzer I was able to take this measurement for the 2m band:
Note that markers 2 and 3 are on the edges of the band (144.0 and 146.0MHz).
For the 70cm band we measure these values:
Based on information from PA3GER on the internet, a 2 meter “Slappe Arnold” was created using the following dimensions:
This antenna is hanging at the highest point of my attick, at about 8.5m about street level. It is mostly connected to a reprogrammed Kenwood TK780 for monitoring local traffic.
Measured with the MFJ-259b antenna analyzer, the VSWR in the middle off the 2m band is about 1.4
The results measured with the nanoVNA are very similar and show that the VSWR on the entire 2m band is at or below 1.5.
The measurement with the reflection bridge below shows that the entire 2m band has a reflection loss of no worse than 13dB. Which equals to a VSWR of 1.6 or better in the entire 2m band.
This antenna is used in-doors mostly for my trusty old T-813 for local FM contacts on 2m. As it’s hanging in-door against a wooden wall near other structures, the antenna dimensions had to be modified to make the antenna resonant in the 2m band. This detunes the 70cm usability, which is no issue (at least for now).
Measuring the PA0FBK antenna with the MFJ-259b antenna analyser shows a clear optimum in VSWR at 144.7MHz (VSWR 1.0).
On the nanoVNA it is easy to see the entire 2m band has VSWR < 1.5. So the in-door setup may not be ideal, it’s good enough for local traffic.
