###### Abstract  
This paper presents a feasibility study for designing a floating patch antenna structure fed with a probe from a microstrip. The main premise is to eliminate the dielectric in the patch design, which is equivalent to having an air dielectric and leads to the necessity of proper support to fasten the patch in the air. The novelty of this paper is that this new device, apart from being fed with the though-wire technique directly from the microstrip line, has to be, by design, robust and easy to manufacture, and, at the same time, it has to present, simultaneously, good values in all of the performance indexes. A prototype has been designed, manufactured, and measured with good performance results: a bandwidth higher than 10% around 2.4 GHz, a radiation efficiency higher than 96%, a 9.63 dBi gain, and a wide beamwidth. The main advantages of this prototype, together with its good performance indexes, include its low fabrication cost, low losses, light weight, robustness, high integration capability, the complete removal of the dielectric material, and the use of a single post for feeding the patch while simultaneously fixing its floating position. floating patch; antenna; air substrate; microstrip; through-wire +
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In [8], the authors state that the optimal selection of the dielectric material and its thickness has little influence on the resonance frequency, but it is of paramount importance to achieve maximum radiation efficiency and bandwidth. The dielectric constant also affects the size of the patch: the higher the dielectric constant, the tinier the patch will be. This fact is used in [9], in which an antenna array at 2.45 GHz with a high relative permittivity substrate has been used to minimize the size of a human wearable device. Nevertheless, theoretically, the smaller the dielectric constant, the better the antenna performance will be [10]. In fact, in [11; 12; 13; 14], researchers proved theoretically and experimentally that a floating patch with an air dielectric improves the performance of the bandwidth and gain; however, this is at the cost of a small increase in size. This increment can be minimized by shorting posts and slots at the cost of increasing the manufacturing complexity [15]. Some examples of dielectric removal by using air as the separation between the floating patch and the feeding network have been reported in the literature; for instance, in [16], a suspended patch based on a microstrip coaxial probe feed technique was presented with an excellent radiation efficiency higher than 90%; however, this solution presents a poor fractional bandwidth of lower than 5%. On the other hand, in [17], a transparent water patch fed by an L-shaped probe was presented with a fractional bandwidth higher than 30% but a poor radiation efficiency of lower than 80% and higher manufacturing complexity. Another example, in [8], a floating patch fed by a microstrip and inserts was presented with a radiation efficiency of higher than 90% but a poor fractional bandwidth of less than 6%. As another example, in [18], a suspended conformal patch antenna was proposed, and the authors compared it to the non-conformal version, both of which include a non-floating patch and an air cavity backed between the patch substrate and the reflection ground. The best results give good values for the gain but a poor bandwidth, apart from the necessity of a supporting frame to make the air cavity. Furthermore, in [19; 20], examples of slot-strip-foam-inverted patch (RSSFIP) antennas and arrays are proposed, in which the single element antenna achieves an excellent gain value, but the device requires an H-shaped slot, two layers of substrate, and an additional metallic reflector layer, all of which are separated by two air layers that, in fact, increase the complexity of the manufacturing process.