OPEK 4.5 dBi 1/2 Wave 26 MHz Bandwidth (148-174 MHz) VHF NGP Pre-tuned No Cutting Antenna
OPEK 4.5 dBi 1/2 Wave 26 MHz Bandwidth (148-174 MHz) VHF Antenna
Base Loaded – Wideband Pre-Tuned No Cutting VHF Antennas
Features:
• Wideband no tuning frequencies for seamless operation and ease of installation
• 4.5 dBi 1/2 Wave 26 MHz Bandwidth (148-174 MHz) VHF Antenna
• Rugged stainless steel tapered whip, heavy-duty spring for maximum durability and shock absorption
• Thick-wall housing, double seals with O ring and gasket for maximum weatherproofing and environment protection
• Compatible with all 1-1/8″ – 18 thread mounts including 3/4″ mounts
• Rugged stainless steel whip, heavy-duty spring for maximum durability and shock absorption
• Thick-wall housing, double seals with O ring and gasket for maximum weatherproofing and environment protection
• Compatible with all 1-1/8″ – 18 thread mounts including 3/4″ mounts
• OP-1229W will operate with a ground plane (GP & NGP)
• Overall Length 34.8 Inches
• Antenna Completely Assembled
We completed a comprehensive test report of the OPEK 1229W antenna vs the Comprod 576-75 antenna. Please see attached files. These reports were provided by the manufacturer (OPEK) with a strict testing guideline
The OPEK and Comprod are both VHF 1/2 wave, 148-174 MHz wide band, no ground plane (NGP) antennas. Both of these antennas are tuned with (NGP) which means it works best when mounted on a fender / mirror / window / clamp-on brackets with no or little ground plane. When a NGP antenna is used as a ground plane (GP) antenna, the original designed frequency might shift to an uncertain frequency. The performance and original characteristics such as the (VSWR & Return Loss) of the antenna also changes from the original antenna design.
OPEK designed their antennas to function according to its design purposes. Any other uses beyond its scope are not guaranteed. Although, most dealers are using the NGP antennas in a GP environment without any issues. A perfect example is to use a NGP antenna on a magnet which is mounted on top of the roof. If that is the case, it changes everything a NGP antenna is designed for and changes into a GP antenna. The original frequency 148-174 MHz could be shifted to 160-180 MHz as an example. The lines on the NGP and GP reports are moving differently. See attached files to view the difference.
We are very skeptical how well a NGP antenna works in a GP environment and how well it compares to its competitor. We have compiled a report based on three most popular mounting methods on a vehicle’s (fender, magnet & roof). Please keep in mind that the bigger minus (-) of the return loss the better the antenna is tuned. I will mark a star (*) for the winner of the lowest return loss. I hope you all enjoyed our findings.
Here is what we used for testing:
1) Agilent network spectrum analyzer model E5071C.
2) OPEK 1229W VHF 1/2 wave 148-174 MHz pre-tuned antenna with a rubber gasket.
3) Comprod 576-75 VHF 1/2 wave 148-174 MHz cut-tuned antenna with a rubber boot.
4) OPEK fender Bracket.
5) OPEK 3.5″ Magnet with 14′ RG58U coax. cable. Note: the OPEK antennas perform best when used with the OPEK 3.5″ magnet.
6) OPEK NMO cable assembly with 17′ RG58U coax. cable on a large ground plane to mimic the rooftop.
OPEK vs Comprod w/Fender Bracket Mounting (NGP Test):
| Markers | Freq. | OPEK 1229W Pre-Tuned | Comprod 576-75 Cut-Tuned | ||
|---|---|---|---|---|---|
| VSWR | Return Loss (dB) | VSWR | Return Loss (dB) | ||
| 1 | 148.00 MHz | 1.78 | -10.96* | 1.86 | -10.4 |
| 2 | 154.10 MHz | 1.59 | -12.75* | 1.68 | -11.85 |
| 3 | 158.94 MHz | 1.27 | -18.42* | 1.53 | -13.49 |
| 4 | 162.45 MHz | 1.21 | -20.26* | 1.54 | -13.44 |
| 5 | 168.12 MHz | 1.57 | -13.06 | 1.55 | -13.26* |
| 6 | 173.37 MHz | 1.65 | -12.17* | 1.71 | -11.59 |
OPEK vs Comprod w/3.5″ Magnet Mounting (GP Test):
| Markers | Freq. | OPEK 1229W Pre-Tuned | Comprod 576-75 Cut-Tuned | ||
|---|---|---|---|---|---|
| VSWR | Return Loss (dB) | VSWR | Return Loss (dB) | ||
| 1 | 148.00 MHz | 2.04 | -9.28 | 1.44 | -14.78* |
| 2 | 154.10 MHz | 1.56 | -13.11* | 1.7 | -11.68 |
| 3 | 158.94 MHz | 1.27 | -18.49* | 1.46 | -14.45 |
| 4 | 162.45 MHz | 1.25 | -18.91* | 1.35 | -16.4 |
| 5 | 168.12 MHz | 1.22 | -19.76* | 1.5 | -13.84 |
| 6 | 173.37 MHz | 1.62 | -12.49 | 1.55 | -13.24* |
OPEK vs Comprod w/Roof Mounting (GP Test):
| Markers | Freq. | OPEK 1229W Pre-Tuned | Comprod 576-75 Cut-Tuned | ||
|---|---|---|---|---|---|
| VSWR | Return Loss (dB) | VSWR | Return Loss (dB) | ||
| 1 | 148.00 MHz | 2.25 | -8.28 | 1.8 | -10.88* |
| 2 | 154.10 MHz | 1.72 | -11.5 | 1.6 | -12.72* |
| 3 | 158.94 MHz | 1.42 | -15.06* | 1.46 | -14.55 |
| 4 | 162.45 MHz | 1.36 | -16.27* | 1.52 | -13.63 |
| 5 | 168.12 MHz | 1.45 | -14.66* | 1.68 | -11.84 |
| 6 | 173.37 MHz | 1.75 | -11 | 2.21 | -8.46 |