Hi Udo,

Apologies for the slow delivery. International fully tracked delivery is very expensive as I do not sell enough to get a good trade discount. Using such services would significantly increase the price I would have to charge. Normally shipping arrives within the quoted 10 days, but on occasion there are unforseen delays which are normally associated with local postal services or customs clearances. All items are correctly marked to ensure the most expeditious clearance. I do think COVID19 has caused many delays worldwide recently, but I have been unable to get specific details from Royal Mail on a country by country basis.

Regarding performance, I am sorry that the antenna SWR does not meet your requirements for transmit. Such requirements are generally specific to the output amplifier of your system and I am not able to give a universal answer on its suitability for each and every system. For the majority of lower power systems the result is limited to a reduction in overall efficiency. Your spiral antenna has better than 50% efficiency at 300MHz. Again depending upon the specifics of your application this may or may not be considered good. For example a mobile phone maker would be pretty pleased with 50% efficiency within the size constraints of the device, a radar designer would not.

I do try to be as open and honest about the performance of my antennas as possible and try to provide as much reliable performance data as possible to enable those with specific requirements to make informed descisions. As you state, the antennas do meet the published specifications. However as these antennas did not meet your expectations, I would be happy to provide a refund? Just let me know in the comment below, or contact my Tindie store link.

Wish you all the best with your project.
HeexAndFlex