Many of you know Clyde VA7EIM, one of our most active club members. Clyde recently wanted to get a new multi-band antenna for his car. After some investigation on mobile antenna options, he selected the Comet CA-2x4SR in an NMO mount configuration.

This antenna is highly recommended by Kevin VE7XY (of OCARC), Brad VE7WBM, myself and many others for it's dual-band with gain capabilities and also it's extremely widebandedness. Wide bandwidth is important if you plan to listen to frequencies outside of the amateur bands.

Clyde installed the antenna on a middle-front-lip-of-trunk-NMO mount. This gives the antenna a really good ground plane. It's not quite as good as the centre of the roof, but reviewing the data below, it's hard to get any better.

The other day, Clyde and I met up to check out his install. With my RigExpert AA-230 Zoom antenna analyzer, we took at look at the SWR for VHF. Check out the results below.

The following plots show SWR on the vertical axis vs frequency on the horizontal axis. Any SWR below 2.0:1 is useable, but really, for VHF you want SWR below 1.5:1.

Here's a wide scan centred at 146.0 MHz, the centre of the HAM VHF band (blue highlighted section):

Yes, the lowest SWR is up at 150.5 MHz, but SWR is 1.1:1 or lower for the entire HAM VHF band - exceptional! We can see 1.09:1 at the cursor marker of 146.0 MHz.

Zooming in to look at the 1.5:1 marker frequencies:


We can see that the antenna performs well for any frequency between 139.5 MHz and 156.7 MHz, much wider than just the HAM VHF band.

Clyde can confidently work every frequency in the HAM VHF band with very high transmit efficiency/low SWR/great receive performance. But he can also now monitor nearby commercial and public service frequencies with good receive performance.

Unfortunately, the AA-230 Zoom does not cover the HAM UHF band, so we can't show you plots of the antenna's UHF performance. However, from my personal testing using an SWR bridge, I can attest to similar low SWR results across the entire HAM UHF band.

This is a great antenna for both regular use as well as situations where one might need cross-band repeat capabilities. Clyde's installation is very well done. Please approach him for a tour of his setup next time you see him.

FYI and 73,
NORAC Vice-President 2017-2019

Ps: Comet CA-2x4SR official description and specs from Comet's website:



Dual band, designed to assist Search & Rescue Volunteers and Professionals
1.5:1 or less SWR:
2:1 or less  SWR:
Gain: 3.8/6.2dBi (VHF/UHF)
Max Power: 150 watts
Length: 40 inches
Connector: NMO or PL-259 options, fold-over hinge included

The CA-2x4SR is a broad-band antenna designed for those needing voice communications on the ham radio, public service, land mobile, and FRS frequency ranges.

When the amateur radio community is working together with local search and rescue and other public service agencies, the CA-2x4SR antenna allows TX and RX capability in both bands! 

The coverage area and gain provided by the CA-2x4SR is remarkable. Whether used on VHF or UHF or both, it is an asset to the communications needs of amateurs and land mobile users simultaneously.