Hi John,I have spent a lot of money trying to save money by buying Chinese crap. Incomprehensible "manuals", poor build and quality. I'm strictly an amateur antenna experimenter. I abhor using the Smith chart manually, and it's great to see the new hardware/software tech does all the hard work for you. However, I suspect that some individuals still prefer using their trusty slide rules. I had to use one, but I never loved it, and as soon as calculators became affordable, I immediately "lost" mine. But I digress...
RF Explorer Technology may sell something that works for you, John. Quoting from their website (j3.rf-explorer.com):
"RF Explorer Genuine Accessories are thoughtfully designed to be the perfect companions for achieving optimal RF performance at an affordable cost.
1. Near Field Antennas: Ideal for detecting radiation in devices, pre-EMC testing, locating hidden bugs, and pinpointing sources of radiation with precision.
2. General Purpose Antennas: Versatile SMA-compatible antennas that cover most frequencies of interest. Many are included with RF Explorer spectrum analyzer packages, ensuring convenience right out of the box.
3. RF Explorer Upconverter: Expands low-frequency support starting at 100 kHz for models like RF Explorer PRO, which begins at 15 MHz. A cost-effective and accurate solution to extend your device's frequency range.
4. Power Limiter: Essential for protecting RF Explorer Standard models from exposure to strong RF fields. Note: RF Explorer PRO and PLUS models include internal attenuators and do not require this accessory when enabled.
With RF Explorer Accessories, you can enhance your spectrum analysis capabilities while ensuring durability, versatility, and cost efficiency."
For HF and the Ham FSM module, after email chats with one of RF Explorer's engineers, I took an old shortwave radio antenna and "McGyvered" a BNC connector onto it. It extends to 5' and it performed very well on the HF Ham bands. I was shocked to see how intense the near field can be (at 10 m) using a 200 mW or 20 dBm WSPR signal with a multiband mobile antenna with loaded whips (a Comet UHV10). I can't imagine what the near field would be like at 100 watts! It certainly was an eye-opener, and I'm anxious to try out the 22 m addition once they release new firmware to include it. I can use the 20 m band to get some idea of the field strength and how close it is to the required value, and also see how accurate the equations used are to reality.
I had assumed that because I operate QRP and use digital modes (and pseudo digital Morse), I automatically complied with the Canadian EMCAB-2 regulations. Not so, it seems! Different antennas, using the same input power, have different intensities in their near fields. And different radiation patterns, of course. Using EZNEC is one thing, but seeing it with your own eyes via the RF Explorer with an antenna you brought into the real world is truly eye-opening and Wow! STL vs. dipoles vs. verticals. Ground-mounted vs. elevated. Etc., etc. WSPR is a great tool to combine with the RF Explorer, with its steady 2-minute transmission signal as you walk around the antenna under test.
I've never had as much fun designing and building antennas, even though I lack the academic qualifications to understand the theory 100%. But perhaps that's why it's more fun.
73,
Robert