ATM you can buy Donut Loop Broadband Antenna 10kHz-180MHz for $15.99 (in Banggood). Basically copy coupon, view price history or create e-mail price alert. You probably want to know what is the best price?
Latest coupon and price update (UTC):
Donut Loop Broadband Antenna Frequency Range 10kHz-180MHz with Low Impedance Converter
Banggood ($15.99)
Banggood warehouse is located in China. There are no active coupons for this product, but the price is pretty low isn’t it? Good or bad price? Well, this price is higher than average price ($15.29)
Link: Banggood product page
Price: $15.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Here is price history (for all/most countries) for Donut Loop Broadband Antenna 10kHz-180MHz.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).